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Visual and auditory signals are well-established components of avian courtship, but the role of chemical signaling remains poorly understood, particularly in mating systems with elaborate courtship displays. To test how chemical cues influence mating behavior we conducted two experiments in the lance-tailed manakin (Chiroxiphia lanceolata). First, in a field experiment, we tested the response of free-living males and females to manipulation of chemical cues at male display perches by cleaning the perches with ethanol or a dry cloth (control) and quantified a potential chemical signaling behavior (bill-wiping) in response to experimental manipulation. During bouts of dance perch maintenance and displays with a female present (i.e., activity relevant to female mate choice) males increased bill-wiping behavior during initial ethanol treatment periods. We also detected carryover effects of the ethanol treatment; in later treatment periods males bill-wiped more when the prior treatment was ethanol. The likelihood of a female either revisiting a display area or copulating with a male was unrelated to experimental treatment. Next, in captive trials, we assessed female preference for olfactory cues from males that differed in their genetic diversity, a trait previously identified as relevant to female mate choice. In contrast to similar trials in other bird species, females showed no clear preference. Together, these results provide some evidence for chemical signaling by males at display perches, but it remains unclear what information chemical cues convey. Significance statement: Chemical communication is an understudied phenomenon in birds, and especially so when it occurs as part of complex courtship displays. We investigated chemical signaling in the mating behavior of a highly polygynous bird with elaborate courtship displays by experimentally altering the chemical cues at courtship sites that are actively maintained by males. Male lance-tailed manakins detect and respond to changes in the chemical environment on display perches, however we detected no response from females. Our results contrast with other studies that detected significant responses to chemical cues by both males and females and suggest that association time with chemical cues may be important to their detection in avian systems. [ABSTRACT FROM AUTHOR]

We evaluated whether the availability of male mates affected mating strategies in a predominantly socially monogamous passerine, the grass wren Cistothorus platensis. We used the natural variation in adult sex ratio (ASR) and a male removal manipulation to assess if social polygyny was more frequent when male mates were less abundant. We evaluated the potential costs that females paid when breeding with a polygynous male by assessing how males distributed parental care between nests and analysing four correlates of breeding success (clutch size, nestling body condition, number of fledglings, and nest fate). Social monogamy was predominant when males were abundant while social polygyny was more frequent when the ASR was female-biased. The removal of males was associated with a high rate of social polygyny. Social polygyny occurred when males annexed the territory of a neighbouring female or when an unpaired female settled within the territory of a mated male. We identified several potential costs of social polygyny to females. Secondary females (females that laid eggs after the primary female) produced nestlings of lower body condition during the first half of the breeding season, received less help in feeding the brood, and increased their parental contribution. We suggest that while intrasexual competition may constrain social polygyny when males are abundant, reduced female life expectancy combined with moderate costs of male desertion may facilitate social polygyny when potential male mates are not available. Significance statement: Social mating systems are thought to reflect the outcomes of optimal decisions made by females and males confronted with variation in the quality of territories and/or mates. However, demographic factors and life-history traits may constrain individual decisions. We studied how the availability of male mates might predispose grass wrens to social monogamy and constrain social polygyny. We found that social monogamy was predominant when males were more frequent while social polygyny increased when males were less abundant (female-biased adult sex ratio). Moreover, the removal of males in a plot early in the breeding season biased the adult sex ratio towards females and produced a polygyny rate comparable to rates in years when males were less abundant in other plots. Our results suggest that the abundance of male mates can affect individual mating decisions, by reducing male-male competition and/or the mating option for females. [ABSTRACT FROM AUTHOR]

Polygamy is a form of "one-sided" consensually non-monogamous relationship where one person has multiple committed partners, each of whom is only involved with that one person. It was likely a reoccurring feature of ancestral mating that posed adaptive problems for our ancestors. Yet polygamy, and multi-partnering more generally, is understudied in Western cultures, raising questions about the existence of polygamous interest and whether this is calibrated adaptively to personal conditions. In two studies, we examined polygamous interest in two heterosexual online samples from the UK. In Study 1 (N = 393), modest interest was found for polygamous relationships overall. Men were six times more open to polygyny than women, but there was little sex difference in openness to polyandry. Further analysis revealed that all forms of multi-partnering were undesirable relative to singlehood and monogamy; however, consensual multi-partner relationships were less undesirable than non-consensual ones. Sex differences were largest for polygyny and arrangements where men had agreed access to a casual partner alongside a committed one, yet these were two of the most acceptable forms of multi-partnering when men and women's responses were combined. Sociosexuality positively predicted interest in most forms of multi-partnering. Study 2 (N = 735) focused on polygyny and added status-linked traits as predictors. The results of Study 1 were broadly replicated, though the status-linked traits did not predict polygynous interest specifically. Instead, sociosexuality and male intrasexual competitiveness uniquely predicted general interest in multi-partner relationships. Overall, interest in polygamy appears to emerge despite social discouragement and sex differences in interest track the relative costs and benefits associated with it. However, there is no strong evidence that polygamous interest is uniquely calibrated to personal conditions when compared to other forms of multi-partnering. [ABSTRACT FROM AUTHOR]

Although random meiosis should prevent the facultative adjustment of offspring sex ratio, theory predicts that females should produce more of the sex with the higher reproductive value. We reported a case of offspring sex ratio manipulation in grass wrens Cistothorus platensis. Males in better body condition would have higher reproductive value than females due to the potential for social polygyny and extra-pair fertilizations. On the other hand, local demography influences reproductive strategies in grass wrens as male abundance affects both social polygyny and extra-pair paternity frequencies. We evaluated whether females bias their brood sex ratio in response to adult sex ratio and nestling body condition (a proxy for female's prospects of producing high-quality males). Females raised more male offspring when males were less abundant in the population (female-biased adult sex ratio). However, we found no relationship between nestling body condition and brood sex ratio, suggesting that females did not bias the brood sex ratio towards males when able to raise nestlings in better body condition. Taken together, our results provide the first suggestive evidence that female birds can manipulate their offspring sex ratio in response to the adult sex ratio. [ABSTRACT FROM AUTHOR]

Mismatches between current and potential species distributions are commonplace due to lags in the response of populations to changing environmental conditions. The prevailing mating system may contribute to such lags where it leads to mating failure at the range edge, but how active dispersers might mitigate these lags using social information to inform dispersal strategies warrants greater exploration. We used an individual-based model to explore how different mating systems for species that actively search for habitat can impose a filter on the ability to colonise empty, fragmented landscapes, and explored how using social information during dispersal can mitigate the lags caused by more constrained mating systems. The mate-finding requirements implemented in two-sex models consistently led to slower range expansion compared to those that were not mate limited (i.e., female only models), even when mating was polygynous. A mate-search settlement strategy reduced the proportion of unmated females at the range edge but had little impact on rate of spread. In contrast, a negative density-dependent settlement strategy resulted in much faster spread, which could be explained by a greater number of long-distance dispersal events. Our findings suggest that even low rates of mating failure at the range edge can lead to considerable lags in range expansion, though dispersal strategies that favour colonising more distant, sparsely occupied habitat patches may effectively mitigate these lags. [ABSTRACT FROM AUTHOR]

Double brooding, the laying of a second clutch after successfully fledging young from a first nest in a season, is a common reproductive strategy among short-lived birds to increase annual breeding success. Nevertheless, there is widespread intra- and interspecific variation in the probability of producing a second clutch. Given that the frequency of double brooding could affect population growth rate, knowing what factors contribute to this phenomenon is also important in the conservation management of threatened facultative double-brooded species. Here, we examine the frequency of double brooding and the factors affecting the probability of this reproductive strategy in a population of the Great Reed Warbler, Acrocephalus arundinaceus, in south-western Slovakia. Results of a 15-year study (2008–2022) revealed low overall rate of double brooding in the Great Reed Warbler (5.6% per year, 0–15.4%). The length of breeding season, timing of the first clutch laying date and the size of the first broods were key factors influencing the female's decision to initiate a second clutch. On the other hand, successful brood parasitism did not affect second clutch initiation, which contrasts with our prediction. Given that only monogamous or primary females initiated a second clutch after successfully rearing a first one, we assume that producing two broods within the same season may be an alternative strategy for monogamous males to increase their annual reproductive output in this facultatively polygynous species. Therefore, due to relatively high rate of polygyny, we probably cannot expect higher rate of double broodings in the Great Reed Warbler in the future either. [ABSTRACT FROM AUTHOR]

Successful reproduction of two subspecies of Harting's vole in monogamous pairs (monogamous groups, 35 pairs for each) was shown. The results obtained in modeling the experimental polygyny revealed a different attitude of females of the two subspecies to the formation of communal groups. In polygynous groups of M. h. lydius, regardless of the relationship of the females (35 groups consisting of sisters and 20 groups of unrelated females), the intensity of reproduction and the proportion of successfully reared pups decreased significantly compared to the monogamous groups. With high energy costs for reproduction, there were significantly fewer reared pups per mother giving birth than in the monogamous groups, thus suggesting the predominance of monogamy in this subspecies. On the contrary, related females of M. h. hartingi bred successfully in communal groups (35 groups of sisters), demonstrating a high tolerance, a tendency to co-rearing and feeding the pups, and low infant mortality. In polygynous groups consisting of unrelated females (20 groups), reproductive success decreased due to increased infant mortality. Possible benefits of communal reproduction in this subspecies are discussed, as well as the likely relationship with habitat fragmentation under such conditions and with a lack of vacancies for the dispersal of young animals, which may be an important adaptation for this subspecies of voles. [ABSTRACT FROM AUTHOR]

Vocalizations differ substantially between the sexes in many primates, and low-frequency male vocalizations may be favored by sexual selection because they intimidate rivals and/or attract mates. Sexual dimorphism in fundamental frequency may be more pronounced in species with more intense male mating competition and in those with large group size, where social knowledge is limited and efficient judgment of potential mates and competitors is crucial. These non-mutually exclusive explanations have not been tested simultaneously across primate species. In a sample of vocalizations (n = 1914 recordings) across 37 anthropoid species, we investigated whether fundamental frequency dimorphism evolved in association with increased intensity of mating competition (H1), large group size (H2), multilevel social organization (H3), a trade-off against the intensity of sperm competition (H4), and/or poor acoustic habitats (H5), controlling for phylogeny and body size dimorphism. We show that fundamental frequency dimorphism increased in evolutionary transitions towards larger group size and polygyny. Findings suggest that low-frequency male vocalizations in primates may have been driven by selection to win mating opportunities by avoiding costly fights and may be more important in larger groups, where limited social knowledge affords advantages to rapid assessment of status and threat potential via conspicuous secondary sexual characteristics. Sexual dimorphism in the fundamental frequency of primate vocalizations is variable. Here, the authors examine 1914 vocalizations from 37 anthropoid species to find that fundamental frequency dimorphism increased with larger group size and polygyny, due to sexual selection. [ABSTRACT FROM AUTHOR]

Group genetic diversity is usually associated with a reduced risk of disease outbreak and a slower rate of pathogen transmission. In social insects, multiple mating by queens (polyandry) evolved several times albeit reducing worker's inclusive fitness. One major hypothesis suggests that polyandry has been selected for to mitigate the risk of outbreak thanks to increased genetic diversity within colonies. We investigated this hypothesis in the ant Cataglyphis mauritanica, in which nestmate workers are produced by several clonal, single-mated queens. Using natural colonies, we correlated genetic diversity with worker survival to a fungal entomopathogen. We further tested whether workers from different paternal lineages (but a common maternal genome) show differential resistance in experimentally single- or multiple-patriline groups, and whether an increased number of patrilines in a group improved disease resistance. We show that workers from distinct patrilines vary in their resistance to a pathogen in single-patriline colonies, but the difference among patrilines disappears when they are mixed in multiple-patriline colonies. Furthermore, pathogen resistance was affected by the number of patrilines in a group, with two- and three-patriline groups being more resistant than single-patriline groups. However, resistance did not differ between groups made of two and three patrilines; similarly, it was not associated with genetic diversity in natural colonies. Overall, our results suggest that collective disease defenses might homogenize workers' resistance from different patrilines and, thereby, stabilize colony resistance. Significance Statement: The occurrence of multiple breeders in insect societies has been hypothesized to be selected for because increased within-colony genetic diversity reduces the risk of severe outbreaks. We show that nestmate workers from distinct paternal lineages vary in their resistance to pathogens when reared in single-patriline groups. However, this difference disappears when workers are mixed in multiple-patriline groups. These results suggest that multiple mating by queens dilutes the deleterious consequences of a single patriline producing only susceptible offspring, rather than directly enhancing pathogen resistance. [ABSTRACT FROM AUTHOR]

Cooperation between kin and cooperation between non-kin often appear functionally similar, but the evolutionary mechanisms that drive the emergence of these two forms of cooperation can be dramatically different. The mechanisms responsible for non-kin cooperation, in particular, are not well established in an empirical context. To truly understand the emergence of non-kin cooperation, the fitness outcomes of cooperation should be compared with the alternate strategy of solitary living in the same environment. Ant populations that contain a mix of queens who found nests alone (monogyny), and cooperative unrelated ant queens who found nests together and remain together through colony development (primary polygyny), provide a useful natural context to make such a comparison. To estimate the reproductive costs for primary polygyny relative to solitary nest founding, we measured alate (reproductive) production for colonies in a mixed population of polygynous and monogynous California harvester ant colonies over a 2-year period. Colony-level reproductive output was not substantially higher in polygynous colonies compared to those with single queens, and consequent per-queen reproductive gain was significantly lower. Given that polygynous queens in this population are unrelated, nest sharing thus generates a significant annual and potentially lifetime cost for cooperative queens. Comparative measures of colony dynamics, however, suggest that polygynous colonies have a larger or more active workforce than monogynous colonies. Additionally, polygynous colonies may be more conservative than monogynous colonies in resource allocation towards reproduction. These results collectively suggest that primary polygyny generates annual reproductive fitness costs. However, polygynous colonies likely also shift life history strategies in ways that emphasize long-term survival and colony growth over immediate reproduction. Over time, this shift may mitigate the annual fitness costs of cooperation. Significance statement: When things get difficult, it pays to work together. In some ant species, unrelated queens form long-term cooperative associations that share resources and a workforce within a single nest. The fitness consequences and evolutionary drivers of non-kin cooperation in this and other systems are unclear. We compared the reproductive investment and colony dynamics of single-queen and multi-queen California harvester ant colonies in a shared environment to directly compare the fitness of cooperative and non-cooperative queens. Our data suggest that cooperation not only lowers annual per-queen reproduction, but also produces a more robust colony that may recoup annual fitness losses by extending colony longevity. [ABSTRACT FROM AUTHOR]

The formation of expansive multi-nest and multi-queen supercolonies is perhaps the most important factor responsible for the ecological success of invasive ants. The odorous house ant, Tapinoma sessile, is a widespread ant native to North America. T. sessile is a challenging urban pest, but also serves as an interesting system to study ant social organization and invasion biology. This is due to its remarkable dichotomy in colony social and spatial structure between natural and urban environments. Natural colonies typically consist of a small number of workers, inhabit a single nest, and are monogyne whereas urban colonies show extreme polygyny and polydomy and form large supercolonies. The current study examined the extent to which T. sessile colonies from different habitats (natural vs. urban) and social structures (monogynous vs. polygynous) exhibit aggression toward alien conspecifics. Additionally, interactions between mutually aggressive colonies were examined in colony fusion experiments to assess the potential role of colony fusion as a mechanism leading to supercolony formation. Aggression assays demonstrated high levels of aggression in pairings involving workers from different urban colonies and workers from different natural colonies, but low aggression in pairings involving queens from different urban colonies. Colony merging tests demonstrated that urban T. sessile colonies are highly aggressive to each other, but capable of fusing under laboratory conditions when competing for limited nesting and food resources. Despite highly aggressive interactions and relatively high worker and queen mortality, all colony pairs merged in 3–5 days. Fusion occurred after most workers died and the survivors merged. This result suggests that the success of T. sessile in urban areas may be driven, at least in part, by successful colony mergers of unrelated colonies which may be determined by ecological constraints such as seasonal shortages in nest and/or food availability. In summary, two independent factors including the growth of a single colony and/or the merger of multiple colonies may be responsible for the evolution of supercolonies in invasive ants. Both processes may be happening simultaneously and may act synergistically to produce supercolonies. [ABSTRACT FROM AUTHOR]

As small-bodied terrestrial organisms, insects face severe desiccation risks in arid environments, and these risks are increasing under climate change. Here, we investigate the physiological, chemical, and behavioral mechanisms by which harvester ants, one of the most abundant arid-adapted insect groups, cope with desiccating environmental conditions. We aimed to understand how body size, cuticular hydrocarbon profiles, and queen number impact worker desiccation resistance in the facultatively polygynous harvester ant, Pogonomyrmex californicus. We measured survival at 0% humidity of field-collected worker ants sourced from three closely situated populations within a semi-arid region of southern California. These populations vary in queen number, with one population dominated by multi-queen colonies (primary polygyny), one population dominated by single-queen colonies, and one containing an even mix of single- and multi-queen colonies. We found no effect of population on worker survival in desiccation assays, suggesting that queen number does not influence colony desiccation resistance. Across populations, however, body mass and cuticular hydrocarbon profiles significantly predicted desiccation resistance. Larger-bodied workers survived longer in desiccation assays, emphasizing the importance of reduced surface area-to-volume ratios in maintaining water balance. Additionally, we observed a positive relationship between desiccation resistance and the abundance of n-alkanes, supporting previous work that has linked these high-melting point compounds to improved body water conservation. Together, these results contribute to an emerging model explaining the physiological mechanisms of desiccation resistance in insects. [ABSTRACT FROM AUTHOR]

Variation in mating systems and in individuals' copulation patterns can have important consequences for the genetic structure of a population and ultimately its evolution. Whilst most gorilla sub-species form single-male, polygynous reproductive groups, mountain gorillas have both single-male and multimale reproductive groups. Considerable research has investigated the mating patterns of males in these multimale groups, but comparatively little is known about females. We investigated the copulation patterns of 71 female mountain gorillas over 13 years. We found that most sexually active, fecundable females in multimale groups had multiple mating partners. Females' copulation patterns varied based on their reproductive stage, mating most often and with the greatest number of partners when they were pregnant, and least often when they had young dependent offspring. Females copulated throughout pregnancy, with pregnant females copulating more frequently in single-male groups than in multimale groups. Mating also varied with age, with older females mating less often and with fewer partners. Our findings confirm that when females transfer between single-male and multimale groups, they predominantly switch from copulating with one male to copulating with multiple males, and that females are also flexibly adjusting their copulation patterns across their lifetimes. This highlights the considerable variability of the mountain gorillas mating system, particularly from the female perspective, and the importance of accounting for within-species variation in copulation patterns. Significance statement: Patterns of mating can vary both between individuals of the same species and within individuals across their lives. These patterns influence the genetic structure of a population. By examining copulation patterns in female mountain gorillas, we demonstrate that whilst females in single-male groups have only one mating partner, females in multi-male groups predominantly have multiple partners across a year. They also alter their copulation patterns across their lifetimes, copulating less often and with fewer partners as they age, and copulating most when pregnant. Our results highlight the flexibility with which female mountain gorillas can adjust their copulation patterns across their lifetimes, as the costs and benefits of copulation shift. [ABSTRACT FROM AUTHOR]

The structure of Ghanaian families has significantly changed over the years. Even so, some features of the traditional Ghanaian family have remained. For instance, polygynous families continue to be common. This study examined relationships between family structure and intimate partner violence among women in Ghana. Specifically, we investigated differences in the IPV experiences of women in polygynous families compared to those in monogamous families, and we explored the mechanisms linking polygyny with IPV. We used data on 2,289 ever-married Ghanaian women aged 18 years and above and applied random-effects logit models to determine differences in the IPV risks for women in the two family structures. A higher proportion of women in polygynous families were unemployed than their comparators in monogamous families, and they had lower levels of education. They had limited autonomy and strong patriarchal values and were significantly more likely to experience physical, sexual, and emotional/psychological violence. Their IPV risk was exacerbated by their lack of socio-economic empowerment, limited autonomy, and strong belief in patriarchal norms. Net of these factors, polygynous women were still disadvantaged, pointing to existing unobserved differences between the two family structures or differences in family dynamics, with implications for IPV. We propose that policy makers provide educational and employment opportunities for women in general, while targeting polygynous women with specific interventions to improve their self-efficacy and autonomy. [ABSTRACT FROM AUTHOR]

Stoplight parrotfish, Sparisoma viride, are hermaphroditic fish that exhibit a complex social structure in which terminal phase (TP) males control a territory of initial phase (IP) individuals (mostly female, rarely male) called a harem. These fish are prolific herbivores that maintain the health of coral reefs by consuming or removing algae that competes with coral for space. In this study, we estimate the influence of food availability, structural complexity, and conspecific density on territory size in S. viride TP males on reef sites in the middle Florida Keys. Divers estimated the territory sizes of both TP and IP individuals by following fish and dropping markers. Divers also estimated the substrate composition, conspecific density, and physical complexity around these territories. TP territories were roughly circular and only overlapped with IP individuals on the outer edges of the TP territory, resulting in TP territories being significantly larger. While TP territory size was positively influenced by the body size of the TP male and negatively influenced by the number of IP individuals, the average ratio of IP:TP individuals was 2.99:1 (± 0.31 SE, range 1–12) for each TP territory regardless of body size. These results suggest that TP males adjust their territory sizes to maintain an apparent optima for the number of females within harems and that the density of conspecifics can potentially influence the timing of sexual transitions in these fish. These results also suggest that S. viride have a polygynous mating structure that is driven by female defense rather than resource defense. [ABSTRACT FROM AUTHOR]

Understanding the main factors driving the evolution of mating systems is a major goal of behavioral ecology. In ungulates, the transition from forests to open habitats and the accompanying clustered spatial distribution of females are thought to have promoted an evolutionary shift from monogamy to polygyny. However, no field-based studies to date have tested in the field whether such changes in ecological conditions promote a shift from monogamy to polygyny. We investigated mating systems of the Japanese serow, which is an evolutionarily ancestral and solitary species among caprids, living in the area with subalpine forest and alpine meadows over 7 years. We evaluated the effects of habitat characteristics on mating systems using within population comparisons. In this site, females form solitary territories in subalpine forests but group territories in alpine meadows. Males defended most of their home ranges as territories, and both social monogamy (29.6%; one male with one female) and polygyny (70.4%; one male with 2–5 females) were observed. Males in alpine meadows formed mating units with more females, whereas males in subalpine forests formed mating units with single females. We show that open habitats promote the transition from social monogamy to polygyny and a higher degree of social polygyny. Our findings suggest that the main factor affecting the mating system is the spatial dispersion of females (solitary territory or group territory), which depends on habitat structure (closed or open). Significance statement: The Japanese serow is an ungulate that mainly inhabits forests and is assumed to possess the ancestral social systems for caprids, such as solitary and monogamous with territory. We found that open habitats, such as alpine meadows, promote the transition from monogamous to polygynous territory in the Japanese serow. In the study site, alpine meadows promote the transition from solitary territory to group territory of females. Thus, our results suggest that the main factor affecting the mating system is the spatial dispersion of females (solitary or group territory), which depends on habitat structure (subalpine forests or alpine meadows). Our findings provide evidence for a social evolutionary pattern in caprids, whereby the spread of forest-dwelling ancestors into open mountains promote evolution from social monogamy to polygyny. [ABSTRACT FROM AUTHOR]

Males in scramble competitive species that are in better condition are expected to have better endurance and thus be able to travel farther during bouts of mate searching. In this study, we use radio telemetry to field test the hypothesis that male Cook Strait giant weta Deinacrida rugosa (Orthoptera: Anostostomatidae) in better body condition accrue more mates because they are more mobile (i.e., travel farther per night in mate searches). Our study showed that males travel significantly farther, on average, each night than females and that individuals exhibit consistent travel distances and body conditions across days. As predicted, we found that male mating success was influenced by body condition and travel distance; however, contrary to expectation, both variables were negatively related to mating success. Contrary to expectation, we did not find an effect of body condition on travel distance in either sex nor did we find that increased nightly travel was more costly to body condition. We suggest that males in our study population that are lighter for their body weight (i.e., poorer condition) might be superior in sprints for nearby females. Consequently, these successful males will then reduce their movement because females are relatively sedentary. If a male is unable to acquire a female that is nearby, he is likely then obligated to engage in a prolonged mate search that is generally unsuccessful. Significance statement: Males in better body condition are expected to be more successful in scrambles for mates because they should have better endurance and thus be able to travel farther while mate searching. Our field test found, as predicted, that the mating success of male Cook Strait giant weta Deinacrida rugosa (Orthoptera: Anostostomatidae) was influenced by body condition and travel distance; however, contrary to expectation, both variables were negatively related to mating success. Contrary to expectation, we found that nightly mate searching had no effect on body condition and vice versa. Our study presents rare evidence of male mating success in a scramble competitive species being affected by body condition and mate-searching effort (as measured by travel distance) albeit in a manner opposite to prediction. [ABSTRACT FROM AUTHOR]

The wild boar (Sus scrofa), a polygynous species, rapidly expanded its geographical range and increased its population size in South Korea following the extinction of large carnivores and changes to rural environments. Understanding wild boar reproductive traits and strategies is essential for their effective management; however, studies in this area are lacking. Using samples collected from hunting bags, the relationships between 1) litter size and female weight and 2) fetal sex ratio and female body condition were examined to understand wild boar life-history strategies. Wild boars showed a seasonal breeding pattern that maximized reproduction. Litter size (mean = 5.7 ± 1.7) was correlated with female weight, whereas fetal sex ratio was not explained by female body condition. However, the heaviest ranked fetuses within the litters were male-biased. Wild boars aged three years or less accounted for 90% of the total population, and sexual dimorphism developed from two years of age. Considering that their reproductive strategy is more effective (i.e., early gestation and large litter size) than that of other polygynous species, the Trivers–Willard model was not supported for the wild boars in this study. Instead, females adjusted the sex of the heaviest fetus in the litter to maximize lifetime reproductive success. [ABSTRACT FROM AUTHOR]

It is long established that queens of social insects, including termites, maintain their reproductive dominance with queen primer pheromones (QPPs). Yet, the QPP chemistry has only been elucidated in a single species of lower termites. By contrast, the most diversified termite family Termitidae (higher termites), comprising over 70% of termite species, has so far resisted all attempts at QPP identification. Here, we show that the queen- and egg-specific sesquiterpene (3R,6E)-nerolidol acts as the QPP in the higher termite Embiratermes neotenicus. This species has a polygynous breeding system, in which the primary queen is replaced by multiple neotenic queens of parthenogenetic origin. We demonstrate that (3R,6E)-nerolidol suppresses the development of these parthenogenetic queens and thus mimics the presence of mature queen(s). It acts as an airborne signal and may be used to optimize the number of queens, thus being the key regulatory element in the special breeding system of E. neotenicus. A queen primer pheromone in higher termites is identified and shown to control the development of new queens in the colony, and acts as an airborne signal detected via olfaction. [ABSTRACT FROM AUTHOR]

Reproduction involves high energetic costs which are related to behaviour and gamete production. In females energy allocation to gamete production has been well documented. However, estimations of male investment in seminal material are scarce. The present study aims to assess and compare male investment in four brachyuran species by determining biochemical substrates present in the vasa deferentia to subsequently estimate energetic investment during the reproductive cycle. We identified two groups with contrasting energy investments. Two species, Homalaspis plana and Romaleon setosum, showed high investment due to significant quantities of proteins and lipids. Both species are characterised by large and complex vasa deferentia, and the formation of a remarkably large sperm plug deposited to the female after copulation as a sperm competition avoidance strategy. In contrast, Metacarcinus edwardsii and Taliepus dentatus invested little energy in their smaller-sized and simpler vasa deferentia. Morpho-functional traits may play a key role in determining the investment, which may also be influenced by mechanisms (i.e. mating tactics) to prevent sperm competition and the intensity of polygyny. This study emphasises the high amount of energy males invest in seminal material and highlights the diversity of mating strategies in Brachyura, which are reflected even on the physiological level. [ABSTRACT FROM AUTHOR]

Social polygyny usually benefits males by increasing the number of offspring, whereas it is detrimental for females as they must share the resources provided by their mate. An intersexual conflict may exist in animals with obligatory bi-parental care, such as birds of prey, in which females incubate and brood, whereas males provision food for their families. Long-term ringing data from Eurasian kestrels (Falco tinnunculus) breeding in nest-boxes and data on density indices of main prey animals (voles) were collected during 1985–2013 in western Finland to study polygynous behaviour. Of 1294 males, 54 (4.2%) were encountered at two (53) or three (1) nests during the same breeding season. Polygyny occurred more frequently during years of high vole abundance. The distances between nests of corresponding primary and secondary females were greater (median 1010 m) than the distances from nests of primary females to the nearest vacant nest-box (median 455 m). Twenty-eight (53%) of 53 secondary females had nearest available monogamous male within 2 km from their nest-boxes, indicating that mating options were available. Secondary females produced 30% less fledged offspring than simultaneously laying monogamously paired females. The abundance of prey animals is apparently alleviating the effort of males mating with multiple females. Spacing out the nests of primary and secondary females implies deceptive behaviour in the nest-site selection of polygynous males. Contradicting the polygyny threshold model, reproductive success of secondary females was significantly reduced in comparison to monogamous females laying simultaneously. These results show that secondary kestrel females apparently made a maladaptive choice, likely because they were deceived to accept polygynous mating status during the courtship feeding period. Significance statement: As dedicated parental effort of both the male and the female is vital to ensure the offspring survival amongst animals with obligatory bi-parental care, polygyny should be inherently a maladaptive mating strategy for females. However, regular social polygyny has been documented in at least 10% of bird species from ten orders. Previous studies on breeding success of polygynous birds of prey indicate reduced offspring production of secondary female partners with no apparent cause for females to choose polygynous males over other mating options. We showed that polygyny in Eurasian kestrels is frequent when food is abundant facilitating males to provision their two or more females during courtship feeding. Polygynous males space out their two nests thus attempting to hide their mating status from their secondary partners which suffer from their mate choice in form of poor reproductive success. Therefore, amongst the "cost of polygyny to females" hypotheses, the deceptive behaviour of males during courtship feeding appeared to be an apparent explanation for maladaptive mate choice of secondary females. [ABSTRACT FROM AUTHOR]

Sleep and sleep-related behaviors are integral components of primate behavior and ecology that are linked to various habitat-specific factors and often are modified in response to environmental fluctuations and threats. Despite the growing literature on primates, information on sleep-related behaviors of tarsiers remains sparse, especially for Philippine tarsiers, where our current understanding is hampered by the paucity of studies on wild populations. We radio-tracked eight Philippine tarsiers inhabiting a protected forest fragment between December 2016 and February 2018 to assess their sleeping site selection, sleep-related positional behavior, and social system. From 266 instantaneous sampling bouts, where each tarsier was observed a maximum of once per day, we found that the tarsiers frequently used trees with thickets of lianas and at least 15 plant species as sleeping sites. They slept from ground level to above 8 m, with most sightings at 3 to 6 m, and recurrent detections above 8 m, and preferred a flexed resting posture, on angled or horizontal, small-sized lianas or branches. Although frequently solitary, they also slept in pairs and in small groups of up to four individuals. We inferred polygyny based on observations of one adult male who associated and huddled with two nonassociated adult females, and direct male care through huddling and accompaniment. Our study revealed increased height use and gregariousness not previously described for Philippine tarsiers, shedding light on potential flexible behaviors by nocturnal primates in fragmented landscapes. Sleep-related behaviors present another avenue of research that has important implications on their conservation. [ABSTRACT FROM AUTHOR]

Weight- (WAZ), height- (HAZ), and BMI-for-age (BMIZ) are frequently used to assess malnutrition among children. These measures represent different categories of risk and are usually hypothesized to be affected by distinct factors, despite their inherent relatedness. Life history theory suggests weight should be sacrificed before height, indicating a demonstrable relationship among them. Here we evaluate impact of family composition and household economics on these measures of nutritional status and explore the role of WAZ as a factor in HAZ. Anthropometrics, family demographics, and measures of household economy were collected from Sidama agropastoralist children in a peri-urban village in southwestern Ethiopia (n = 157; 79 girls). Just over half of the sample (50.9%) had z-scores of − 2SD or below on at least one measure, indicating an elevated risk of morbidity/mortality; 30% were at or below − 2SD on two or more measures. We used hierarchical linear regression with random intercept analysis to model WAZ and HAZ. Siblings and crop sales significantly decrease WAZ while electricity, agriculture, and polygyny improve z-scores; however, an interaction between polygyny and siblings indicates negative effects of siblings in polygynous families and positive effects in nonpolygynous ones (adj. R2 = 66.5%). For HAZ, agriculture and electricity are positively associated with z-scores whereas siblings have a negative effect; the interaction term again indicates that effects of siblings vary in polygynous and nonpolygynous families (adj. R2 = 74.2%). A mediation model exploring the role of weight in height outcomes suggests not only that WAZ has direct effects on HAZ but also that effects of electricity and agriculture on HAZ are partially mediated by WAZ. Our findings indicate that WAZ and HAZ are primarily affected by shared variables, but effects of siblings vary by polygyny status. Long-term outcomes (HAZ) among Sidama children would likely benefit from interventions focused on stabilizing WAZ across family members. [ABSTRACT FROM AUTHOR]

Ecological studies of boxfishes (Ostraciidae) are relatively limited, especially those related to mating systems. A few boxfishes have been shown to maintain harem polygyny, where males mate with cohabiting females within their territories; however, no other type of mating system has been reported for ostraciids. We conducted a field observational survey of Ostracion meleagris on the reefs of Kuchierabu-jima Island, Japan, focusing on home range distribution patterns and mating relationships among individuals. The spotted boxfish O. meleagris established a feeding home range on shallow reefs and migrated several hundred meters offshore most evenings, where pair spawning with high ascending behaviors (median: 7.2 m) from considerable depths (median: 8.5 m) occurred. Males began daily offshore migration earlier than females and waited for the approaches of females within their mating territories. Some territorial males maintained multiple mating opportunities each evening. Thus, the mating system of this boxfish is considered a male territory-visiting polygamy. The optimum GLMM model for explaining male mating success included the water depth of the male territory as a parameter, suggesting its importance as a factor in the mate choice of the boxfish. Their armored bodies make them less vulnerable to predation, which allows the boxfish to migrate a long way daily to spawn, using both shallow reefs suitable for foraging and offshore deeper reefs suitable for egg survival. [ABSTRACT FROM AUTHOR]

In a warming climate, male sea turtles may become increasingly rare due to temperature-dependent sex determination with females being produced at warmer temperatures. Hence there is widespread concern that a lack of adult males may impact population viability. However, there is controversy over this scenario and here we review aspects of the biology of male sea turtles that will help mitigate female-biased hatchling sex ratios. In particular, there is strong evidence that males generally breed more frequently than females (i.e. have a shorter remigration interval) and that individual breeding males actively search for females and may mate with multiple females from different nesting sites. These aspects of the biology of male turtles will cause female-biased hatchling sex ratios to translate into more balanced adult sex ratios on the breeding grounds (i.e. operational sex ratios). Sexual dimorphism is widespread with adult male turtles generally being smaller than females. In freshwater turtles, this sexual dimorphism is linked to earlier age at maturity for males, although this possibility has not been examined widely in sea turtles. We make a forward-looking horizon-scanning prediction for key changes that might be expected at sea turtle breeding grounds if female-biased sex ratios become so extreme that male turtles start to become limiting and start driving populations to extinction. In particular, as the numbers of adult males on the breeding grounds become limiting there may be changes in egg fertility, multiple paternity and hatching success within clutches. [ABSTRACT FROM AUTHOR]

The Indian jumping ant Harpegnathos saltator is one of the most well-studied ant species; however, little is known about the biology and behavior of sister species in the genus. To understand the universality of the phenomena revealed in H. saltator, biological studies of closely related species are important. We investigated the nest architecture and colony reproductive structure of Harpegnathos venator at two sites in northern Thailand. Nests had chimney-like entrances with a funnel diameter of about 3 cm and consisted of two or three chambers, the floors of which were flat and smooth. The floors and walls inside the chambers were decorated with several small fragments of cocoons, which has been referred to as "wall-papering". Most colonies included one or more mated dealate queens that laid eggs, whereas only a few mated workers reproduced in the queenright colonies. In our sampling, virgin dealate queens were found in several colonies, but there were very few queenless colonies that reproduced by mated workers. Additional colonies collected from three other sites in Thailand also had dealate queens. The H. venator colonies reproduced mainly by mated queens, although many mated workers were present. The nest architecture of H. venator was similar to that of H. saltator, but the colony reproductive structure was different: queen colonies of H. saltator are always monogynous, and queenless colonies that reproduce by gamergates are frequently found. Furthermore, virgin dealate queens are never found in H. saltator. Factors affecting these differences between the two congeneric species are discussed. [ABSTRACT FROM AUTHOR]

Protogynous sex change has been widely reported as a life-history strategy in polygynous reef fish. Dascyllus reticulatus is known to form haremic colonial groups on branching corals and is thought to undergo protogynous sex change based on gonad histology. We conducted a 2-year underwater survey on 13 haremic groups to examine the sex-change patterns of D. reticulatus on reefs of southern Japan. We observed 11 instances of protogynous sex change. One involved a take-over sex change by the largest female following the disappearance of the dominant male. In other contexts, females undergo sex changes in the presence of males or larger females. These sex-change individuals commonly had limited mating opportunities as females. Of the ten sex changers, five subordinate females became bachelor males showing no sexual behavior despite their ability to release sperm. Owing to behavioral crypticity, these bachelor males remained within their groups without suffering attacks from territorial males. Furthermore, sex changers showed higher growth rates than females. Two bachelor sex changers subsequently obtained mating status, of which one became a female again after inter-group migration. It is suggested that female D. reticulatus often overcomes reproductively isolated situations via the growth advantages of protogynous sex change and sexual plasticity. [ABSTRACT FROM AUTHOR]

Many bird species migrate to southern overwintering locations to avoid harsh conditions at their breeding grounds, but at the cost of an energetically demanding migration that may delay their spring reproductive development. Previous work on the relationship between migration distance and reproductive readiness has primarily focused on early season baseline testosterone in both males and females. However, for females, testosterone alone may not be the appropriate measurement of reproductive development. Estradiol, a metabolite of testosterone that is essential for breeding behaviors and reproduction, should also be measured. Furthermore, baseline testosterone varies throughout the day and may change due to social interactions that occurred prior to sampling. Injection of gonadotropin-releasing hormone (GnRH) elicits an individual's maximum potential testosterone production, minimizing daily and social variation. We explored relationships between migration distance and reproductive status after arrival to the breeding ground in Red-winged Blackbirds (Agelaius phoeniceus). We predicted that individuals that travel a shorter distance will have higher levels of reproductive hormones upon arrival given they are able to invest less in migration and more in reproduction. This is important because individuals that breed earlier often have higher reproductive success. In females, we measured baseline estradiol and testosterone. In males, we assessed baseline and GnRH-induced testosterone. Hormone values were related to migration distance, estimated by stable isotope analysis of claw samples collected before breeding began in eastern North Dakota. We found that males with shorter inferred migration distances have higher baseline testosterone upon arrival. However, inferred migration distance was not correlated with GnRH-induced testosterone. Female inferred migration distance was not correlated with baseline testosterone, but it was correlated with baseline estradiol. Females with higher testosterone had lower estradiol, suggesting that testosterone in females is not a reliable indicator of estradiol levels, thus readiness to breed. Our observations suggest that baseline hormone levels were related to migration distance, but baseline testosterone alone may not provide a complete assessment of a male or female's preparedness to breed following spring migration. [ABSTRACT FROM AUTHOR]

Mating system theory predicts that social polygyny—when one male forms pair bonds with two females—may evolve by female choice in species with biparental care. Females will accept a polygynous male if the benefit of mating with a male providing high-quality genes or rearing resources outweighs the cost of sharing mate assistance in parental care. Based on this rationale, we hypothesise that the population frequency of social polygyny (FSP) varies due to changes in mate sharing costs caused by changing environmental conditions. We predicted that: (1) polygamous females (i.e. mated with a polygynous male) pay a survival cost compared to monogamous females; (2) FSP would be higher in years with better rearing conditions and (3) the difference in survival rates between monogamous and polygamous females would be small following years with higher FSP. We tested these predictions using regression and multistate analyses of capture-recapture data of pied flycatchers, Ficedula hypoleuca, in central Spain collected over 26 years (1990–2016). Monogamous females had a higher mean survival rate than polygamous females (prediction 1), but there was no difference in survival between polygynous and monogamous males. In addition, FSP was positively associated with annual reproductive success (a proxy of the quality of rearing conditions—prediction 2). Finally, following years with high FSP, the survival of polygamous females was similar to that of monogamous females (prediction 3), while the chance of breeding in a polygamous state for 2 years in a row increased for both males and females. Our findings suggest that fluctuating environmental conditions may be a necessary but neglected aspect of understanding social polygyny mechanisms. [ABSTRACT FROM AUTHOR]

Insect societies vary greatly in their social structure, mating biology, and life history. Polygyny, the presence of multiple reproductive queens in a single colony, and polyandry, multiple mating by females, both increase the genetic variability in colonies of eusocial organisms, resulting in potential reproductive conflicts. The co-occurrence of polygyny and polyandry in a single species is rarely observed across eusocial insects, and these traits have been found to be negatively correlated in ants. Acromyrmex leaf-cutting ants are well-suited for investigating the evolution of complex mating strategies because both polygyny and polyandry co-occur in this genus. We used microsatellite markers and parentage inference in five South American Acromyrmex species to study how different selective pressures influence the evolution of polygyny and polyandry. We show that Acromyrmex species exhibit independent variation in mating biology and social structure, and polygyny and polyandry are not necessarily negatively correlated within genera. One species, Acromyrmex lobicornis, displays a significantly lower mating frequency compared to others, while another species, A. lundii, appears to have reverted to obligate monogyny. These variations appear to have a small impact on average intra-colonial relatedness, although the biological significance of such a small effect size is unclear. All species show significant reproductive skew between patrilines, but there was no significant difference in reproductive skew between any of the sampled species. We find that the evolution of social structure and mating biology appear to follow independent evolutionary trajectories in different species. Finally, we discuss the evolutionary implications that mating biology and social structure have on life history evolution in Acromyrmex leaf-cutting ants. Significance statement: Many species of eusocial insects have colonies with multiple queens (polygyny), or queens mating with multiple males (polyandry). Both behaviors generate potentially beneficial genetic diversity in ant colonies as well as reproductive conflict. The co-occurrence of both polygyny and polyandry in a single species is only known from few ant species. Leaf-cutting ants have both multi-queen colonies and multiply mated queens, providing a well-suited system for studying the co-evolutionary dynamics between mating behavior and genetic diversity in colonies of eusocial insects. We used microsatellite markers to infer the socio-reproductive behavior in five South American leaf-cutter ant species. We found that variation in genetic diversity in colonies was directly associated with the mating frequencies of queens, but not with the number of queens in a colony. We suggest that multi-queen nesting and mating frequency evolve independently of one another, indicating that behavioral and ecological factors other than genetic diversity contribute to the evolution of complex mating behaviors in leaf-cutting ants. [ABSTRACT FROM AUTHOR]

The Northern chamois (Rupicapra rupicapra) is a weakly polygynous species widely distributed in the mountain regions of Europe and the Near East. The Balkan chamois (R. r. balcanica) occurs in the mountain regions of southeastern Europe, and its ecology and behavior during the rut are largely unknown, making it one of the most understudied subspecies of chamois. Despite the scarce body mass dimorphism, males display a developed behavioral polymorphism that affects the mating success and possibly survival. Here, we provide the first quantitative analysis of the behavioral repertoire and activity budget of rutting male Balkan chamois and compare frequencies of different behavioral categories (i.e., courtship and direct and indirect aggression) with those observed in Alpine (R. r. rupicapra) and Tatra (R. r. tatrica) chamois. Male Balkan chamois have a rich behavioral repertoire (24 different behavioral patterns) with a prevalence of courtship behaviors and a higher frequency of indirect than direct forms of aggression. Compared with Alpine and Tatra chamois, no significant difference in the frequency of different behavioral categories was detected. The activity budget showed that when not rutting, males spent ~ 41% of their time foraging and ~ 59% lying down. Time spent rutting was negatively correlated with time spent foraging and time spent lying down, suggesting that time spent for mating activities increased at the expense of foraging and resting. In dominant males, the frequency of courtship behavior was higher than the frequency of aggressive behaviors, whereas in subordinate males, no differences were detected among behavioral patterns. Furthermore, no significant differences in activity budgets were detected between male types. This is the first report of Balkan chamois rutting behavior and provides important insights into the ecology of a poorly known subspecies. [ABSTRACT FROM AUTHOR]

Trade-offs between reproductive effort and subsequent growth in males are not well explored, despite their relevance in questions of individual energy allocation. Regarding the growth of sexual secondary characters in polygynous breeding male mammals, indeed, no conclusive studies exist. We investigated in male Alpine ibex (Capra ibex) the relationship between their behavioral reproductive effort, current horn size, and subsequent horn growth. While controlling for age, no evidence was found for male behavioral reproductive effort during the rut being affected by their horn size. On the other hand, reproductive effort significantly decreased age-specific horn growth during the following summer. Our study provides evidence that growth of secondary sexual characters is traded against behavioral investments in reproduction in a male mammal. It bears important implications for the understanding of energy allocation between various life-history components and the evolutionary ecology of secondary sexual characters. [ABSTRACT FROM AUTHOR]

Polygyny is the most common mating system in mammals, and many species form uni-male multi-female groups (UM-MF units). Polygynous systems are traditionally distinguished according to male reproductive strategies, such as "resource defense" or "female defense," both of which are often described in the literature as forming "harems." However, this focus on male strategies, and the use of umbrella terms to describe them, lumps together societies that fundamentally differ in their ontogeny, stability, and relationships. Integrating foundational theories of mating strategies with the principles governing relationship dynamics, driven by both male and female strategies and modulated by male-female conflicts of interest, we propose a new framework for classifying the diversity of UM-MF units. We differentiate UM-MF groups in terms of average female kinship within the group and length of male tenure to define general classes with distinct predictions for the nature of inter- and intrasexual relationships. We propose a narrower definition for the "true harem" along with new terminology to describe the other three classes: "benign consortship," "coterie," and "coercive consortship." Using socioecological data for 40 mammalian species from 27 families, we found our framework was able to successfully predict patterns of female-female cooperation and the presence of coercive male-female relationships. Finally, we refine our framework, identifying subclasses of the main four classes and propose hypotheses about the underlying causes of observed patterns. By focusing on the nature of within group relationships, this framework provides a powerful lens for asking broad, comparative evolutionary questions about social evolution and socioecology. [ABSTRACT FROM AUTHOR]

The wool carder bee Anthidium manicatum is one textbook example of resource defense polygyny among solitary bees, known for intense male–male competition, forced copulations, and the extreme form of interspecific territoriality toward other flower visitors. This mating system depends on the spatial structure of the defended resource and requires several adaptations in males. The allocation of patches with host plants as well as male body size and phenology was analyzed over 3 years in the diverse habitat of a botanical garden. Anthidium manicatum males searched in groups up to 12 individuals a wide diversity of patches with various food plants of foraging females. Territories were established in small high-quality patches only. Males abandoned aggressive and territorial behavior in large patches. Available patches were occupied by males of the various body size fractions independently of each other according to patch profitability. The higher competitive weight of large males in small patches compared to spacious ones was balanced by an opposing correlation of patch profitability. Although the mating system in A. manicatum is clearly a resource defense polygyny, males were found to be plastic in their behavior, and territoriality was not consistently observed. Mate acquiring tactics, be they territory holder (bourgeois), sneaker, floater, or scrambler for mating, can be considered to be different behavioral phenotypes within one environmentally sensitive conditional strategy. Significance statement: Territoriality is a rare and derived pattern in solitary bee mating behavior. In most cases of territoriality, males defend rendezvous places to meet freshly emerged, virgin females. While this type of mating behavior fits still into the framework of ancestral monandry of aculeate Hymenoptera, the continually polyandric resource defense polygyny found in the genus Anthidium is highly derived. Males occupy flower resources exploited for larval provisions and extort copulations from provisioning nesting females. Territoriality in Anthidium does not lead to a monopolization of females, the exclusion of many competitors from reproduction, and a reduction of sperm competition as is typical for resource-based mating systems. Contrary, Anthidium is a highly promiscuous species and both males and females are lifelong engaged in copulations with multiple mates. Also, the allocation of the resource fundamental to the defense polygyny was found to be more fairly balanced than expected. This study diversifies the mating system of anthidiine bees and demonstrates unusually high plasticity in the resource allocation of a territorial species. [ABSTRACT FROM AUTHOR]

Males with damaged weapons often lose intraspecific contests; however, recent research suggests these males may use post-copulatory means to mitigate reduced reproduction. When intraspecific competition is absent, can weapon-damaged males produce more offspring in multi-mating scenarios relative to intact males? We examined the reproductive potential of weapon-damaged males in Narnia femorata (Hemiptera: Coreidae), a species that exhibits resource defense polygyny and is known to increase testes size when developmental weapon damage occurs. We induced weapon damage during development. Upon sexual maturation, we provided intact and weapon-damaged males with access to four unmated females successively and without any competitors. The mating partners of weapon-damaged males were more likely to have their eggs hatch. Furthermore, weapon-damaged males produced more offspring, though only with larger females. These results suggest that weapon-damaged males have enhanced fertilization outcomes, potentially minimizing reproductive costs of weapon damage. Significance statement: Weapon damage is common in nature and can reduce pre-copulatory success. However, few studies have examined the reproductive consequences of weapon damage. We tested the hypothesis that weapon-damaged males can compensate for a pre-copulatory disadvantage through increased investment in traits that improve post-copulatory fertilization success. To examine the reproductive potential of weapon-damaged males, we provided males with four females in succession, then measured reproductive outcomes. We found that mating partners of weapon-damaged males were more likely to have their eggs hatch relative to the mating partners of intact males. Furthermore, we found that weapon-damaged males produced a larger number of offspring than intact males. This evidence reveals that weapon damage allows males to boost reproductive outcomes in non-competitive contexts. [ABSTRACT FROM AUTHOR]

We investigated the mating system of three sex changing gobiid fishes: Priolepis akihitoi, Trimma emeryi, and Trimma hayashii by underwater observation or specimen collection. P. akihitoi were found in pairs or were solitary. As the pair bond persisted for at least two months, and pair individuals seemed to mate with each other repeatedly, a monogamous mating system was suggested in P. akihitoi. In contrast, the harem-like group (living in a group composed of one largest male and some smaller females and/or immature individuals) of T. hayashii and T. emeryi suggested that these species have harem polygyny. [ABSTRACT FROM AUTHOR]

Understanding fertility variation among women helps identify individuals and communities with high reproductive performance that slows fertility transition especially for African countries. The aim of this study was to investigate individual and community factors influencing lifetime fertility/children ever born (CEB) in Eswatini (formerly Swaziland). Using data from a onetime national representative demographic and health survey conducted in 2006–2007, this study goes beyond previous efforts by considering a broad range of individual and community factors that influences lifetime fertility and applying a supply–demand Easterlin–Crimmins model allowing for a multilevel framework. The results of a sequential multilevel (random intercept) Poisson regression suggest that the model was appropriate to account for overdispersed CEB data. All multilevel models found significant, but small, lifetime fertility variation across communities/clusters. While lifetime fertility variation decreased significantly from the empty model to the final model after controlling for a range of individual and community, it does not entirely disappear indicating the local community may have some bearing on CEB. Further, this suggests compositional (individual demographic and socioeconomic) factors explained substantial, but not all of the variation. At individual-level, the results suggest a significant negative association of household wealth index, level of education, age at sexual debut and age at first birth with CEB. On the other hand, the incident of childbearing among women increased significantly with child loss, having high fertility norms (5 or more children), being married, particularly in polygyny than monogamy unions, being employed and empowered. The compatibility of the latter two variables with childbearing contends with theory and warrants attention for future research. The results confirm the Easterlin–Crimmins model explain fertility behaviour reliably and demand (fertility norms) and supply (child loss) variables have good predictive value. At community level, women from rural communities had higher fertility than from urban ones. Overall, lifetime fertility in Eswatini is strongly related to individual (compositional) characteristics and is unique for urban–rural communities. [ABSTRACT FROM AUTHOR]

Background: Child mortality has become a prominent public health issue in sub-Saharan Africa (SSA). The mortality rates can in part be translated to how communities meet the health needs of children and address key household and environmental risk factors. Though discussions on the trends and magnitude of child mortality continue as to strategize for a lasting solution, large gap exists specifically in family characteristics associated with child death. Moreover, household dynamics of child mortality in SSA is under researched despite the fact that mortality rates remain high. This study aimed to examine the influence of household structure on child mortality in SSA. Methods: Secondary data from birth histories in recent Demographic and Health Survey (DHS) in 35 SSA countries were used in this study. The total sample data of children born in the 5 years prior to the surveys were 384,747 births between 2008 and 2017. Unadjusted and adjusted Cox proportional hazard regression model was fitted to model infant and under-five mortality. The measure of association was hazard ratio (HR) with 95% confidence interval (CI). Statistical test was conducted at p < 0.05 level of significance. Results: Total infant mortality rates were highest in Sierra Leone (92 deaths per 1000 live births), Chad (72 deaths per 1000 live births) and Nigeria (69 deaths per 1000 live births), respectively. Furthermore, total rates of under-five mortality across 35 SSA countries were highest in Cameroon (184 deaths per 1000 live births), Sierra Leone (156 deaths per 1000 live births) and Chad (133 deaths per 1000 live births). The risk of infant mortality was higher in households of polygyny, compared with households of monogyny (HR = 1.23; CI 1.16, 1.29). Households with large number of children (3–5 and ≥ 6) had higher risk of infant mortality, compared with those with 1–2 number of children. Infants from mothers with history of multiple union had 16% increase in the risk of infant mortality, compared with those from mothers from only one union (HR = 1.16; CI 1.09, 1.24). Furthermore, under-five from female household headship had 10% significant reduction in the risk of mortality, compared with those from male household headship (HR = 0.90; CI 0.84, 0.96). The risk of under-five mortality was higher in households of polygyny, compared with monogyny (HR = 1.33; CI 1.28, 1.38). Households with large number of children (3–5 and ≥ 6) had higher risk of under-five mortality, compared with those with 1–2 number of children ever born. Under-five from mothers with history of multiple union had 30% increase in the risk of mortality, compared with those from mothers from only one union (HR = 1.30; CI 1.24, 1.36). Conclusion: Household structure significantly influences child mortality in SSA. Knowledge of drivers of infant and child death is crucial in health policy, programmes designs and implementation. Therefore, we suggest that policies to support strong healthy families are urgently needed to improve children's survival. [ABSTRACT FROM AUTHOR]

Animals are predicted to prefer high-quality over low-quality habitats, but adaptive habitat selection is less straightforward than often assumed. Preferences may improve only specific fitness metrics at particular spatial scales, with variation across time or between sexes. Preferences sometimes even reduce fitness. We investigated the context specificity of adaptive habitat selection, studying dickcissels (Spiza americana)—a polygynous songbird—as a model. From 2014 to 2015, we measured male and female habitat preferences at two scales (territories and landscape patches) on 21 grassland patches in Ringgold County, Iowa, USA. We tested whether preferences improved four fitness metrics—polygyny, avoidance of brood parasitism by brown-headed cowbirds (Molothrus ater), fledgling productivity, and offspring condition. Both sexes preferred territories where offspring attained superior condition and patches where parasitism was infrequent. Females preferred patches where nests produced more fledglings, and in 2014, males on preferred (i.e., early-established) territories attracted more mates and produced more fledglings. However, males on non-preferred (i.e., late-established) territories were more successful in 2015. This inconsistency may have arisen because females were abundant and nest-predation rates were low in May–June 2014, allowing early-settling males to produce many young. In 2015, however, females were more abundant and nests more successful later in the breeding season. Our results show that habitat preferences do not uniformly improve fitness, and some benefits differ between sexes. Moreover, preference–fitness relationships only manifest at specific scales, and annual variation in population and predation dynamics can limit consistency. Detecting adaptive habitat selection thus requires multi-year measurements and careful consideration of relevant scales. [ABSTRACT FROM AUTHOR]

Nest-founding in the fungus-growing ant Mycocepurus smithii is typically by single queens (monogyny) and colonies transition to multiple queens (polygyny) as they grow larger. Here, we study the transition from monogyny to polygyny of M. smithii under lab conditions. We hypothesize that the worker-to-queen ratio affects colony growth, fungus-garden growth, and colony survival. Monogyne colonies with small gardens (0.1 g) had greater garden growth than polygyne colonies, suggesting that monogyny may be the superior strategy for small colonies after initial nest establishment. In monogyne colonies with small gardens and either 30, 60, or 90 workers, colonies with 60 workers produced the largest gardens, suggesting that an intermediate worker-to-queen ratio is optimal for monogyne colonies with small gardens. For monogyne colonies with larger gardens (0.45 g) and with either 6, 18, 60, or 90 workers, colonies with 60 or 90 workers had significantly greater garden growth than those with 6 or 18 workers. New daughter queens were produced only by colonies with a worker-to-queen ratio of 60 or 90, suggesting that only colonies with sufficient worker numbers and garden growth are stimulated to produce new queens. A single queen lays only 1.12 ± 0.06 (SE) eggs within 24 h, therefore, limiting growth of monogyne colonies. The transition from monogyny to polygyny through the addition of supernumary queens, as well as a worker-to-queen ratio of around 60, are, therefore, critical for colony growth and reproduction in M. smithii. [ABSTRACT FROM AUTHOR]

The polygyny threshold model predicts that a female chooses an already-mated male if the direct benefits of higher territorial quality compensate for the cost of mate sharing. The sexy son hypothesis (SSH) expands this framework from direct to indirect benefits assuming that polygynously-mated females give birth to sexy and subsequently polygynous sons. Although the SSH has generated much debate, empirical evidence is inconclusive. I argue that lack of support could be related to the SSH formulation of the polygyny threshold as a population-level mechanism making the female choice of a polygynous male either advantageous or disadvantageous regardless of any other difference between potential mates. Using a simulation approach, I show that individual variation in males' quality should be considered because, otherwise, the empirical validation of the hypothesis is hampered, giving rise to patterns that are apparently irreconcilable with the SSH predictions. [ABSTRACT FROM AUTHOR]

The study of the social organization of ants may help to understand why some species are able to persist in natural forests after fragmentation and anthropogenic disturbances. The Neotropical ant Gnamptogenys bisulca has shown to be a biological indicator of habitat quality in Andean montane forests and we proposed to explain this characteristic by investigating its social structure and the spatial distribution of colonies at fine scale. In eight 100 m2 plots located in four forests in the western Colombian Andes, the position of G. bisulca colonies was recorded for spatial distribution and their social composition described: ergatoid females were found in most of the nests, isolated or together with normal queens. As ergatoids and queens were dissected to examine their reproductive status, it appeared that apparent polygyny represented, in fact, effective monogyny, with other potential reproductive females being unmated or inhibited. In the few cases of mixed colonies, a queen was always at the head of the colony. Local spatial distribution was random and did not fit the hypothesis of nesting by fission, as generally observed in the case of the presence of ergatoids. However, the social structure was significantly different according to the site, the most preserved forest showing no or rare ergatoids (but queens) compared to the other sites. Our results indicated that the presence of ergatoids in G. bisulca may help colonies to adapt to slightly disturbed habitat contexts. [ABSTRACT FROM AUTHOR]

The dynamic sea ice habitat of polar bears (Ursus maritimus) influences their mating behaviour because it makes the distribution of mates unpredictable. Pronounced sexual dimorphism of polar bears likely results from a polygynous mating system, where intrasexual competition between males influences reproductive access to females. We examine aspects of the mating behaviour of polar bears in the Beaufort Sea, Canada, from 1970 to 2014 based on 135 breeding pairs observed from March through May. Mean age of paired females and paired males was 9.7 and 11.5 years, respectively. Paired males were older (by 2.2 years) and had significantly higher mass (71 kg) than unpaired males suggesting a polygynous mating system in which larger, dominant, and potentially experienced males monopolise access to females. Our binomial logistic regression suggested age was the most important factor in predicting pairing in males, which can be explained by the correlation between age and body size. Paired females had significantly higher labial development than lone females, suggesting that labial swelling is heightened during mating. Taken together, these observed characteristics suggest a polygynous mating system in polar bears, providing further insight into potential mating system variation across their range. [ABSTRACT FROM AUTHOR]

In geographic regions with warm winters, invasive yellowjacket wasp colonies (genus Vespula) often exhibit polygyny (multiple queens) and persist for multiple years, despite these phenomena being rare in the native range. Here, we test the hypothesis that polygyny, caused by foreign queens being accepted into an existing colony, is the result of relaxed nestmate recognition in the invasive range, as has been observed in some supercolonial invasive ants. In bioassays with wild colonies in the field, we found that nestmate discrimination was weak in both invasive (Hawaii) and native (California) populations of Vespula pensylvanica, with significant nestmate discrimination in only ~ 30% of trials. We also found that the diversity and variability of cuticular hydrocarbons, chemical compounds that mediate nestmate recognition, were not reduced in introduced populations, unlike several supercolonial invasive ant species. Our findings suggest that ancestral weak nestmate discrimination behavior of V. pensylvanica may make this species pre-adapted to transition to polygyny and extended colony lifespans when introduced into environments with benign winters that facilitate foreign queens joining existing colonies in late season. [ABSTRACT FROM AUTHOR]

Annual variation in the frequency of polygyny in the European pied flycatcher population is determined by a set of factors, with the primary factor being the sex ratio at the onset of the breeding season. The remaining factors, including individual characteristics of male and environmental conditions during this period, played a significant but secondary role. Facultative polygyny should be viewed as a mechanism to support the highest possible breeding productivity of individuals and populations, in unstable environmental conditions. It prevents an occurrence of nonbreeding females ready for mating and provides them with an opportunity to participate in breeding at a optimal time. [ABSTRACT FROM AUTHOR]

Polygyny in mammals, as in other groups, is related to sexual dimorphism, with males being larger than females or with elaborate weaponry as a response to sexual selection. However, sexual selection can also act on females, leading to cases where dimorphism is reversed or absent and females mate with several males, leading to a promiscuous mating system. In this study, we analyzed the mating system of a monomorphic mammalian species, the white-lipped peccary ( Tayassu pecari ), using microsatellite molecular markers and parentage tests. The white-lipped peccary mating system is predicted to be polygyny, but so far, no systematic study exists. To verify their mating behavior, 131 individuals of a herd from the Brazilian Pantanal were genotyped for 11 microsatellite loci and parentage tests were performed for all the sampled young. We determined that both males and females had offspring with more than one partner which is compatible with a promiscuous mating system. Promiscuity in this species could be related to competition among females as a result of the female-biased sex ratio leading to sexual and/or natural selection not only on males but also females. [ABSTRACT FROM AUTHOR]

Mate guarding has been known to incur costs and cause constraints for harem males in many polygynous species. However, the effect of female group size on the harem male's time budget in bats has received very limited attention. The Indian short-nosed fruit bat, Cynopterus sphinx, exhibits resource defense polygyny, in which tent roosting males construct tents and defend multiple female bats. We studied the effect of female group size on three aspects of harem male behavior: social grooming by reciprocal licking, tent maintenance, and tent guarding in the mast tree Polyalthia longifolia. In the process of reciprocal licking, all the bats in the harem were drenched in saliva before emergence, and this activity was positively and significantly correlated with female group size. Once females departed for foraging, harem males remained in their respective tents at night-time between intermittent foraging bouts and engaged in tent maintenance and tent guarding. Time invested by harem male bats in tent maintenance and tent guarding were positively and significantly correlated with female group size. Harem males extended their presence in tent by utilizing tents as feeding roosts. Female group size also influenced the emergence time of harem male bats, where males with largest group emerged later than did the smallest group. Likewise, harem male with the smallest group had more time available for foraging than the male with the largest group. Findings of this study suggest that having a larger harem may indeed be costly for the males by reducing their foraging time. [ABSTRACT FROM AUTHOR]

Horses are phylogenetically distant from primates, but considerable behavioral links exist between the two. The sociality of horses, characterized by group stability, is similar to that of primates, but different from that of many other ungulates. Although horses and primates are good models for exploring the evolution of societies in human and non-human animals, fewer studies have been conducted on the social system of horses than primates. Here, we investigated the social system of feral horses, particularly the determinant factors of single-male/multi-male group dichotomy, in light of hypotheses derived from studies of primate societies. Socioecological data from 26 groups comprising 208 feral horses on Serra D'Arga, northern Portugal suggest that these primate-based hypotheses cannot adequately explain the social system of horses. In view of the sympatric existence of multi- and single-male groups, and the frequent intergroup transfers and promiscuous mating of females with males of different groups, male-female relationships of horses appear to differ from those of polygynous primates. [ABSTRACT FROM AUTHOR]

Our understanding of animal mating systems has changed dramatically with the advent of molecular methods to determine individuals' reproductive success. But why are older behavioral descriptions and newer genetic descriptions of mating systems often seemingly inconsistent? We argue that a potentially important reason for such inconsistencies is a research trajectory rooted in early studies that were equivocal and overreaching, followed by studies that accepted earlier conclusions at face value and assumed, rather than tested, key ideas about animal mating systems. We illustrate our argument using Anolis lizards, whose social behavior has been studied for nearly a century. A dominant view emerging from this behavioral research was that anoles display strict territorial polygyny, where females mate with just the one male in whose territory they reside. However, all genetic evidence suggests that females frequently mate with multiple males. We trace this mismatch to early studies that concluded that anoles are territorial based on limited data. Subsequent research assumed territoriality implicitly or explicitly, resulting in studies that were unlikely to uncover or consider important any evidence of anoles' departures from strict territorial polygyny. Thus, descriptions of anole behavior were largely led away from predicting a pattern of female multiple mating. We end by considering the broader implications of such erratic trajectories for the study of animal mating systems and posit that precise definitions, renewed attention to natural history, and explicitly questioning assumptions made while collecting behavioral observations will allow us to move towards a fuller understanding of animal mating systems. Significance statement: Mismatches between behavioral and genetic descriptions of mating systems are widespread across animals. We argue that these discrepancies can arise from the erratic and contingent progression of research on space use behavior and social interactions. We demonstrate such a trajectory in Anolis lizards, where decades of behavioral data led not only to the conclusion that anoles are territorial but also to the erroneous expectation, disproven by genetic evidence, that each female mates with just one male. The earliest studies concluded that anoles are territorial based on flimsy evidence, leading subsequent studies to implicitly and explicitly assume territorial behavior; later studies were thus unlikely to detect, or consider important, departures from territoriality that could facilitate female multiple mating. Such research trajectories are likely not unique to anoles, and we contend that avoiding these trajectories requires renewed and continued attention to the natural history of even well-studied organisms. [ABSTRACT FROM AUTHOR]

While colonies of most tropical species of the ant genus Cardiocondyla regularly contain multiple egg-laying queens (polygyny), single-queening (monogyny) evolved convergently in a Palearctic clade of Cardiocondyla and in Southeast Asian C. ' argyrotricha.' In the latter species, monogyny is probably an adaptation to patchily distributed but highly stable nest sites. In experimentally orphaned colonies of C. ' argyrotricha,' the first emerging queen shed its wings, began to lay eggs, and stayed mostly on the brood pile. Queens that emerged later remained in the peripheral areas of the nest without dispersing but retained their wings even after mating in the nest. Aggressive interactions among queens and between workers and queens were occasionally observed, but it appears that the order of queen emergence determines which of them will become reproductive and inherit the nest. We conclude that young queens commonly compete for nest inheritance in some species of Cardiocondyla and that queen-queen antagonism does not necessarily involve lethal fighting. [ABSTRACT FROM AUTHOR]