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Copyright of Ardeola is the property of Sociedad Espanola de Ornitologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The growing demand for insect mass production requires methodologies that allow for easy separation of males and females as the two sexes can have very different economic values. The common housefly, Musca domestica (L.) (Diptera: Muscidae), is one of the candidate species for industrial production. In this species, males typically develop faster and are smaller than females. Exploiting housefly sexual bimaturism (sexual difference in developmental time) could allow the maintenance of colonies with a higher proportion of females, which is favourable in terms of egg yield. Here, we report an artificial selection experiment of breeding early‐emerging males with late‐emerging females for six generations, with the aim to increase the time interval between emergence of males and females. The level of sexual bimaturism was not increased after six generations of selection. The life‐history traits fecundity, egg‐to‐adult survival and hatchability were not affected by the selection procedure. Wing size measurement revealed that early‐ and late‐emerging males did not differ in size, suggesting that developmental time and body size are decoupled in this sex. Still, large females consistently emerged later than small females, suggesting an intricate sex‐specific genetic architecture for size and developmental time in the housefly. Our results are relevant in the context of mass production, providing new insight into the manipulation and maintenance of female‐biased sex ratios in production colonies of the common housefly. [ABSTRACT FROM AUTHOR]

The temporal separation of male and female flowering—known as dichogamy—is a widespread adaptation across the plant kingdom that increases reproductive success and enhances plant fitness. Differences in timing between male and female flowering can be highly sensitive to environmental variation—and with widespread evidence of shifts in seasonal timing of flowering (i.e., phenology) due to anthropogenic warming—climate change may alter the sequences of male and female flowering for a diversity of taxa around the globe. However, we currently lack a broad understanding of both the extent to which climate change may alter patterns of dichogamy and the potential implications of these shifts for plant reproduction. Here I present evidence that links variation in dichogamy to variation in temperature for a variety of plant taxa. I synthesize the limited number of studies that have investigated shifts in dichogamy specifically in the context of climate change, and detail the physiological, genetic, and developmental factors that control the relative timing of male and female flowering. The literature indicates that dichogamy is highly plastic and sensitive to temperature variation. Plasticity in dichogamy is observed across species with different sexual systems and growth habits, and in both female‐first and male‐first flowering taxa, but at present, no clear patterns of dichogamy shifts related to these associated traits are discernible. Together, these lines of evidence suggest that sequences of male and female flowering are likely to shift with climate change. However, more research is needed to better understand and predict the ecological consequences of shifting patterns of dichogamy in the context of global change. [ABSTRACT FROM AUTHOR]

In spring, many migrating songbirds exhibit protandry (the phenomenon whereby males precede females in arrival at breeding sites). The reed bunting (Emberiza schoeniclus) is a short-distance European migrant which expresses a high degree of protandry and combines both nocturnal and diurnal movements during migrations. In experimental conditions, we studied the proximate mechanisms of protandry and compared locomotor behavior between spring and autumn migrations. We assumed that captive behavior is a proxy for the behavior that birds demonstrate in the wild. Combined, the analysis of seasonal patterns and circadian dynamics of locomotor activity suggested that male reed buntings depart from wintering grounds by daytime flights approximately two weeks earlier than females. Later, they develop nocturnal activity, take off shortly before dawn and continue their flight for several hours in the morning. We argue that such behavior allows males to benefit from both the advantage of nocturnal flight and an efficient start of foraging, thereby reducing the stopover duration (by minimizing search/settling costs) and increasing the total migration speed. In contrast, females express predominantly nocturnal migratory activity in spring. We observed that in spring males had lower fat reserves compared to females. We suggest that males can forage during diurnal movements and therefore do not need to store large energetic reserves. In contrast, in autumn, both sexes display similar patterns of locomotor activity and fat reserves. Overall, our results describe unique sex-specific migratory behaviour and physiology in reed buntings in spring, which, we assume, contribute to spring arrival protandry in this species. Significance statement: To reach their destinations, migratory bird species adopt specific strategies reflected in behavior and/or physiology. In many species, males arrive earlier to the breeding grounds (a phenomenon called protandry). Knowledge of migratory strategies in species that experience both nocturnal and diurnal flights is scarce. To study the mechanisms that lead to protandry in nocturnal/diurnal migrant, we kept reed buntings (Emberiza schoeniclus) under experimental conditions that mimicked changes in photoperiod experienced by free-living birds from autumn migration through wintering to spring migration and recorded the dynamics of their locomotor activity and fat reserves. In spring, we observed sex differences in the seasonal patterns and circadian dynamics of locomotor activity and in the levels of fat reserves. We argue that such sex-related variation in behavior and physiology likely serves as proximate mechanisms for spring arrival protandry in reed buntings. [ABSTRACT FROM AUTHOR]

Female-biased sexual size dimorphism reaches an extreme in the genus Trichonephila Dahl, 1911 (Araneae: Nephilidae). Large female size is accomplished through the addition of juvenile instars and is likely the result of fecundity selection. However, additional instars in only one sex could result in significant developmental asynchrony. To minimize asynchrony, males should grow more slowly and females more rapidly. To test this prediction, we reared spiders from six disjunct populations of Trichonephila clavipes (Linnaeus, 1767) on three different diets, inducing variation in growth rates. Males on all diets grew more slowly than females, but still matured significantly earlier. In the field, mature males cohabit with juvenile females, and in the laboratory, mean male age at maturity corresponded to the age at which females achieve the minimum size observed to host males. However, a significant fraction of males mature earlier than concurrently-emergent females reach that minimum size—and before any females reached sexual maturity. Thus, early-maturing males may perish before reproducing, especially in temperate environments. We propose that (1) sexual size dimorphism and early male maturation evolved in tropical environments characteristic for T. clavipes, where adult females are found all year round. Univoltinism is likely a secondary trait in highly seasonal environments. Seasonal populations are likely mixes of local individuals and recent tropical immigrants, which could mitigate the loss of early males and retain this apparently maladaptive trait outside the tropics. (2) Environmental variation generates asynchronous emergence at the beginning of the growing season, allowing later-emergent males to mate with early-emergent females. [ABSTRACT FROM AUTHOR]

Several populations of a species of death camas (Anticlea elegans) (Melanthiaceae) were found growing and flowering above treeline in the remote Lemhi Mountains of southeastern Idaho USA. The predominant floral visitors were flies representing four families, particularly the Syrphidae. Many individual flies bore visible loads of Anticlea pollen. Various native bees were seen foraging in the locale, but all visited flowers other than Anticlea. The flies, as well as ants, fed from the tepal nectaries. Despite the plant’s common name, no foragers appeared to be impaired by imbibing its nectar. High in a neighbouring mountain range, A. elegans was being used as a trysting site by numerous Tenthredo sawflies. This is the first report of floral visitors to any Anticlea and among the first for any wildflower population above treeline in the vast US Intermountain West.

Seasonal animal dormancy is widely interpreted as a physiological response for surviving energetic challenges during the harshest times of the year (the physiological constraint hypothesis). However, there are other mutually non-exclusive hypotheses to explain the timing of animal dormancy, that is, entry into and emergence from hibernation (i.e. dormancy phenology). Survival advantages of dormancy that have been proposed are reduced risks of predation and competition (the ‘life-history’ hypothesis), but comparative tests across animal species are few. Using the phylogenetic comparative method applied to more than 20 hibernating mammalian species, we found support for both hypotheses as explanations for the phenology of dormancy. In accordance with the life-history hypotheses, sex differences in hibernation emergence and immergence were favored by the sex difference in reproductive effort. In addition, physiological constraint may influence the trade-off between survival and reproduction such that low temperatures and precipitation, as well as smaller body mass, influence sex differences in phenology. We also compiled initial evidence that ectotherm dormancy may be (1) less temperature dependent than previously thought and (2) associated with trade-offs consistent with the life-history hypothesis. Thus, dormancy during non-life-threatening periods that are unfavorable for reproduction may be more widespread than previously thought.

In many migratory songbirds, males arrive earlier at stopover sites and at the breeding grounds ('protandry') and older birds precede younger ones, but less is known about age differences in protandry. In seasonal environments, differential timing by sex and age is thought to reflect selection imposed by seasonality (i.e., viability selection) and intrasexual competition for space and mates. Viability and sexual selection can also favor male-biased sexual size dimorphism (SSD), leading to a positive relationship between protandry and SSD among species. We evaluated whether the relationship between protandry during spring migration and SSD in wing length (SSDW) differed between age classes in 20 sexually dimorphic songbirds. Consistent with the hypothesis that older, higher-quality males can better afford to arrive early, we found a stronger relationship between protandry and SSDW among older birds than among first-time breeders. We also tested the relationship between protandry and sexual size dimorphism of the wingtip (SSDWT) and found that greater age differences in protandry were related to greater age differences in SSDWT. We conclude that larger body sizes, energetically efficient wing shapes, and experience together select for the earlier arrival timing of older males relative to first-time breeding males and females. [ABSTRACT FROM AUTHOR]

Females and males may have distinct phenotypic optima, but share essentially the same complement of genes, potentially leading to trade-offs between attaining high fitness through female versus male reproductive success. Such sexual antagonism may be particularly acute in hermaphrodites, where both reproductive strategies are housed within a single individual. While previous models have focused on simultaneous hermaphroditism, we lack theory for how sexual antagonism may play out under sequential hermaphroditism, which has the additional complexities of age-structure. Here, we develop a formal theory of sexual antagonism in sequential hermaphrodites. First, we construct a general theoretical overview of the problem, then consider different types of sexually antagonistic and life-history trade-offs, under different modes of genetic inheritance (autosomal or cytoplasmic), and different forms of sequential hermaphroditism (protogynous, protoandrous or bidirectional). Finally, we provide a concrete illustration of these general patterns by developing a two-stage two-sex model, which yields conditions for both invasion of sexually antagonistic alleles and maintenance of sexually antagonistic polymorphisms. [ABSTRACT FROM AUTHOR]

Desynchrony of phenological responses to climate change is a major concern for ecological communities. Potential uncoupling between one of the most fundamental divisions within populations, males and females, has not been well studied. To address this gap, we examined sex-specific plasticity in hibernation phenology in two populations of Columbian ground squirrels (Urocitellus columbianus). We find that both sexes display similar phenological plasticity to spring snowmelt dates in their timing of torpor termination and behavioural emergence from hibernation. As a result of this plasticity, the degree of protandry (i.e. males' emergences from hibernation preceding those of females) did not change significantly over the 27-year study. Earlier male behavioural emergence, relative to females, improved the likelihood of securing a breeding territory and increased annual reproductive success. Sexual selection favouring earlier male emergence from hibernation may maintain protandry in this population, but did not contribute to further advances in male phenology. Together, our results provide evidence that the sexes should remain synchronized, at least in response to the weather variation investigated here, and further support the role of sexual selection in the evolution of protandry in sexually reproducing organisms. [ABSTRACT FROM AUTHOR]

The timing of flowering is central to plant life‐history as it initiates sexual reproduction, thus controlling plant interaction with pollinators and climate factors. A fundamental question is: what are the drivers of flowering time strategy in a species?We assembled mean flowering times for the indigenous dicotyledonous flora of New Zealand (n = 1303 species, including 177 tree species) and used phylogenetic models to determine how climate, plant traits, and evolutionary history (phylogeny) controlled interspecific variation in flowering times across an island flora.Across all species, on average, flowering was 19 days earlier in abiotically pollinated species relative to biotically pollinated species, 23 days earlier in woody species, relative to herbaceous species, 45 days earlier in species with fleshy‐fruits, relative to species with dry fruits and 31 days earlier in gender dimorphic species, relative to cosexual species. Species in warmer and drier climates flowered earlier than those growing under cool, moist climates.When all factors were considered together, the strongest influence on flowering time was sexual system: gender dimorphic species flowered earlier than cosexuals, even after accounting for other factors.Synthesis. We propose that these differences in flowering time arise because of sexual selection for early male flowering and sexual conflict between male and female individuals. As sexual selection and conflict may be stronger in gender dimorphic species than in cosexual species, our study suggests that plant sexual system is an important force structuring the phenology of plant communities, with potential consequences for ecological interactions and ecosystem processes. [ABSTRACT FROM AUTHOR]

• Tritoniopsis parviflora has three different floral rewards to attract pollinators. • The protandrous flowers secreted oil and nectar temporally segregated. • None of the oil bees predicted were observed on flowers along geographical distribution. • The potential bi-modal pollination system did not ensure high reproductive rates. Pollination in the South African species Tritoniopsis parviflora is of particular interest as it is the only oil-producing member of Iridaceae outside the Americas and the only species in the family known to secrete both floral oil and nectar. We evaluated oil and nectar secretion dynamics of T. parviflora, identified floral visitors and characterized their foraging behavior, and quantified reproductive success. Chemical and anatomical analyses suggest temporal segregation in rewards offered in male and female phases of the protandrous flowers. The diacetin amount was vestigial and none of the bees observed on flowers were specialist oil-collecting bees. Fruit set in the four studied populations was very low (c. 16 % of flowers). These results suggest that the T. parviflora pollination may be ensured by different functional bee groups and the visits by nectar-feeding and pollen-collecting bees may have been supplementary for seed production in the study period in conditions of low abundance of oil bees. The diversity of rewards in T. parviflora may serve as a form of bet-hedging that allows for pollination by generalist bees in the face of unreliable pollination service by specialist oil-collecting bees. [ABSTRACT FROM AUTHOR]

Documenting and understanding sex-specific variation in migratory phenology is important for predicting avian population dynamics. In spring, males often arrive on the breeding grounds before females (protandry), though whether these patterns result from fitness benefits vs. sexspecific constraints on arrival timing remains poorly understood. Sex-specific variation in the timing of fall migration is less well-documented than in spring, in part because documenting fall departures is often limited by cryptic behaviors, lower vocalization rates, and shifting territory boundaries during this time of year. We used 2 years of high-resolution encounter data from radio-frequency identification (RFID)-equipped bird feeders to monitor the daily presence of male and female Lazuli Buntings (Passerina amoena) throughout the breeding season at a high and a low-elevation site in Cache County, Utah, USA. These encounter data were used to estimate daily arrival and departure probabilities and to investigate possible differences in migration timing in relation to sex and elevation. At low elevation, male arrival (n = 15) preceded female arrival (n = 16) by ~1 week, consistent with previous research that has documented protandry in other migratory songbirds. At high elevation, however, no significant differences were found between male (n = 19) and female arrival (n = 6). In fall, we found little difference in departure dates between elevation or sex, or between years. Our observations are most consistent with constraint-based hypotheses explaining protandry, possibly relating to sex-specific constraints operating during the nonbreeding period. We additionally emphasize the need for quantifying uncertainty in phenological estimates and importance of addressing potential differences across demographic groups. [ABSTRACT FROM AUTHOR]

Euonymus americanus is a common understory shrub in mesic deciduous forests of eastern North America. Its inconspicuous greenish-white flowers appear in late April and May and are regularly visited by several species of ants and, by night, a species of cockroach. Because the species is self-compatible, these pollinators need not move between plants to effect fertilization and fruit-set. Flowers last for three days and are strongly protandrous with little if any overlap of male and female function. Based on a survey of five years of reports on iNaturalist in Georgia, Prenolepis imparis is the most commonly observed ant, followed by Camponotus pennsylvanicus and Crematogaster lineolata, though Camponotus castaneus was more common than the latter two species at our study sites. Each of these species was found to carry many viable pollen grains, as was a species of cockroach (Cariblatta lutea). Exclusion of ants from flowers resulted in near-zero fruit-set. Nevertheless, addition of pollen increased fruit-set significantly over open-pollinated levels, indicating pollen limitation. The upper limit in terms of potential seeds per fruit is 30, representing six seeds in each of the five locules of a mature capsule, but the average number of seeds per capsule was only 12. Seed viability was high, exceeding 95%. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Ecology is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The evolution and expression of floral traits are responsive to selection pressure from biotic and abiotic factors. Although floral traits significantly vary among environments, the flower remains unchanged. We aimed to understand the adaptation of Epimedium chlorandrum of floral traits to a frequently nocturnally rainy and wet environments and the roles of floral traits in pollination and reproduction. We observed flowering phenology, measured floral characteristics including the number of pollen grains and ovules per flower, measured pollen viability and stigma receptivity, tested the volume and sugar concentration of nectar and conducted flower-visit observations in this species. Different pollination treatments were performed to characterize the breeding system. The inner sepals and highly curved longer spurs of E. chlorandrum jointly formed an umbrella that shielded the anthers and stigma from rain wash and prevented nectar dilution. Epimedium chlorandrum was visited by six species, while Bombus trifasciatus was the only effective pollinator and fed on the nectar. One flower secreted approximately 17.06 µL of nectar with a 29.19 g/100 mL sugar concentration, and the pollination efficiency of B. trifasciatus was positively associated with the nectar sugar concentration. The self- and open-pollination treatments resulted in fewer fertile seeds than the cross-pollination treatment. In contrast, the autonomous self-pollination treatment failed to yield fertile seeds. In summary, pollen limitation caused by harsh weather and pollinator shortage occurred during the pollination process of E. chlorandrum , which was partially alleviated by self-compatibility. [ABSTRACT FROM AUTHOR]

Opisthopappus is a perennial, endemic herb of the Taihang Mountains in China. Two species of this genus (O. longilobus and O. taihangensis) are important wild genetic resources for Asteraceae; however, their reproductive biology has been lacking until now. This study is the first detailed report on the reproductive biology and breeding systems of two Opisthopappus species. Through field observations, the floral syndromes of O. longilobus and O. taihangensis were found to possess a similar pattern, although O. taihangensis has a relatively larger capitulum, more ray ligules, and disc florets. The flowers of both O. longilobus and O. taihangensis are protandrous, a character that can prevent autogamy at the single-flower level, and insects are required for pollination. Further, brightly ligules, brightly bisexual florets, unique fragrance, and amount of nectar suggest that these species propagate via an entomophilous pollination system. Hymenopteran and Diptera species were observed as the effective pollinators for these two species. The outcrossing index, pollen/ovule ratio and the results of hand pollination indicated that these Opisthopappus species might have a mixed mating system that combines cross-fertilization and partial self-fertilization for O. longilobus and O. taihangensis, outcrossing predominated in the breeding system, while self-pollination played an important role in seed production when insect pollination was unavailable, particularly in a harsh environment, such as the Taihang Mountains cliffs. Meanwhile, O. taihangensis might better adapt to severe surroundings with relatively complex floral syndromes, specifically through the attraction of visiting insects and a high seed set rate. The above results not only provide reference information toward a better understanding of the survival strategies of O. longilobus and O. taihangensis in the Taihang Mountains but also lay a solid foundation for further exploring the molecular mechanisms that underly their adaptation under cliff environments. [ABSTRACT FROM AUTHOR]

The reproductive ecology of the gobiid Trimma taylori is investigated using combined field sampling and rearing experiments. In captivity this species maintains continuous pair bonds, with male–female pairs repeatedly spawning. Gonads comprise simultaneous ovary, testis, and accessory gonadal structures. Thus, we infer that this species is capable of sex change in both directions. However, females from several sample populations from Amami Island, Japan, are larger than males, and male-to-female sex change may occur. We regard this species to be monogamous, and, despite possible bidirectional sex change, for it to possibly have a protandrous-like sexuality. [ABSTRACT FROM AUTHOR]

In seasonal environments, competition among males can drive males to emerge before females. Females, simultaneously, should avoid emerging at times after sufficient male availability. We show that the consequent sexual conflict over timing traits can produce arms races toward ever earlier emergence, if low mate-search efficiency or sperm limitation elevate the latter risk for females. In reality, however, arms races over timing cannot proceed indefinitely as this ignores the relevant ecological context for phenology: the temporal niche of resource availability for offspring development. We model the interaction of natural and sexual selection to predict the sexual conflict load, i.e. the loss of population fitness caused by sexual conflict. We show that selection to avoid matelessness can exacerbate another problem of maladaptation: a temporal mismatch between the organism (e.g. insect) and its resource (e.g. host plant). Load frequently associates with protandry if males can mate multiply, yet lack of multiple mating does not imply zero load. A temporal mismatch can still evolve, where both sexes emerge and mate suboptimally early with respect to the seasonal resource peak, because monogamy does not guarantee that every individual finds one mate, and selection favors early individuals in mate-finding contexts. [ABSTRACT FROM AUTHOR]

Advances in spring migratory phenology comprise some of the most well‐documented evidence for the impacts of climate change on birds. Nevertheless, surprisingly little research has investigated whether birds are shifting their migratory phenology equally across sex and age classes—a question critical to understanding the potential for trophic mismatch. We used 60 years of bird banding data across North America—comprising over 4 million captures in total—to investigate both spring and fall migratory phenology for a total of 98 bird species across sex and age classes, with the exact numbers of species for each analysis depending on season‐specific data availability. Consistent with protandry, in spring (n = 89 species), adult males were the first to arrive and immature females were the last to arrive. In fall (n = 98), there was little difference between sexes, but adults tended to depart earlier than juveniles. Over 60 years, adult males advanced their phenology the fastest (−0.84 days per decade, 95 CrI = −1.22 to −0.47, n = 36), while adult and immature females advanced at a slower pace, causing the gap in male and female arrival times to widen over time. In the fall, there was no overall trend in phenology by age or sex (n = 57), driven in part by high interspecific variation related to breeding and molt strategies. Our results indicate consistent and predictable age‐ and sex‐based differences in the rates at which species' springtime phenology is shifting. The growing gap between male and female migratory arrival indicates sex‐based plasticity in adaptation to climate change that has strong potential to negatively impact current and future population trends. [ABSTRACT FROM AUTHOR]

The Hawaiian sandburrowers Crystallodytes cookei and Limnichthys nitidus were found to be protandrous hermaphrodites based on a histological examination of gonad morphology and development. The majority of individuals of both species (71% and 75%, respectively) had delimited ovotestes in which ovarian and testicular tissue were divided by a connective tissue barrier. In juveniles and functional males, the ovarian and testicular regions were similar in cross-sectional area, whereas in functional females, the testicular portion was absent or greatly reduced. Reproductive females were significantly larger in body size than functional males but did not differ significantly in size with transitionals (individuals which contained both developing ova and visible spermatozoa). The complete absence of functional females at the smallest size ranges suggests that both species are monogynic; all females are derived from previously mature males. The ovotestis morphology and sequence of gonad development present in C. cookei and L. nitidus are most similar to protandrous porgies (family Sparidae). When compared to sex changing species of the closely related genus Trichonotus (family Trichonotidae), the distinct ovotestis morphology (delimited in creediids vs. mixed in Trichonotus) and differing direction of sex change (protandry vs. protogyny) suggest that sex change evolved independently in these taxa. [ABSTRACT FROM AUTHOR]

Abstract Explosive pollination includes a rapid release of floral sexual elements that are enclosed in modified petals, and a subsequent contact with pollinators’ body. It requires specific groups of visitors in order to assure plant reproduction, thus reproductive success is threatened in species with explosive pollination mechanisms, especially when pollinator activity is uncertain. Autogamy can alleviate such a problem by improving plant reproductive output. Here we investigated the mating strategies of Marsypianthes chamaedrys, a species with an explosive pollen release mechanism and whose medicinal properties are broadly investigated, but no data is available regarding its reproduction. We studied its floral morphology, anthesis, floral visitors and breeding system. Flowers have a bilabiate organization with the reproductive structures housed within a lower, keel-like petal lobe. The species is protandrous and flowers have short life span. Only bees were able to activate the explosive mechanism, while butterflies acted as nectar thieves. Marsypianthes chamaedrys is self-compatible and able to autonomously self-pollinate, likely due to the elongation of the pistil within the keel of unvisited flowers. Marsypianthes chamaedrys likely has a mixed mating system, in which bee pollination and autogamy interplay to improve its reproductive output.

In insects, male mating success and female fecundity usually increase with body size. However, natural selection favors faster maturation, reducing the risk of pre‐reproductive death, when the reproductive season is short in habitats located at high altitudes or far from the equator. Also, if males that mature earlier than females under these conditions increase their mating opportunities, protandry may evolve in their populations. Nonetheless, as body size is strongly correlated with maturation time in insects, faster sexual maturation is reached at the expense of having a small body size. We analyzed the differences in adult body size of males and females of the grasshopper Sphenarium histrio Gerstaecker (Orthoptera: Pyrgomorphidae) in three sites across an altitudinal gradient in southern Mexico. We also evaluated the possibility of protandry in these sampling sites using a common garden experiment. Male and female grasshoppers collected from low altitude sites in the field and reared in the laboratory were larger than those from a high altitude, suggesting genetic differentiation. Grasshoppers from a high altitude hatched earlier, had a shorter development time, presented fewer instars, and were smaller than grasshoppers from the other sampling sites. Moreover, development time in the three sampling sites was shorter in males than in females, suggesting protandry. Interestingly, the males from the three sites showed similar growth rates, but the females from low and high altitudes, respectively, had the fastest and slowest growth rates. In general, the adaptive value of the evolution of protandry has been focused on males. However, it may be that the growth rates of females in these sites could modify the degree of protandry as a response to their risk of pre‐reproductive death and the potential benefits associated with multiple matings. [ABSTRACT FROM AUTHOR]

Life history traits of three commercial and recreational important black seabreams were characterized from the Ryukyu Archipelago of the Northwest Pacific. The active spawning periods were similar among three species and were determined to be between January and March, coinciding with a lower water temperature. The Okinawan yellow-fin seabream Acanthopagrus chinshira is a large-bodied species which exhibits a moderate initial growth, late female maturation, and an estimated intermediate lifespan of 15 years. The Pacific seabream Acanthopagrus pacificus is a medium-bodied species with a slow initial growth and an estimated intermediate lifespan of 20 years. The Okinawa seabream Acanthopagrus sivicolus is a large-bodied species with a rapid initial growth, early maturation, and an estimated intermediate lifespan of 15 years. The present study strongly suggested that all three species of the Okinawan populations showed protandrous hermaphroditism based on the available evidence (size and age frequencies and gonadal histology) and contributed toward the understanding of sexual systems in closely related black seabreams. Detailed age-based demography, which relates directly to productivity and recovery potential, also provided a necessary component for future management and conservation decisions: A. chinshira has a particularly high extinction risk and key approaches for the species preservation are urgently needed. [ABSTRACT FROM AUTHOR]

Although there is abundant evidence that migrant landbirds have modified their migratory timing in response to climate change, few studies have looked for evidence of long-term changes in site use or function, while even fewer studies have looked for differential effects on demographic groups within a species. Here, we analyze 18 years of daily weather data and 17 years of Gray Catbird ( Dumetella carolinensis ) and Common Yellowthroat ( Geothlypis trichas ) capture data to look for evidence of long-term changes in temperature and precipitation as well as arrival timing by species, sex, and age during spring migration in northeastern Pennsylvania, USA. We also determined whether there was evidence of protandry in Gray Catbirds, a sexually monochromatic species. Additionally, we investigated changes in site use, as indicated by long-term change in capture rates or rates of mass gain by age or sex in both species. Although average daily temperatures did not change, we found long-term changes in the amount and probability of precipitation during the spring migratory period (April–May). We also found that both species advanced their arrival timing (Gray Catbirds ~6.6 d/decade, Common Yellowthroats ~2.8 d/decade) and that advances in arrival timing varied by sex or age in both species. We found no evidence of protandry in Gray Catbirds. Further, we found evidence that site functionality changed for both species, as demonstrated by sex-related differences in yearly mass gain for birds using the study site. Understanding the phenological response of migratory species to climate change requires consideration of climate change effects across multiple temporal and geographic scales, and, as our results suggest, consideration of differential effects of climate change by demographic groups within species.

Clownfish can be an excellent research model for investigating the socially-controlled sexual development of sequential hermaphrodite teleosts. However, the molecular cascades underlying the social cues that orchestrate the sexual development process remain poorly understood. Here, we performed a comparative transcriptomic analysis of gonads from females, males, and nonbreeders of Amphiprion clarkii, which constitute a complete social group, allowing us to investigate the molecular regulatory network under social control. Our analysis highlighted that the gonads of nonbreeders and males exhibited high similarities but were far from females, both in global transcriptomic profiles and histological characteristics, and identified numerous candidate genes involved in sexual development, some well-known and some novel. Significant upregulation of cyp19a1a, foxl2, nr5a1a, wnt4a, hsd3b7, and pgr in females provides strong evidence for the importance of steroidogenesis in ovarian development and maintenance, with cyp19a1a playing a central role. Amh and sox8 are two potential key factors that may regulate testicular tissue development in early and late stages, respectively, as they are expressed at higher levels in males than in females, but with slightly different expression timings. Unlike previous descriptions in other fishes, the unique expression pattern of dmrt1 in A. clarkii implied its potential function in both male and female gonads, and we speculated that it might play promoting roles in the early development of both testicular and ovarian tissues. [ABSTRACT FROM AUTHOR]

In hermaphrodites, the allocation of resources to each sex function can influence fitness through mating success. A prediction that arises from sex allocation theory is that in wind‐pollinated plants, male fitness should increase linearly with investment of resources into male function but there have been few empirical tests of this prediction. In a field experiment, we experimentally manipulated allocation to male function in Ambrosia artemisiifolia (common ragweed) and measured mating success in contrasting phenotypes using genetic markers. We investigated the effects of morphological traits and flowering phenology on male siring success, and on the diversity of mates. Our results provide evidence for a linear relation between allocation to male function, mating, and fitness. We find earlier onset of male flowering time increases reproductive success, whereas later flowering increases the probability of mating with diverse individuals. Our study is among the first empirical tests of the prediction of linear male fitness returns in wind‐pollinated plants and emphasizes the importance of a large investment into male function by wind‐pollinated plants and mating consequences of temporal variation in sex allocation. [ABSTRACT FROM AUTHOR]

Protandry is a widespread life‐history phenomenon describing how males precede females at the site or state of reproduction. In migratory birds, protandry has an important influence on individual fitness, the migratory syndrome, and phenological response to climate change. Despite its significance, accurate analyses on the dynamics of protandry using data sets collected at the breeding site, are lacking. Basing our study on records collected during two time periods, 1979 to 1988 and 2006 to 2016, we aim to investigate protandry dynamics over 38 years in a breeding population of willow warblers (Phylloscopus trochilus). Change in the timing of arrival was analyzed in males and females, and protandry (number of days between male and female arrival) was investigated both at population level and within breeding pairs. Our results show advancement in the arrival time at the breeding site in both sexes, but male arrival has advanced to a greater extent, leading to an increase in protandry both at the population level and within breeding pairs. We did not observe any change in sex ratio that could explain the protandry increase, but pronounced temperature change has occurred and been reported in the breeding area and along the migratory route. Typically, natural selection opposes too early arrival in males, but given warmer springs, this counteracting force may be relaxing, enabling an increase in protandry. We discuss whether our results suggest that climate change has induced sex‐specific effects, if these could be evolutionary and whether the timing of important life‐history stages such as arrival at the breeding site may change at different rates in males and females following environmental shifts. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms determining the emergence timing of herbivorous insects is ecologically important. However, little is known about the effect of climatic factors and the presence of conspecific individuals on their emergence in the field. In particular, it is challenging to investigate the seasonal emergence of cicadas because these insects have a long life‐cycle and subterranean larval stages.We assembled a time‐series dataset that consists of daily counts of emerging cicadas together with meteorological factors, using long‐term collection of cicada exuviae by elementary and junior‐high‐school students. We then performed a non‐linear time‐series analysis, empirical dynamic modelling, to identify factors behind the timing of cicada emergence.Our findings are three‐fold: (1) emergence of individuals of the opposite sex constitute a major driver of the number of individuals emerging per day, and this effect is stronger in males than in females, (2) as in other insect species, air temperature consistently affects cicada emergence, but its effects are relatively weak and (3) precipitation and humidity were causally related to emergence.These results are consistent with the theory of sexual selection as well as the fact that it is hard for the subterranean cicada larvae to use information about air temperature. Significantly, the findings are based on long‐term field data collected by non‐expert citizens. [ABSTRACT FROM AUTHOR]

Premise: Morphological and developmental changes as flowers age can impact patterns of mating. At the same time, direct or indirect costs of floral longevity can alter their fitness outcomes. This influence has been less appreciated, particularly with respect to the timing of selfing. We investigated changes in stigma events, autonomous selfing, outcross seed set capacity, and autofertility—a measure representing the potential for reproductive assurance—across floral lifespan in the mixed‐mating biennial Sabatia angularis. Methods: We examined stigma morphology and receptivity, autonomous self‐pollen deposition, and seed number and size under autonomous self‐pollination and hand outcross‐pollination for flowers of different ages, from 1 d of female phase until 14 d. We compared autonomous seed production to maximal outcross seed production at each flower age to calculate an index of autofertility. Results: The stigmatic lobes begin to untwist 1 d post anthesis. They progressively open, sextend, coil, and increase in receptivity, peaking or saturating at 8–11 d, depending on the measure. Autonomous seed production can occur early, but on average remains low until 6 d, when it doubles. In contrast, outcross seed number and size start out high, then decline precipitously. Consequently, autofertility increases steeply across floral lifespan. Conclusions: Changes in stigma morphology and receptivity, timing of autonomous self‐pollen deposition, and floral senescence can interact to influence the relative benefit of autonomous selfing across floral lifespan. Our work highlights the interplay between evolution of floral longevity and the mating system, with implications for the maintenance of mixed mating in S. angularis. [ABSTRACT FROM AUTHOR]

Opisthopappus is a perennial, endemic herb of the Taihang Mountains in China. Two species of this genus (O. longilobus and O. taihangensis) are important wild genetic resources for Asteraceae; however, their reproductive biology has been lacking until now. This study is the first detailed report on the reproductive biology and breeding systems of two Opisthopappus species. Through field observations, the floral syndromes of O. longilobus and O. taihangensis were found to possess a similar pattern, although O. taihangensis has a relatively larger capitulum, more ray ligules, and disc florets. The flowers of both O. longilobus and O. taihangensis are protandrous, a character that can prevent autogamy at the single-flower level, and insects are required for pollination. Further, brightly ligules, brightly bisexual florets, unique fragrance, and amount of nectar suggest that these species propagate via an entomophilous pollination system. Hymenopteran and Diptera species were observed as the effective pollinators for these two species. The outcrossing index, pollen/ovule ratio and the results of hand pollination indicated that these Opisthopappus species might have a mixed mating system that combines cross-fertilization and partial self-fertilization for O. longilobus and O. taihangensis, outcrossing predominated in the breeding system, while self-pollination played an important role in seed production when insect pollination was unavailable, particularly in a harsh environment, such as the Taihang Mountains cliffs. Meanwhile, O. taihangensis might better adapt to severe surroundings with relatively complex floral syndromes, specifically through the attraction of visiting insects and a high seed set rate. The above results not only provide reference information toward a better understanding of the survival strategies of O. longilobus and O. taihangensis in the Taihang Mountains but also lay a solid foundation for further exploring the molecular mechanisms that underly their adaptation under cliff environments.

Information on reproductive biology and pollination ecology studies of threatened plants are essential to develop strategies for their sustainable utilization and effective conservation. As such, these studies were conducted on Rheum webbianum, a high-value “vulnerable” medicinal herb of the north-western Himalaya. This species presents a unique mode of reproductive behavior through the involvement of different floral events, including the movement of reproductive organs. The plants survive extremely cold conditions through underground perennating rhizomes that sprout into juvenile shoots with the onset of the favorable climatic conditions. The peduncle arises from the axils of the radical leaves, bearing a globular collection of densely arranged hermaphrodite flowers with temporally separated male and female phases; the male phase precedes the female phase (protandry). Anther dehiscence and stigma receptivity is post-anthesis. Anthers dehisce longitudinally along margins, liberating a large mass of spherical and tricolpate pollen with spinulose exine. Pollen viability decreased to < 10% on day 9. Pistil is tristylous, with each style terminating into a fan-shaped stigma lobe. The pollen receptive surface of each stigmatic lobe remains incurved at an angle of 360° and shows upward movement after anthesis, forming a funnel-like structure at an angle of 180° with respect to the ovary. Pollination syndrome is ambophilous. Spontaneous autogamy or geitonogamy to a certain extent is achieved in this species due to the arrangement of flowers in the inflorescence and overlapping of male and female reproductive phases among them. Incurved stigmatic lobes and outward movement of stamens too facilitate outcrossing. Pollen/ovule ratio estimates, results of pollination experiments on breeding behavior, outcrossing, and self-compatibility indices demonstrated that plants are self-compatible and cross-fertile.

Thatched roofs are artificial environments that serve as nesting sites for a variety of insects, including tube‐nesting wasps, but they have been declining drastically in recent years. In this study, we investigated the nesting habits of a eumenine wasp, Symmorphus apiciornatus, nesting in a group at thatched roofs in a northern part of Ibaraki Prefecture, central Japan. Genetic diversity and genetic structure in the area were also investigated. Sex ratios at most study sites were not biased. Males emerged first and waited for females to mate around the natal nests, suggesting a high possibility of breeding between the wasps having emerged at a given thatched roof under the recent situation where there has been a drastic reduction in the number of houses with a thatched roof. Nevertheless, the genetic diversity in a given local population or a thatched roof was relatively high and significant genetic differentiation among thatched roofs was not detected. [ABSTRACT FROM AUTHOR]

Information on reproductive biology and pollination ecology studies of threatened plants are essential to develop strategies for their sustainable utilization and effective conservation. As such, these studies were conducted on Rheum webbianum , a high-value "vulnerable" medicinal herb of the north-western Himalaya. This species presents a unique mode of reproductive behavior through the involvement of different floral events, including the movement of reproductive organs. The plants survive extremely cold conditions through underground perennating rhizomes that sprout into juvenile shoots with the onset of the favorable climatic conditions. The peduncle arises from the axils of the radical leaves, bearing a globular collection of densely arranged hermaphrodite flowers with temporally separated male and female phases; the male phase precedes the female phase (protandry). Anther dehiscence and stigma receptivity is post-anthesis. Anthers dehisce longitudinally along margins, liberating a large mass of spherical and tricolpate pollen with spinulose exine. Pollen viability decreased to < 10% on day 9. Pistil is tristylous, with each style terminating into a fan-shaped stigma lobe. The pollen receptive surface of each stigmatic lobe remains incurved at an angle of 360° and shows upward movement after anthesis, forming a funnel-like structure at an angle of 180° with respect to the ovary. Pollination syndrome is ambophilous. Spontaneous autogamy or geitonogamy to a certain extent is achieved in this species due to the arrangement of flowers in the inflorescence and overlapping of male and female reproductive phases among them. Incurved stigmatic lobes and outward movement of stamens too facilitate outcrossing. Pollen/ovule ratio estimates, results of pollination experiments on breeding behavior, outcrossing, and self-compatibility indices demonstrated that plants are self-compatible and cross-fertile. [ABSTRACT FROM AUTHOR]

Introduction: The bivalve Anadara tuberculosa is an important fishery in the Eastern Tropical Pacific. The sex ratio varies along its geographic range and there are cases of hermaphroditism, occasional in some populations, normal in others. These characteristics may be a response to anthropogenic and environmental pressure. Objective: To evaluate sex ratio and hermaphroditism of the species in the Panamanian Pacific. Methods: Data on reproductive features of A. tuberculosa generated between 1994 and 2020 for Gulf of Montijo, as well as 2017 data from mangroves of David was analyzed. Macroscopic diagnosis of individual sex is sensitive to the problem of indeterminate individuals, which in turn can skew the sex ratio analysis; therefore, the macroscopic method was compared with histological sections to generate a correction factor to adjust the macroscopically determined sex ratio. Results: For Montijo, histology indicated that the female to male sex ratio ranged from 1:1 to 3.2:1 between 1994 and 2017, while macroscopy indicated 1.9:1 to 5.1:1 between 2004 and 2020. For David, histology indicated a ratio of 3.7:1, and macroscopy 7.9:1. At both localities, larger specimens had more sex ratio variation, independently of the technique, and there was non-casual protandric hermaphroditism in 2017. Conclusion: The occurrence of protandric hermaphroditism and sex ratio changes suggest anthropogenic and environmental pressure in all populations. [ABSTRACT FROM AUTHOR]

Insect pollination services play a major role in onion, Allium cepa L. due to the prevalence of protandry. A study was conducted at the experimental fields of ICAR - Indian Institute of Horticultural Research, Bengaluru, Karnataka, India (13.13 oN; 77.49 oE) to understand the foraging behaviour of major insect pollinators associated with onion crop (cv. Arka Kalyan). Continuous surveillance revealed that onion took 70 - 75 days for flower bud initiation and 90 - 95 days for maximum flower opening. A single bulb produced 4.00 ± 1.05 flowering stalks which produced umbel inflorescence that consisted of numerous individual flowers called florets. The mean number of florets in an umbel (449.30 ± 29.47) and the duration of each floret (5.60 ± 0.52 days) were worked out. In general, each floret produced 6.00 -7.00 anthers (Mean ± SE: 6.10 ± 0.32) with a mean number of 1581 pollen grains per anther. A total of 1735 and 1852 individual pollinators were observed visiting the onion during 2020 and 2021, respectively. The floral visitor's data from transect sampling revealed their abundance as: Apis florea > Trigona iridipennis > Apis dorsata > Apis cerana > Ischiodon scutellaris > Eristalis obliquus for two consecutive years. Of all floral visitors, A. florea had recorded highest visits (26.92 %), while Eristalis obliquus recorded the least foraging visits (7.38 %). The observations on foraging behaviour revealed that major foraging activity was carried out by A. cerana, as it spent maximum amount of time on inflorescence (3.30 ± 0.82 umbel / min) followed by A. dorsata (2.50 ± 0.71 umbel / min) and the least with T. iridipennis (1.40 ± 0.52 umbel / min). However, time spent / umbel was maximum with T. iridipennis (45.80 ± 4.41 sec / umbel) and the least was found with A. cerana (16.10 ± 1.85 sec / umbel). [ABSTRACT FROM AUTHOR]

The influence of the social environment on the timing of the annual cycle is poorly understood. Seasonally migratory birds are under pressure to accurately time their spring migration, and throughout the annual cycle, they may experience variability of the local sex-ratio. A population-level male-biased sex ratio is predicted to advance spring migration timing in males and is attributed to the increased intra-specific competition for access to females and/or breeding territories. The present study had two goals. First, to develop a method that utilizes digitally coded radio-transmitters to quantify the activity of flocked individuals in captivity. Second, to use this method to test the hypothesis that the social environment influences the spring migration traits of male yellow-rumped warblers (Setophaga coronata coronata). To accomplish this, birds were captured in the fall in Long Point, Ontario, and transferred to the Advanced Facility for Avian Research, London, Ontario. In the winter, they were assigned to a slightly male- or female-biased treatment and housed in flocks in large free-flight rooms. Throughout the experimental period, we took body mass measurements and standardized photos to monitor body condition and molt progression. To measure locomotor activity, the birds were outfitted with digitally coded radio-transmitters in April and photo-triggered to enter a migratory phenotype. The tagged birds were released at their capture site in May and the Motus Wildlife Tracking System was used to determine stopover departure timing and migratory movements. Sex ratio did not influence body mass or molt progression. However, males from the male-biased treatment had significantly less locomotor movement than those from the female-biased treatment. Additionally, a lower proportion of males from the male-biased treatment initiated migratory restlessness, an indicator of the urge to migrate. Overall, these findings suggest that the social environment can influence behavior of songbirds, but do not support the hypothesis that a male-biased sex ratio accelerates migration.

Hermaphrodite systems offer unique opportunities to study sexual differentiation, due to their high degree of sexual plasticity and to the fact that, unlike gonochoristic systems, the process is not confined to an early developmental stage. In protandric shrimp species, such as Hippolyte inermis and Pandalus platyceros, male differentiation is followed by transformation to femaleness during adulthood. The mechanisms controlling sexual differentiation have not been fully elucidated in crustaceans, but a key role has been attributed to the insulin-like hormone (IAG) produced by the androgenic gland (AG), a crustacean masculine endocrine organ. To uncover further transcriptomic toolkit elements affecting the sexual differentiation of H. inermis, we constructed eye and whole body RNA libraries of four representative stages during its protandric life cycle (immature, male, young female and mature female). The body libraries contained transcripts related to the reproductive system, among others, while the eye libraries contained transcripts related to the X-organ-sinus gland, a central endocrine complex that regulates crustacean reproduction. Binary pattern analysis, performed to mine for genes expressed differentially between the different life stages, yielded 19,605 and 6,175 transcripts with a specific expression pattern in the eye and body, respectively. Prominent sexually biased transcriptomic patterns were recorded for the IAG and vitellogenin genes, representing, respectively, a key factor within the masculine IAG-switch, and a precursor of the yolk protein, typical of feminine reproductive states. These patterns enabled the discovery of novel putative protein-coding transcripts exhibiting sexually biased expression in the H. inermis body and eye transcriptomes of males and females. Homologs to the above novel genes have been found in other decapod crustaceans, and a comparative study, using previously constructed transcriptomic libraries of another protandric shrimp, P. platyceros, showed similar sexually biased results, supporting the notion that such genes, mined from the H. inermis transcriptome, may be universal factors related to reproduction and sexual differentiation and their control in other crustaceans. This study thus demonstrates the potential of transcriptomic studies in protandric species to uncover unexplored layers of the complex crustacean sex-differentiation puzzle.

Conspecific females and males often follow different development trajectories which leads to sex differences in age at maturity (sexual bimaturism, SBM). Whether SBM is typically selected for per se (direct selection hypothesis) or merely represents a side‐effect of other sex‐related adaptations (indirect selection hypothesis) is, however, still an open question. Substantial interspecific variation in the direction and degree of SBM, both in invertebrates and vertebrates, calls for multi‐species studies to understand the relative importance of its evolutionary drivers. Here we use two complementary approaches to evaluate the evolutionary basis of SBM in insects. For this purpose, we assembled an extensive literature‐derived data set of sex‐specific development times and body sizes for a taxonomically and ecologically wide range of species. We use these data in a meta‐analytic framework to evaluate support for the direct and indirect selection hypotheses. Our results confirm that protandry – males emerging as adults before females – is the prevailing form of SBM in insects. Nevertheless, protandry is not as ubiquitous as often presumed: females emerged before males (= protogyny) in about 36% of the 192 species for which we had data. Moreover, in a considerable proportion of species, the sex difference in the timing of adult emergence was negligible. In search for the evolutionary basis of SBM, we found stronger support for the hypothesis that explains SBM by indirect selection. First, across species, the direction and degree of SBM appeared to be positively associated with the direction and degree of sexual size dimorphism (SSD). This is consistent with the view that SBM is a correlative by‐product of evolution towards sexually dimorphic body sizes. Second, within protandrous species, the degree of protandry typically increased with plastic increase in development time, with females prolonging their development more than males in unfavourable conditions. This pattern is in conflict with the direct selection hypothesis, which predicts the degree of protandry to be insensitive to the quality of the juvenile environment. These converging lines of evidence support the idea that, in insects, SBM is generally a by‐product of SSD rather than a result of selection on the two sexes to mature at different times. It appears plausible that selective pressures on maturation time per se generally cannot compete with viability‐ and fecundity‐mediated selection on insect body sizes. Nevertheless, exceptions certainly exist: there are undeniable cases of SBM where this trait has evolved in response to direct selection. In such cases, either the advantage of sex difference in maturation time must have been particularly large, or fitness effects of body size have been unusually weak. [ABSTRACT FROM AUTHOR]

The aim of this study was to confirm the type of protandry adopted by M. rhizophorae and to describe the size at which sex change occurs in order to test predictions of sex allocation theory. The reproductive output also was investigated, based on fecundity and embryo volume. Specimens were collected cohabiting burrows built by mud shrimps Upogebia omissa in an estuary region in the northeast of Brazil. The body size (carapace length, CL) and sex of the shrimps were recorded. Observations were made developmental stages of the embryos, fecundity, and embryo volume. A total of 204 M. rhizophorae individuals was sampled, of which 170 (83.3%) male phase (MP) and 34 (16.7%) female phase (FP) individuals. The body size (mean ± SD) of the individuals in the MP was smaller than in the FP: 3.91 ± 0.78 and 6.18 ± 0.52 mm CL, respectively. The size at which 50% of the shrimps changed to FP (CL50) was 5.62 ± 0.01 mm CL. Reproductive output (fecundity and embryo volume) increased linearly with shrimp body size. An increase in embryo size during development and the loss of embryos during final stage of development were recorded. In this study, the behaviour exhibited by M. rhizophorae (share a burrow with another shrimp species) was recorded for the first time, expanding knowledge about the ecology of this semi-terrestrial shrimp. Our results indicate the adoption of strict protandric hermaphroditism by M. rhizophorae. Our study supports the prediction of sex allocation theory that sex ratio is significantly biased towards the first-sex in sequential hermaphrodites. We also found evidence of possible trade-offs between the size in which the sex change occurs and the reproductive strategy exhibited by M. rhizophorae. [ABSTRACT FROM AUTHOR]

In this study we investigated sex change and the mating system of a platycephalid fish, Platycephalus sp. 2 (Japanese name: Magochi), found in Japanese waters. Among 202 specimens from Tateyama, Chiba, Japan, obtained in 2014 and 2015, histological observation of the gonads distinguished 103 females, 97 males and two hermaphrodites (individual with both ovarian and testicular parts). Females were significantly larger than males. In a rearing experiment conducted with six males and three females, only the smallest male changed sex to female, thereby revealing protandry in this species. In field observations, seven males and eight females appeared throughout the study period. During pairing, a male would follow a female on the sandy bottom. The mating system of this species has been regarded as random mating based on temporal pair bonding, no territoriality, and no size-assortative mating, which correspond well with the size-advantage model. In a previous study Platycephalus sp. 2 was regarded as a gonochore, with a higher growth rate for females than males. Thus, females should be larger than males. In the present study, there was no significant difference in age between the sexes, as estimated from the number of opaque zones in sagitta otoliths. Overall, these findings indicate that there are primary females and males without sex change. Thus, protandrous and gonochoristic individuals may co-exist in populations of Platycephalus sp. 2. [ABSTRACT FROM AUTHOR]

Differential migration strategies in the same population provide an opportunity to investigate the development and constraints of the migratory programme. We used data from birds ringed from the large Danish breeding population of Great Cormorants, Phalacrocorax carbo sinensis, to investigate age- and sex-specific differences in migratory patterns, which may inform our understanding of the ontogeny of partial migration schedules or protandric advantages of males arriving at breeding grounds in advance of females. We tested spatial and temporal variation in migration strategy from migration distance, orientation and by region. We observed clear partial migration strategies in the combined data, and by group, following post-breeding dispersal. We found differential migration patterns by age, with migratory adults departing earlier than birds on their first migration. There was a tendency for a greater concentration of adults utilising sites in central Europe, while a higher than expected proportion of young birds occupied the periphery of the wintering range. Re-encounters of birds of known sex during autumn and winter indicated that males remained closer to the breeding site than females, with sex-specific regional segregation. While our results did not support the migration pattern of young birds being governed by an innate control of both direction and distance, it may be explained in part by intra-specific competition driving the resultant non-breeding distribution. This social dynamic may be extended to the differential migration patterns between the sexes. Furthermore, the sex-specific wintering distributions may explain the development of protandry within the partial migration system. [ABSTRACT FROM AUTHOR]

Birds of different ages or sexes may select different migration strategies. We studied the spring and autumn migration as well as the body condition of different ages and sexes of the Blue-and-white Flycatcher Cyanoptila cyanomelana at a migration corridor in Yancheng, Jiangsu, China, in 2017. A total of 121 individuals were captured in mist nets, 62 in spring and 59 in autumn. We found that adult males were caught significantly earlier than females in both seasons (Mann-Whitney U test, spring, P = 0.012; autumn, P=0.019), but the migration timing of immature birds was much the same as adults of the same sex in both seasons (Mann-Whitney U test, spring, P=0.571; autumn, P=0.236). Body size and sex were found to affect body mass significantly (ANCOVA, wing length P =0.001; sex P=0.001). No individuals were recaptured in both migration seasons, hence the Blue-and-white Flycatcher may adopt a strategy of one-day stopovers. The Yancheng seawall forest may represent a low-quality habitat for this species, and birds pass this location quickly in search of other suitable habitats. [ABSTRACT FROM AUTHOR]