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Wing dimorphism is a distinguishing characteristic of brown planthopper Nilaparvata lugens (Stål) populations, wherein adults exhibit 2 distinct morphs: long-winged and short-winged. The presence of long-winged individuals often heralds the onset of migration, while short-winged morphs signify high reproduction and can be associated with population outbreaks. This phenomenon underscores the adaptability of these insects in response to environmental cues and their impact on agricultural ecosystems. Wing morphs of N. lugens are controlled by genetical and environmental factors. Mate choice between long and short-winged adults affects wing morphs of offspring. In this study, we found that the wild population had no persistent preference for choosing long-winged or short-winged adults to mate. But in 2 multigenerational selected lineages for long and short-winged morphs, the short-winged males preferred to short-winged females to mate and the long-winged males had no preference. In the nearly pure-bred lineages of long-winged and short-winged morphs, both wing morphs of females preferred for short-winged males. Purification of wing morph lineages enhanced mating preference for short-winged partners. When the wing developmental gene InR1 or InR2 was interfered by RNAi, the pure-bred lineage of long-winged morph mainly produced short-winged adults and the short-winged morphs produced long-winged adults, and these adults exhibited preference to mate with short-winged partners. The tendency to mate with short-winged morphs leads to more short-winged offspring which easily causes the rapid growth of populations. [ABSTRACT FROM AUTHOR]

Consistent behavioural responses of individuals (i.e. personality) have been linked with reproductive output and success across a range of taxa. In species with biparental care, the behavioural compatibility of breeding partners may also affect reproductive output, perhaps because it allows greater pair coordination during breeding attempts. The aim of this study was to investigate whether pairs of greylag geese are assortatively paired for personality, and whether these traits within pairs affect reproductive output. We used repeated behavioural assays in the field to quantify three personality traits: activity (focal observations), boldness (flight initiation distance) and aggressiveness (response to mirror image). We assessed their correlation with three measures of reproductive output (clutch size, hatching success and fledging success). All three personality traits were significantly repeatable; however, we found no evidence that pairs within the flock routinely assortatively paired for any trait, regardless of the pair bond duration. Nevertheless, there may still be fitness benefits associated with pair compatibility. Pairs in which the partners were similar in average boldness had higher hatching success, although this trend was not found for clutch size or fledging success. These results suggest that the benefits of having similar predator defence strategies within pairs differ across the breeding cycle, resulting in no overall selection for assortative mating for boldness. • Personality of both parents and their similarity in personality can affect fitness. • Greylag geese were not assortatively paired for personality at the flock level. • Similarity in parental personality correlated with hatching success. • Similarity in personality within pairs did not affect fledging success. [ABSTRACT FROM AUTHOR]

How colour polymorphisms are maintained in natural populations constitutes a key subject of study for evolutionary ecologists. One of the mechanisms that has been put forward to explain this phenomenon is negative frequency-dependent selection, which can be caused by different mechanisms. Among these mechanisms is mate choice, or the selection as a potential mate of the rare or dissimilar colour morph by the choosy sex of a given species. In the context of colour polymorphism, mate choice predicts the occurrence of a negative assortative mating pattern, whereby different colour morphs mate more often than expected by chance alone. However, negative assortative mating can also result from other mechanisms, making it, at best, a fallible indicator of a mate choice-driven negative frequency-dependent selection. For this reason, experimental evidence explicitly connecting such a mating pattern to mate choice is necessary to claim that a particular colour polymorphism is being maintained by negative frequency-dependent selection. Here we present experimental evidence backing this relationship for the colour polymorphic marine gastropod Littorina saxatilis from the Ría de Vigo (NW Iberian Peninsula), although how specifically these organisms choose their mates remains unclear. This calls for further experimental efforts to clarify this issue and its relationship to the maintenance of colour polymorphism in L. saxatilis. [ABSTRACT FROM AUTHOR]

Traits under divergent ecological selection that also function during mating can be important in maintaining species boundaries. Few studies have considered mutual mate choice, where both males and females base mating decisions on the same trait. Wing colouration in Heliconius butterflies evolved as a warning signal but also functions as a mating cue. We investigated the contribution of visual preference to assortative mating in an aposematic butterfly Heliconius cydno in the context of reproductive isolation with its sympatric, visually distinct relative Heliconius melpomene. Heliconius cydno have conspicuous white bands on their forewings, whereas those of H. melpomene are red in colour. We predicted that both sexes of H. cydno contributed to assortative mating by exhibiting visual preference towards conspecific wing colouration. We analysed published and new data from preference experiments, in which males were presented with conspecific and H. melpomene females. We also recorded female responses and mating outcomes in choice experiments, involving conspecific males with either the original white or artificially painted red forewing bands. Both sexes of H. cydno responded more positively towards the conspecific colouration, and males strongly preferred females of its own colours. In contrast, male colouration did not predict mating outcomes in female choice experiments. As courtships are initiated by males in butterflies, our findings suggest that female visual preference might be of secondary importance in H. cydno. Our data also suggest that the contribution of visual preference to reproductive isolation might be unequal between H. cydno and its sympatric relative H. melpomene. [ABSTRACT FROM AUTHOR]

In birds, sexual selection on plumage may promote sexual dichromatism and male ornamentation. However, even in drab species without obvious sexual dichromatism, plumage may still be used for mate choice. A previous study found weak but significant sexual size dimorphism in North American Black Terns (Chlidonias niger surinamensis), but no assortative mating based on morphology. However, the relevance of plumage variation to mate choice in this species is yet untested. Here, using reflectance spectrometry and avian visual modeling, we revealed that Black Tern males and females exhibited a subtle but significant difference in brightness (males darker) in a midwestern USA population. Importantly, the achromatic contrast between the sexes was perceptible during mate choice. Moreover, there was evidence of disassortative mating for plumage color as measured by hue and saturation, but not brightness. There was no relationship between plumage color or brightness and body mass. This finding suggests that visual signals unrelated to body condition may be relevant to Black Tern mate choice. The pattern of disassortative mating was unexpected, and potential benefits of choosing a mate dissimilar from oneself are discussed. This study highlights the importance of considering the avian visual system when studying plumage variation elusive to human observers. [ABSTRACT FROM AUTHOR]

Hybridization and subsequent genetic introgression are now known to be common features of the histories of many species, including our own. Following hybridization, selection often purges introgressed DNA genome-wide. While assortative mating can limit hybridization in the first place, it is also known to play an important role in postzygotic selection against hybrids and, thus, the purging of introgressed DNA. However, this role is usually thought of as a direct one: a tendency for mates to be conspecific reduces the sexual fitness of hybrids, reducing the transmission of introgressed ancestry. Here, we explore a second, indirect role of assortative mating as a postzygotic barrier to gene flow. Under assortative mating, parents covary in their ancestry, causing ancestry to be "bundled" in their offspring and later generations. This bundling effect increases ancestry variance in the population, enhancing the efficiency with which postzygotic selection purges introgressed DNA. Using whole-genome simulations, we show that the bundling effect can comprise a substantial portion of mate choice's overall effect as a postzygotic barrier to gene flow. We then derive a simple method for estimating the impact of the bundling effect from standard metrics of assortative mating. Applying this method to data from a diverse set of hybrid zones, we find that the bundling effect increases the purging of introgressed DNA by between 1.2-fold (in a baboon system with weak assortative mating) and 14-fold (in a swordtail system with strong assortative mating). Thus, assortative mating's bundling effect contributes substantially to the genetic isolation of species.

Work on the Lake Victoria cichlids Pundamilia nyererei (red dorsum males, deeper water), Pundamilia pundamilia (blue males, shallower water) and related species pairs has provided insights into processes of speciation. Here, we investigate the female mating behaviour of 5 Pundamilia species and 4 of their F1 hybrids through mate choice trials and paternity testing. Complete assortative mating was observed among all sympatric species. Parapatric species with similar depth habitat distributions interbred whereas other parapatric and allopatric species showed complete assortative mating. F1 hybrids mated exclusively with species accepted by females of the parental species. The existence of complete assortative mating among some currently allopatric species suggests that pre-existing mating barriers could be sufficient to explain current patterns of co-existence, although, of course, many other factors may be involved. Regardless of the mechanism, mating preferences may influence species distribution in potentially hybridizing taxa, such as in the adaptive radiation of cichlid fish. We suggest that this at least partly explains why some species fail to establish breeding populations in locations where they are occasionally recorded. Our results support the notion that the mating preferences of potentially cross-breeding species ought to be included in coexistence theory. [ABSTRACT FROM AUTHOR]

While numerous theoretical population genetic models predict that mating assortatively by genetic "quality" will enhance the efficiency of purging of deleterious mutations and/or the spread of beneficial alleles in the gene pool, empirical examples of assortative mating by quality are surprisingly rare and often inconclusive. Here, we set out to examine whether fruit flies (Drosophila melanogaster) engage in assortative mating by body-size phenotype, a composite trait strongly associated with both reproductive success and survival and is considered a reliable indicator of natural genetic quality. Male and female flies of different body-size classes (large and small) were obtained under typical culture conditions, which allows us to use standing variation of body size without involving artificial nutritional manipulation, so that their interactions and mating patterns could be measured. While flies did not exhibit assortative courtship behavior, when patterns of offspring production were analyzed, it was found that individuals produced more offspring with partners of similar quality/body size, resulting produced from disassortative mating. Together, these results validate theoretical predictions that sexual selection can enhance the effects of natural selection and consequently the rate of adaptive evolution in a positive correlation in fitness between mates. Subsequent assays of offspring fitness indicated that assortative mating produced sons and daughters that had greater or equal reproductive success than those [ABSTRACT FROM AUTHOR]

In long‐lived monogamous species, the trigger of costly re‐pairing is not always clear. Limited research suggests that within‐pair behavioural compatibility may be an important driver of partnership success, as cooperation should be enhanced when pair members' decisions complement one another. Animals' decision‐making processes are influenced by personality traits – defined as individual differences in behaviour that are stable in time. Despite the potential for the personality trait 'boldness' to (a) directly impact individual willingness to re‐pair and (b) indirectly impact re‐pairing choices via reproductive success, there is currently little work exploring how re‐pairing decisions might be impacted by the pair members' personalities. Using a 13‐year dataset, we investigated whether within‐pair boldness and its relationship with breeding success explained re‐pairing patterns of black‐legged kittiwakes (Rissa tridactyla), breeding in two Arctic colonies. We found that pairs with dissimilar boldness levels were more likely to experience breeding failure and that failed pairs were more likely to re‐pair the following year. Despite this, only one colony displayed evidence of assortative mating by boldness, and there was no indication that re‐pairing impacted reproductive success the following season. Neither individual nor pair boldness directly influenced re‐pairing probability; however, in both colonies, re‐pairing birds chose partners that were slightly more similar to themselves in boldness than their previous mates. These results imply an indirect pathway by which poorer behavioural compatibility within pairs may lead to breeding failure and ultimately re‐pairing. Our findings highlight the importance of behavioural compatibility, and possibly personality, in mitigating sexual conflict and its population‐specific drivers. [ABSTRACT FROM AUTHOR]

Assortative mating, where individuals non‐randomly mate with respect to phenotype or genotype, can occur when preferences between potential mates have evolved. When such mate preferences occur in a population it can drive evolutionary and phenotypic divergence. But the extent to which assortative mating, mate preference, and development are evolutionarily linked remains unclear. Here we use Streblospio benedicti, a marine annelid with a rare developmental dimorphism, to investigate if mate‐choice could contribute to developmental evolution. For S. benedicti two types of ecologically and phenotypically similar adults persist in natural populations, but they give rise to distinctly different offspring with alternative life‐histories. This dimorphism persists despite the absence of post‐zygotic reproductive barriers, where crosses between the developmental types can produce phenotypically intermediate offspring. How this life‐history strategy evolved remains unknown, but assortative mating is a typical first step in evolutionary divergence. Here we investigate if female mate‐choice is occurring in this species. We find that mate preferences could be contributing to the maintenance of alternative developmental and life‐history strategies. Research highlights: It is rare to find an organism that has two types of development within a species. We use such a system to investigate if mate preference between the developmental types is a possible mechanism to create or reinforce population diversification. [ABSTRACT FROM AUTHOR]

Evidence from human and nonhuman primates suggests that females avoid breeding with close kin and may choose mates based on MHC diversity, which can improve offspring survival. In despotic societies, female mate choice may be hindered by male sexual coercion, but in egalitarian societies, females may be less constrained. Among northern muriquis—an egalitarian, polygynandrous primate with male philopatry—analyses of new data on paternity and variation at microsatellite and MHC loci, combined with behavioural and life-history data, revealed that sires showed higher MHC diversity than expected by chance and were never close kin of dams, consistent with predictions of female mate choice and close inbreeding avoidance. However, females did not differentially reproduce with males who were more distantly related to them or more dissimilar at the MHC than expected by chance, nor with those who had more MHC alleles distinct from their own. The lack of male dominance may permit females to identify and reproduce preferentially with non-offspring males and with males who are more diverse at the MHC. Nonetheless, the absence of disassortative mating at the MHC and neutral loci suggests that female mate choice may be limited by other factors impacting male fertilization success. [ABSTRACT FROM AUTHOR]

Mate choice is a key process in animals to optimize the fitness benefits of reproduction, and it is generally guided by phenotypic features of potential partners that mirror reproductive abilities. Assortative mating occurs when there is within-pair selection for specific functional traits that can confer fitness benefits. Assortative mating can be positive if mates are more similar, and negative if they are more dissimilar than expected by chance. Mate choice is particularly important in long-lived species with biparental care, such as procellariforms that form long term monogamous bonds. We assessed the mating strategy of a sexually dimorphic Mediterranean procellariform, the Scopoli's Shearwater (Calonectris diomedea), by testing for assortative mating according to bill (in accordance with previous studies on a sister species) and tarsus size (proxy of body size). We found that shearwaters adopted a positive size-assortative mating by tarsus length, while mating for bill size was random. Moreover, tarsus length was positively correlated with the duration of incubation shifts, when individuals are fasting on eggs. The observed assortative mating could be the results of choice by similarity between individuals, likely because partners with similar relative size have similar tolerance to fasting. Alternatively, the observed pattern could be the product of mutual mate choice, with a selection for large size that could confer competitive abilities in nest selection, defense, foraging aggregations and fasting ability. While our data suggest strong assortative mating in the Scopoli's Shearwater (R = 0.4), we cannot fully disentangle the multiple processes at play acting on mate choice. [ABSTRACT FROM AUTHOR]

Cooperative species have provided extensive evidence on the evolution of cooperation and kin selection mechanisms, but they have been poorly studied in terms of sexual selection. Assortative mating has been recorded in several taxonomic groups and has significant implications for population genetics. In this study, we investigated the occurrence of sex differences, assortative mating, and the relationship between ornaments and fitness in the campo flicker (Colaptes campestris campestris). Campo flickers are facultative cooperative breeders with a complex social and reproductive system. Both males and females are ornamented in the species. Our results demonstrate that males and females are almost entirely alike, and that they mate assortatively for neck and throat coloration. Moreover, individuals possessing larger crowns and a lighter yellow neck coloration were more likely to reproduce. Surprisingly, more homozygous individuals were also more likely to reproduce. Our results support at least two possibilities. The first possibility is that same-sex competition within and between social units may be intense and likely to influence territory occupation, within-group hierarchy, and, ultimately, reproductive success. Alternatively, variation in reproductive success may be associated with mutual sex preferences. The association between fitness and lower heterozygosity may be related to some level of inbreeding, although it does not seem to be impacting campo flicker population numbers. Significance statement: In this study, we investigated the extent to which morphometric traits and plumage coloration predict sex, body condition, and breeding probability in the facultative cooperative breeder Campo Flicker (Colaptes campestris campestris). Our results showed that only body mass differed significantly between males and females, with males being heavier. Males and females are almost entirely alike in terms of coloration. Interestingly, we found that larger crowns and a lighter yellow neck coloration were positively associated with breeding probability, while heterozygosity was negatively associated. These findings advance our understanding of the role of sexual selection in cooperative breeders and provide valuable insights into the impact of competition and mate preferences in ornament evolution and population genetics of social species. [ABSTRACT FROM AUTHOR]

Research Highlight: Woodman, J. P., Cole, E. F., Firth, J. A., Perrins, C. M., & Sheldon, B. C. (2022). Disentangling the causes of age‐assortative mating in bird populations with contrasting life‐history strategies. Journal of Animal Ecology, https://doi.org/10.1111/1365‐2656.13851. In their study of age‐assortative mating, Woodman and colleagues thoroughly and concisely detail its behavioural determinants using datasets, astonishing in themselves, amassed from their decades‐long studies of mute swans (Cygnus olor) and great tits (Parus major), species that are respectively longer‐ and shorter‐lived and occupying different segments of the slow/fast life‐history continuum. Here, they show that positive age‐assortative mating occurs through active, age‐based mate selection in mute swans which play the long game, whereas in the shorter‐lived great tit this is principally a passive byproduct of demographic processes. That great tits have relatively lower interannual survivorship means that newly recruited, young birds occupy a larger proportion of the breeding population in any given year than occurs in mute swans. The adaptive significance of age‐assortative mating is yet to be determined, but the current study provides an exciting possibility for the role of selection on assortative mating generally in either promoting or constraining active mate selection and sexual dimorphism within and across the tree of life. [ABSTRACT FROM AUTHOR]

Age shapes fundamental processes related to behaviour, survival and reproduction, where age influences reproductive success, non‐random mating with respect to age can magnify or mitigate such effects. Consequently, the correlation in partners' age across a population may influence its productivity. Despite widespread evidence for age‐assortative mating, little is known about what drives this assortment and its variation. Specifically, the relative importance of active (same‐age mate preference) and passive processes (assortment as a consequence of other spatial or temporal effects) in driving age assortment is not well understood.In this paper, we compare breeding data from a great tit and mute swan population (51‐ and 31‐year datasets, respectively) to tease apart the contributions of pair retention, cohort age structure and active age‐related mate selection to age assortment in species with contrasting life histories.Both species show age‐assortative mating and variable assortment between years. However, we demonstrate that the drivers of age assortment differ between the species, as expected from their life histories and resultant demographic differences. In great tits, pair fidelity has a weak effect on age‐assortative mating through pair retention; variation in age assortment is primarily driven by fluctuations in age structure from variable juvenile recruitment. Age‐assortative mating is, therefore, largely passive, with no evidence consistent with active age‐related mate selection. In mute swans, age assortment is partly explained by pair retention, but not population age structure, and evidence exists for active age‐assortative pairing.This difference is likely to result from shorter life‐spans in great tits compared with mute swans, leading to fundamental differences in their population age structure, whereby a larger proportion of great tit populations consist of a single age cohort. In mute swans, age‐assortative pairing through mate selection may also be driven by greater age‐dependent variation in fitness.The study highlights the importance of considering how different life histories and demographic differences arising from these affect population processes that appear congruent across species. We suggest that future research should focus on uncovering the proximate mechanisms that lead to variation in active age‐assortative mate selection (as seen in mute swans); and the consequences of variation in age structure on the ecological and social functioning of wild populations. [ABSTRACT FROM AUTHOR]

Genetic correlation between mates at specific loci can greatly alter the evolutionary trajectory of a species. Genetic assortative mating has been documented in humans, but its existence beyond population stratification (shared ancestry) has been a matter of controversy. Here, we develop a method to measure assortative mating across the genome at 1,044,854 single-nucleotide polymorphisms (SNPs), controlling for population stratification and cohort-specific cryptic relatedness. Using data on 1683 human couples from two data sources, we find evidence for both assortative and disassortative mating at specific, discernible loci throughout the entire genome. Then, using the composite of multiple signals (CMS) score, we also show that the group of SNPs exhibiting the most assortativity has been under stronger recent positive selection. Simulations using realistic inputs confirm that assortative mating might indeed affect changes in allele frequency over time. These results suggest that genetic assortative mating may be speeding up evolution in humans.

Upon the secondary contact of populations, speciation with gene flow is greatly facilitated when the same pleiotropic loci are both subject to divergent ecological selection and induce non-random mating, leading to loci with this fortuitous combination of functions being referred to as 'magic trait' loci. We use a population genetics model to examine whether 'pseudomagic trait' complexes, composed of physically linked loci fulfilling these two functions, are as efficient in promoting premating isolation as magic traits. We specifically measure the evolution of choosiness, which controls the strength of assortative mating. We show that, surprisingly, pseudomagic trait complexes, and to a lesser extent also physically unlinked loci, can lead to the evolution of considerably stronger assortative mating preferences than do magic traits, provided polymorphism at the involved loci is maintained. This is because assortative mating preferences are generally favoured when there is a risk of producing maladapted recombinants, as occurs with non-magic trait complexes but not with magic traits (since pleiotropy precludes recombination). Contrary to current belief, magic traits may not be the most effective genetic architecture for promoting strong premating isolation. Therefore, distinguishing between magic traits and pseudomagic trait complexes is important when inferring their role in premating isolation. This calls for further fine-scale genomic research on speciation genes. [ABSTRACT FROM AUTHOR]

Most of the 500+ cichlid species of Lake Victoria evolved very rapidly in the wake of an adaptive radiation within the last 15,000 years. All 500 species have evolved from just one out of five old cichlid lineages that colonized the lake. Endemic to the Lake Victoria region, Astatoreochromis alluaudi is a member of an old haplochromine lineage that never speciated in the region. Even though the species occurs in a wide range of habitats, there were no indications of evolutionary diversification. Here, we tested predictions of several hypothetical mechanisms that might constrain speciation, including high dispersal rates, a generalist life style and the lack of behavioral assortative mating. Genomic analyses of individuals from 13 populations revealed several genomically distinct groups, associated with major habitat classes, indicating the existence of two distinct ecotypes. We found significant phenotypic differences between these ecotypes in the wild, which were retained under common-garden conditions, potentially indicating heritable phenotypic adaptations. Female mate choice experiments revealed the absence of behavioral assortative mating despite genetic and phenotypic differentiation between ecotypes. We suggest that the lack of coupling between behavioral mating preferences and phenotypic and genetic divergence constrains speciation in this cichlid. [ABSTRACT FROM AUTHOR]

The negative consequences of inbreeding have led animal biologists to assume that mate choice is generally biased against relatives. However, inbreeding avoidance is highly variable and by no means the rule across animal taxa. Even when inbreeding is costly, there are numerous examples of animals failing to avoid inbreeding or even preferring to mate with close kin. We argue that selective and mechanistic constraints interact to limit the evolution of inbreeding avoidance, notably when there is a risk of mating with heterospecifics and losing fitness through hybridization. Further, balancing inbreeding avoidance with conspecific mate preference may drive the evolution of multivariate sexual communication. Studying different social and sexual decisions within the same species can illuminate trade-offs among mate-choice mechanisms. Individuals often mate with relatives, even when it is costly: the 'inbreeding paradox'. Avoiding kin shares neural and molecular mechanisms with other social tasks, such as affiliative behavior and conspecific mate preference. 'Active' inbreeding avoidance battles against nonsexual kin affiliation. Trade-offs between conspecific preference and inbreeding avoidance may constrain or facilitate hybridization. [ABSTRACT FROM AUTHOR]

Many animals exhibit size assortative mating (SAM), but how predation affects it remains largely unknown. We hypothesized that predation risk may turn prey less choosy, disrupting SAM, or reduce the expected reproductive value of mates, maintaining SAM but with different size ratio between mates. Using a manipulative field experiment, we found that desert isopods under risk of scorpion predation maintained SAM, but that males that choose and fight over females were on average smaller for a given female size. Less pairs were formed in risky sites, but there were no differences in female sizes and progeny number, size and age near and away from scorpion burrows. Our complementary behavioral experiments revealed that bigger males stayed longer near safe burrows, and won more male–male contests than smaller conspecifics. Our findings highlight that prey can anticipate future costs of predation and use this information to assess the expected reproductive value of mates. [ABSTRACT FROM AUTHOR]

Non-random mating plays a key role in speciation and impacts the individual life history. Body size is known to be one of the most important traits on which the mate choice is based. Various patterns of body size preference are known in fish, but they have been studied in a limited number of species. Although the climbing perch (Anabas testudineus) is widespread and well known, a few reports of its spawning are published. Moreover, its breeding has only been described in captivity and in most cases it has been artificially induced with hormonal agents. This paper describes the main features of natural spawning of the climbing perch in aquarium compared to induced spawning. A positive size-assortative mating has been revealed. The mating system of Anabas has been shown to be flexible, presumably ranging from monogamy to polygamy. The results are discussed in the context of the general issue of the adequacy of fish behaviour research methods. [ABSTRACT FROM AUTHOR]

We investigated potential information content in red carotenoid-based undertail coverts of 28 pairs of breeding Great Spotted Woodpeckers by comparing plumage reflectance to measures of body condition and reproductive success. Plumage coloration was not significantly associated with sex or age, and did not correlate with body condition or the number of offspring fledged. Further, we found no evidence of assortative mating related to plumage colour. Our research provides an example of an exception from the commonly held hypothesis that carotenoid-based plumage coloration signals individual condition. Future surveys incorporating other plumage traits and physiological measures of condition in Great Spotted Woodpeckers are needed to verify our findings. [ABSTRACT FROM AUTHOR]

Height preferences reflecting positive assortative mating for height--wherein an individual's own height positively predicts the preferred height of their mate--have been observed in several distinct human populations and are thought to increase reproductive fitness. However, the extent to which assortative preferences for height differ strategically for short-term versus long-term relationship partners, as they do for numerous other indices of mate quality, remains unclear. We explore this possibility in a large representative sample of over 500 men and women aged 15-77 from Canada, Cuba, Norway and the United States. Participants' own heights were measured, and they indicated their height preferences for a long-term and short-term mate using graphic stimuli containing metric indices. Replicating the "male-taller norm," participants on average preferred taller-than-average male mates, and shorterthan-average female mates. Positive assortative preferences for height were observed across sexes and samples, however the strength of these height preferences varied with relationship context for men, and not for women. Taller men preferred relatively shorter women for short-term relationships than for long-term relationships, indicating stronger assortative preferences for height in a long-term context. These results provide preliminary evidence that, in addition to mate preferences for other physical traits related to mate quality such as masculinity in the body, face, and voice, assortative preferences for height do vary as a function of expected relationship length, but this was surprisingly only observed in preferences for female height. [ABSTRACT FROM AUTHOR]

Height preferences reflecting positive assortative mating for height—wherein an individual’s own height positively predicts the preferred height of their mate—have been observed in several distinct human populations and are thought to increase reproductive fitness. However, the extent to which assortative preferences for height differ strategically for short-term versus long-term relationship partners, as they do for numerous other indices of mate quality, remains unclear. We explore this possibility in a large representative sample of over 500 men and women aged 15–77 from Canada, Cuba, Norway and the United States. Participants’ own heights were measured, and they indicated their height preferences for a long-term and short-term mate using graphic stimuli containing metric indices. Replicating the “male-taller norm,” participants on average preferred taller-than-average male mates, and shorter-than-average female mates. Positive assortative preferences for height were observed across sexes and samples, however the strength of these height preferences varied with relationship context for men, and not for women. Taller men preferred relatively shorter women for short-term relationships than for long-term relationships, indicating stronger assortative preferences for height in a long-term context. These results provide preliminary evidence that, in addition to mate preferences for other physical traits related to mate quality such as masculinity in the body, face, and voice, assortative preferences for height do vary as a function of expected relationship length, but this was surprisingly only observed in preferences for female height.

In sexually reproducing taxa, reproductive isolation is key to speciation. Given the speed with which behavioral reproductive isolation evolves, this form of isolation is of particular importance to rapidly evolving species. Here we examine behavioral reproductive isolation in a sympatric, congeneric pair of rock‐dwelling cichlids from Lake Malaŵi, testing the hypothesis that females should prefer conspecific males. We used a pair of Labeotropheus, L. fuelleborni Ahl and L. trewavasae Fryer, from the Chidunga Rocks in southwestern Lake Malaŵi, to test this hypothesis, with the prediction that females would approach conspecific males more frequently than they would heterospecific males. When given a choice between a male L. fuelleborni and L. trewavasae, we found that females did approach males of their own species more frequently than males of the opposite species, and that differences in length and the number of eggspots on the anal fin between the stimulus males had no effect on a female's choice. These results are consistent with behavioral reproductive isolation between these sympatric species, and add further support to the hypothesis that sexual selection played a key role in the speciation of cichlid fishes from Lake Malaŵi. [ABSTRACT FROM AUTHOR]

Abstract The maintenance of reproductive isolation in the face of gene flow is a particularly contentious topic, but differences in reproductive behavior may provide the key to explaining this phenomenon. However, we do not yet fully understand how behavior contributes to maintaining species boundaries. How important are behavioral differences during reproduction? To what extent does assortative mating maintain reproductive isolation in recently diverged populations and how important are “magic traits”? Assortative mating can arise as a by‐product of accumulated differences between divergent populations as well as an adaptive response to contact between those populations, but this is often overlooked. Here we address these questions using recently described species pairs of three‐spined stickleback (Gasterosteus aculeatus), from two separate locations and a phenotypically intermediate allopatric population on the island of North Uist, Scottish Western Isles. We identified stark differences in the preferred nesting substrate and courtship behavior of species pair males. We showed that all males selectively court females of their own ecotype and all females prefer males of the same ecotype, regardless of whether they are from species pairs or allopatric populations. We also showed that mate choice does not appear to be driven by body size differences (a potential “magic trait”). By explicitly comparing the strength of these mating preferences between species pairs and single‐ecotype locations, we were able to show that present levels of assortative mating due to direct mate choice are likely a by‐product of other adaptations between ecotypes, and not subject to obvious selection in species pairs. Our results suggest that ecological divergence in mating characteristics, particularly nesting microhabitat may be more important than direct mate choice in maintaining reproductive isolation in stickleback species pairs.

Adaptive introgression is ubiquitous in animals, but experimental support for its role in driving speciation remains scarce. In the absence of conscious selection, admixed laboratory strains of Drosophila asymmetrically and progressively lose alleles from one parental species and reproductive isolation against the predominant parent ceases after 10 generations. Here, we selectively introgressed during 1 year light pigmentation genes of D. santomea into the genome of its dark sibling D. yakuba, and vice versa. We found that the pace of phenotypic change differed between the species and the sexes and identified through genome sequencing common as well as distinct introgressed loci in each species. Mating assays showed that assortative mating between introgressed flies and both parental species persisted even after 4 years (~60 generations) from the end of the selection. Those results indicate that selective introgression of as low as 0.5% of the genome can beget morphologically distinct and reproductively isolated strains, two prerequisites for the delimitation of new species. Our findings hence represent a significant step toward understanding the genome‐wide dynamics of speciation‐through‐introgression. [ABSTRACT FROM AUTHOR]

Although consistent between‐individual differences in behaviour (i.e. animal personality) are ubiquitous in natural populations, relatively few studies have examined how personalities influence the formation of social relationships. Yet, behavioural characteristics of both sexes might be key when it comes to pair‐bond formation, and cooperation with partners to successfully rear offspring. We here use a wild population of dunnocks (Prunella modularis) to first investigate whether individuals mate nonrandomly (i.e. assortative mating) with regard to four behavioural traits—flight‐initiation distance (FID), provisioning, activity and vigilance—that differ in repeatability and have previously been associated with mating patterns and fitness in other species. Second, we test whether an individual's FID is associated with variability in the dunnocks' mating system (i.e. monogamous pairs vs. polygamous groups). Finally, we determine whether FID and provisioning of males and females associate with their reproductive success. We found no statistical support for assortative mating in FID between males and females. Interestingly, in polygamous groups, co‐breeding males differed in their FIDs with dominant alpha males having significantly shorter FIDs compared with subordinate beta‐males. Moreover, there was evidence for assortative mating in provisioning for alpha males and females in polygamous groups. We also found that male provisioning influenced reproductive success of both sexes, whereas female provisioning rates only positively correlated with her own but not their partner(s) reproductive output. Our results suggest that personality differences may have important implications for social relationships, the emergence of different mating patterns and ultimately reproductive success within populations. [ABSTRACT FROM AUTHOR]

Previous studies have reported functional integration between dispersal and other phenotypic traits allowing individuals to alleviate dispersal costs, and such associations can affect dispersal evolution in return. In sexually reproducing species, assortative mating according to dispersal can shape the maintenance of such trait associations. Despite the potentially crucial consequences of dispersal in natural populations, assortative mating for dispersal and its underlying mechanisms remain largely unexplored. Here, we assessed assortative mating for between‐patch dispersal status in a fragmented population of a small passerine bird, the collared flycatcher, and explored whether such assortative mating could result from (i) direct mate choice based on dispersal‐related behavioural (aggressiveness and boldness) and morphological traits (tarsus and wing length), (ii) biased mating due to spatio‐temporal heterogeneity in the distribution of dispersal phenotypes and/or (iii) post‐mating adjustment of dispersal phenotype or dispersal‐related traits. We found intrinsic assortative mating (i.e. positive among‐pair correlation) for current dispersal status (in the year of mating) but not for natal dispersal status, even though we could not exclude it due to limited power. We also found assortative mating for boldness and age category (yearlings vs. older adults), and the probability for pair members to be assorted for current dispersal status was higher when both pair members were of similar boldness score and of the same age compared with mixed‐age pairs. Mate choice based on boldness and age thus appears as a possible mechanism underlying assortative mating for dispersal status. Our analyses however remained correlative, and only an experimental manipulation of these traits could allow inferring causal links. Non‐random mating for dispersal‐related traits may affect the evolution of dispersal syndromes in this population. More work is nevertheless needed to fully assess the evolutionary implications of age‐ and behaviour‐based assortative mating for dispersal. [ABSTRACT FROM AUTHOR]

We investigated morphological differences between sexes, and mating patterns respect to their body size and condition in a wild population of the grey-capped greenfinch Chloris sinica. The results showed that male birds with significant longer bill and wing than female; breeding pairs assortative mated positively by culmen height, wing length, body mass and body condition. We argued that the body condition of greenfinches may be important in mutual mate choice. Male air courtship and incubation feeding behaviour provide evidence that female mate choice may be responsible for sexual dimorphism of bill size and wing length. Mutual mate choice and life histories may be responsible for non-randomly mating pattern by body condition, high quality individual prefer to mate with each other. [ABSTRACT FROM AUTHOR]

Many animals have the ability to learn, and some taxa have shown learned mate preference, which may be important for speciation. The butterfly Heliconius melpomene is a model system for several areas of research, including hybridization, mate selection and speciation, partially due to its widespread diversity of wing patterns. It remains unclear whether social experience shapes realized mating preferences in this species. Here we test whether previous experience with a female influences male mate preference for two H. melpomene subspecies, H. m. malleti and H. m. rosina. We conducted no-choice assays to determine whether male courtship (versus no courtship) and latency to court differed between naïve males and males with previous exposure to a sexually mature, virgin female. To test whether assortative courtship preference is learned in H. melpomene , males were either paired with a female who shared their phenotype or one who did not. Naïve H. m. malleti males courted assortatively, while naïve H. m. rosina males did not. When data were pooled across subspecies, experienced males reduced their courting relative to naïve males, suggesting that social experience with a female sans copulation may be perceived as a negative experience. This effect was likely driven by experienced H. m. malleti males, who reduced their courting relative to naïve males when analysed independently, while experienced H. m. rosina males did not. Our results suggest that social experience can influence male mating behaviour in H. melpomene and has the potential to contribute to the high rate of diversification observed in Heliconius butterflies. • Learning whom to court may be either adaptive or maladaptive when around heterospecifics. • Using no-choice assays, we tested for courtship learning in male H. melpomene. • Male H. melpomene reduced courtship after encountering but not copulating with a female. • H. melpomene males can use past experience to inform current mating decisions. • This may be adaptive if encounters with heterospecific, unreceptive females are common. [ABSTRACT FROM AUTHOR]

Similarity in facial and other physical characteristics has been recognized as one aspect of reproductive mate choice in humans. Despite the fact that parental similarity degree may affect off spring already in the early stages of their prenatal development, just a very few empirical studies have focused on the consequences of this non-random process so far. This study included three goals: (1) to test the hypothesis of body assortative mating in humans, (2) to find a relationship between physical similarity of parents and the growth curves of their off spring and (3) to find specific trends in the growth of off spring connected to parental assortative mating. Therefore, the similarities of parents in physical features were analysed in relation to the descriptors of the growth curves of their off spring (n = 184 mother-father-child triads from the Brno Growth Study database). In comparison to randomly generated pairs, real partners were not more similar to each other in any of the observed trait. However, some physical features correlated (mostly positively) between partners. Relationships between physical similarity of parents and the descriptors of the growth curves of their off spring were found. However, parental similarity in various features affected the growth of their off spring diff erently. [ABSTRACT FROM AUTHOR]

As biparental care is crucial for breeding success in Procellariiformes seabirds (i.e. albatrosses and petrels), these species are expected to be choosy during pair formation. However, the choice of partners is limited in small‐sized populations, which might lead to random pairing. In Procellariiformes, the consequences of such limitations for mating strategies have been examined in a single species. Here, we studied mate choice in another Procellariiforme, Bulwer's petrel Bulweria bulwerii, in the Azores (ca 70 breeding pairs), where the species has suffered a dramatic population decline. We based our approach on both a 11‐year demographic survey (capture–mark–recapture) and a genetic approach (microsatellites, n = 127 individuals). The genetic data suggest that this small population is not inbred and did not experience a genetic bottleneck. Moreover, pairing occurred randomly with respect to genetic relatedness, we detected no extrapair parentage (n = 35 offspring), and pair fecundity was unrelated to relatedness between partners. From our demographic survey, we detected no assortative mating with respect to body measurements and breeding experience and observed very few divorces, most of which were probably forced. This contrasts with the pattern previously observed in the much larger population from the Selvagens archipelago (assortative mating with respect to bill size and high divorce rate). We suggest that the Bulwer's petrels from the Azores pair with any available partner and retain it as long as possible despite the fact that reproductive performance did not improve with pair common experience, possibly to avoid skipping breeding years in case of divorce. We recommend determining whether decreased choosiness during mate choice also occurs in reduced populations of other Procellariiform species. This might have implications for the conservation of small threatened seabird populations. [ABSTRACT FROM AUTHOR]

Disassortative mating is a rare form of mate preference that promotes the persistence of polymorphism. While the evolution of assortative mating and its consequences for trait variation and speciation have been extensively studied, the conditions enabling the evolution of disassortative mating are still poorly understood. Mate preferences increase the risk of missing mating opportunities, a cost that can be compensated by a greater fitness of offspring. Heterozygote advantage should therefore promote the evolution of disassortative mating, which maximizes the number of heterozygous offspring. From the analysis of a two-locus diploid model with one locus controlling the mating cue under viability selection and the other locus coding for the level of disassortative preference, we show that heterozygote advantage and negative frequency-dependent viability selection acting at the cue locus promote the evolution of disassortative preferences. We predict conditions of evolution of disassortative mating coherent with selection regimes acting on traits observed in the wild. We also show that disassortative mating generates sexual selection, which disadvantages heterozygotes at the cue locus, limiting the evolution of disassortative preferences. Altogether, our results partially explain why this behavior is rare in natural populations. [ABSTRACT FROM AUTHOR]

Men with light eyes lack the dominant gene allele that codes for dark-brown eyes. Pairing with a woman who lacks the same allele must increase paternity confidence in these men, because any children with dark eyes would be extremely unlikely to have been fathered by them. This notion implies that men with light (blue or green) eyes should (1) prefer light-eyed women, especially in a long-term context, and (2) feel more threatened by light-eyed than by dark-eyed rivals. Yet because choosiness is costly and paternity concerns are entirely driven by the prospect of paternal investment, any such inclinations would be adaptive only in men who expect to invest in their children. Here I test these ideas using the data of over 1000 men who rated the facial attractiveness of potential partners, and the threat of potential rivals, whose eye color had been manipulated. Light-eyed men liked light-eyed women better (particularly as long-term companions), and feared light-eyed rivals more, than did dark-eyed men. An exploratory analysis showed that these large, robust effects disappeared in men who had felt rejected by their fathers while growing up—suggesting that such men are not expecting to invest in their own children either. [ABSTRACT FROM AUTHOR]

Reinforcement translocations are increasingly utilised in conservation with the goal of achieving genetic rescue. However, concerns regarding undesirable results, such as genetic homogenisation or replacement, are widespread. One factor influencing translocation outcomes is the rate at which the resident and the introduced individuals interbreed. Consequently, post-release mate choice is a key behaviour to consider in conservation planning. Here we studied mating, and its consequences for genomic admixture, in the North Island brown kiwi Apteryx mantelli population on Ponui Island which was founded by two translocation events over 50 years ago. The two source populations used are now recognised as belonging to two separate management units between which birds differ in size and are genetically differentiated. We examined the correlation between male and female morphometrics for 17 known pairs and quantified the relatedness of 20 pairs from this admixed population. In addition, we compared the genetic similarity and makeup of 106 Ponui Island birds, including 23 known pairs, to birds representing the source populations for the original translocations. We found no evidence for size-assortative mating. On the contrary, genomic SNP data suggested that kiwi of one feather did not flock together, meaning that mate choice resulted in pairing between individuals that were less related than expected by random chance. Furthermore, the birds in the current Ponui Island population were found to fall along a gradient of genomic composition consistent with non-clustered representation of the two parental genomes. These findings indicate potential for successful genetic rescue in future Apteryx reinforcement translocations, a potential that is currently under utilised due to restrictive translocation policies. In light of our findings, we suggest that reconsideration of these policies could render great benefits for the future diversity of this iconic genus in New Zealand.

Rapidly changing environments may weaken sexual selection and lead to indiscriminate mating by interfering with the reception of mating signals or by increasing the costs associated with mate choice. If temperature alters sexual selection, it may impact population response and adaptation to climate change. Here, we examine how differences in temperature of the mating environment influence reproductive investment in the European corn borer moth (Ostrinia nubilalis). Mate preference in this species is known to be related to pheromone usage, with assortative mating occurring between genetically distinct E and Z strains that differ in the composition of female and male pheromones. We compared egg production within and between corn borer lines derived from four different populations that vary in pheromone composition and other traits. Pairs of adults were placed in a mating environment that matched the pupal environment (ambient temperature) or at elevated temperature (5°C above the pupal environment). At ambient temperature, we found that within‐line pairs produced eggs sooner and produced more egg clusters than between‐line pairs. However, at elevated temperature, between‐line pairs produced the same number of egg clusters as within‐line pairs. These results suggest that elevated temperature increased investment in matings with typically less preferred, between‐line mates. This increased investment could result in changes in gene flow among corn borer populations in warming environments. [ABSTRACT FROM AUTHOR]

Abstract Maynard Smith's (American Naturalist, 1966, 100, 637) suggestion that in some cases a prerequisite for speciation is the existence of local ecological adaptations has not received much attention to date. Here, we test the hypothesis using a model like that of Maynard Smith but differing in the way animals disperse between niches. In previous studies, males disperse randomly between niches but females stay put in their natal niche. As a first step toward generalizing the model, we here analyze the case that equal proportions of the two sexes disperse between niches before breeding. Supporting Maynard Smith's (1966) hypothesis, we find that once local adaptations are established, a neutral mating cue at an independent locus can rapidly enable speciation in populations with a suitable mechanism for phenotype matching. We find that stable ecological polymorphisms are relatively insensitive to the strength of selection, but depend crucially on the extent of dispersal between niches, with a threshold of ~5% if population sizes in two niches are equal. At higher levels of dispersal, ecological differentiation is lost. These results contrast with those of earlier studies and shed light on why parapatric speciation is limited by the extent of gene flow. Our testable model provides a candidate explanation for the rapid speciation rates, diversity of appearance and occurrence of “species flocks” observed among some African cichlids and neotropical birds and may also have implications for the occurrence of punctuational change on phylogenies.

In species with long-term pair bonds, such as zebra finches, evaluating the quality of potential mates is critically important. Courtship is an opportunity to evaluate information from dynamic behavioural cues. Personality traits, as stable individual differences in behaviour, could predict the quality of a potential mate. How might personality traits influence mate choice? We examined the influence of several personality traits, including exploration, aggression, and social preference, on pair formation in zebra finches. We provided birds with a variety of potential mates and allowed them to select a pair partner. Our semi-naturalistic mate choice paradigm allowed birds to observe social information over an extended period, simulating the challenges of social evaluation that birds encounter in the wild. We found that pairing is influenced by personality, with birds selecting mates similar to them in exploration. The partner's exploration score relative to their own was more important than the absolute exploration score. [ABSTRACT FROM AUTHOR]

Despite the important roles of assortative mating for understanding evolutionary processes, our knowledge on the variation in assortative mating across populations and breeding periods has been overshadowed by the greater attention given to general patterns. Obtaining data on mating pairs are difficult for most species; therefore, researchers often group data from different populations or breeding periods, which can increase positive biases in detecting and estimating assortative mating. We used a meta‐analytic approach to investigate the biases caused by spatially or temporally pooling data and the assortative mating consistency across populations and breeding periods. We describe assortative mating patterns across and within animal taxa. We performed a systematic review to search studies reporting measures of size‐assortative mating (SAM). Grouping data from multiple populations and seasons incurred positive biases. Overall, assortative mating moderately exhibited low repeatability in space and time, but it was inconsistent for most taxa. After excluding pooled measures, the average estimate for assortative mating was moderate and positive. Thus, our findings demonstrate that pooling data can produce misleading results. We also highlight the importance of further investigation of hypotheses that explain spatial and temporal variation in assortative mating, after its detection. Our study reinforces the significance of investigating mating patterns at various spatial and temporal scales before drawing broad conclusions. [ABSTRACT FROM AUTHOR]

The presence of persistent polymorphisms within natural populations elicits the question of how such polymorphisms are maintained. All else equal, genetic drift and natural selection should remove genetic variants from populations. Disassortative mating and overdominance are potential mechanisms for maintaining variation within populations. Here, we consider the potential role of these mechanisms in maintaining variation in colour pattern in the tortoise beetle, Chelymorpha alternans. Five colour morphs distinguished by elytral and pronotal coloration are largely determined by a single locus of large effect with four segregating alleles. As many as four morphs co‐occur in natural populations. We first assessed whether disassortative mating might maintain this polymorphism. To test for assortative and disassortative mating, we paired females with two males, one with the same colour pattern as the female and one with a different colour pattern and examined the colour patterns of the offspring. We found strong evidence for random mating as a function of colour pattern. We next assessed whether differences in offspring survival among assortative and disassortative male‐female pairs maintain colour variation. Crosses involving disassortative pairings had significantly higher offspring survival during development and resulted in more adult progeny. This result is consistent with the effects of overdominance, whereby outcrossed individuals have higher fitness than their homozygous counterparts. Overall, differences in offspring survival appear to play a greater role in maintaining polymorphisms than nonrandom mating in species. [ABSTRACT FROM AUTHOR]

People do not choose their partners randomly. Assortative mating can be either positive (homogamy), meaning people couple with self-similar partners, or negative (heterogamy, complementarity), meaning they couple with self-different partners. More than a hundred years of research have shown that in mate choice the principle of homogamy is significantly more prevalent. Being one of the most prominent principles of pairing, homogamy is studied across disciplines, varying from psychology, sociology, psychiatry, ethology, to anthropology. The aim of this narrative review is to comprehensively present and critically summarize the current state of knowledge in the field of positive assortative pairing, with the focus on empirical support (partner similarity in sociodemographic, psychological and physical characteristics), factors influencing homogamy (sexual orientation or culture) and the effects of homogamy on the relationship (satisfaction and stability of the relationship). Finally, the methodological pitfalls of the research are discussed and the directions for the future research are suggested. Due to the interdisciplinarity of the topic and the large number of papers investigating positive assortative pairing, we believe that this review will help readers to navigate themselves through the complex issue of homogamy. [ABSTRACT FROM AUTHOR]

The maintenance of reproductive isolation in the face of gene flow is a particularly contentious topic, but differences in reproductive behavior may provide the key to explaining this phenomenon. However, we do not yet fully understand how behavior contributes to maintaining species boundaries. How important are behavioral differences during reproduction? To what extent does assortative mating maintain reproductive isolation in recently diverged populations and how important are "magic traits"? Assortative mating can arise as a by‐product of accumulated differences between divergent populations as well as an adaptive response to contact between those populations, but this is often overlooked. Here we address these questions using recently described species pairs of three‐spined stickleback (Gasterosteus aculeatus), from two separate locations and a phenotypically intermediate allopatric population on the island of North Uist, Scottish Western Isles. We identified stark differences in the preferred nesting substrate and courtship behavior of species pair males. We showed that all males selectively court females of their own ecotype and all females prefer males of the same ecotype, regardless of whether they are from species pairs or allopatric populations. We also showed that mate choice does not appear to be driven by body size differences (a potential "magic trait"). By explicitly comparing the strength of these mating preferences between species pairs and single‐ecotype locations, we were able to show that present levels of assortative mating due to direct mate choice are likely a by‐product of other adaptations between ecotypes, and not subject to obvious selection in species pairs. Our results suggest that ecological divergence in mating characteristics, particularly nesting microhabitat may be more important than direct mate choice in maintaining reproductive isolation in stickleback species pairs. [ABSTRACT FROM AUTHOR]

The African turquoise killifish (Nothobranchius furzeri) is the shortest-lived vertebrate research model. It is also sexually dimorphic, making it suitable for studying sexual selection. We take advantage of a natural tail colour polymorphism in males and investigate female responses to computer animations of males that differ in this phenotype. Our findings indicate that GRZ (Gonarezhou) females prefer animated males with traits specific to their strain (a yellow tail with a black band) compared to males exhibiting traits from another strain of the same species (a red tail). When females were simultaneously shown animations of both males, they spent significantly more time on the side of the tank where the yellow-tailed animation was visible, and significantly more time interacting with the yellow-tailed animation. Given these repeatable responses and the availability of genomic resources, N. furzeri represents an excellent, untapped model for studying the genetic basis of preferences and reproductive behaviours. [ABSTRACT FROM AUTHOR]

Optimization of chances for healthy offspring is thought to be one of the factors driving mate choice and compatibility of the major histocompatibility complex (MHC) is assumed to determine the offspring's fitness. While humans have been claimed to be able to perceive information of MHC compatibility via the olfactory channel, it remains unknown whether humans use such information for mate choice. By investigation of 3691 married couples, we observed that the high polymorphism of MHC leads to a low chance for homozygous offspring. MHC similarity between couples did not differ from chance, we hence observed no MHC effect in married couples. Hormonal contraception at the time of relationship initiation had no significant effect towards enhanced similarity. A low variety of alleles within a postcode area led to a higher likelihood of homozygous offspring. Based on this data, we conclude that there is no pattern of MHC dis-assortative mating in a genetically diverse Western society. We discuss the question of olfactory mate preference, in-group mating bias and the high polymorphism as potential explanations. [ABSTRACT FROM AUTHOR]

Consistent individual differences in behavior [i.e., behavioral types (BTs)], are common across the animal kingdom. Consistency can make behavior an adaptive trait for mate choice decisions. Here, we present a conceptual framework to explain how and why females might evaluate a male's BT before mating. Because BTs are consistent across time or context, a male's BT can be a reliable indicator of his potential to provide direct benefits. Heritable BTs can enable informed mate choice via indirect benefits. Many key issues regarding patterns of mate choice, including sensory biases, context dependence, and assortative mating apply to BT-dependent mate choice. Understanding the relationship between BTs and mate choice may offer insights into patterns of variation and consistency common in behavioral traits. Acknowledging the existence of consistent differences among individuals in behavior [i.e., behavioral types (BTs)] yields new insights on patterns of mate choice. Because BTs are both consistent over time and context, and are heritable, mate choice based on the partner's behavioral type can be adaptive. Choosing an individual's BT can affect its adaptive mate choice. Due to complex interactions between the sexes, their BTs, and environmental context, BT-dependent mate choice may help to explain the maintenance of variation between individuals in behavioral type. In addition, the social context and benefit of honest signaling that is a part of mate choice may contribute to why we see consistency within an individual in BT. [ABSTRACT FROM AUTHOR]

When divergent populations are connected by gene flow, the establishment of complete reproductive isolation usually requires the joint action of multiple barrier effects. One example where multiple barrier effects are coupled consists of a single trait that is under divergent natural selection and also mediates assortative mating. Such multiple‐effect traits can strongly reduce gene flow. However, there are few cases where patterns of assortative mating have been described quantitatively and their impact on gene flow has been determined. Two ecotypes of the coastal marine snail, Littorina saxatilis, occur in North Atlantic rocky‐shore habitats dominated by either crab predation or wave action. There is evidence for divergent natural selection acting on size, and size‐assortative mating has previously been documented. Here, we analyze the mating pattern in L. saxatilis with respect to size in intensively sampled transects across boundaries between the habitats. We show that the mating pattern is mostly conserved between ecotypes and that it generates both assortment and directional sexual selection for small male size. Using simulations, we show that the mating pattern can contribute to reproductive isolation between ecotypes but the barrier to gene flow is likely strengthened more by sexual selection than by assortment. [ABSTRACT FROM AUTHOR]

The authors discuss assortative mating, the tendency--important for increased genetic variation--of individuals to mate with the phenotypically similar at rates greater than chance. Influenced by many factors--physical characteristics like height and weight and demographic elements like behavior and attitudes, economic status and education, church attendance and ethnic identity, politics and personality--assortative mating has been considered with regard to having a good sense of humor but never to being playful or being fun loving. Based on a study of 254 undergraduates, the authors examine how these variables correlate with the search for desirable mates by adults and suggest the variables are indeed subject to assortative mating. [ABSTRACT FROM AUTHOR]

Non-random mating has a significant impact on the evolution of organisms. Here, I developed a modelling framework for discrete traits (with any number of phenotypes) to explore different models connecting the non-random mating causes (mate competition and/or mate choice) and their consequences (sexual selection and/or assortative mating). I derived the formulaefor the maximum likelihood estimates of each model and used information criteria to perform multi-model inference. Simulation results showed a good performance of both model selection and parameter estimation. The methodology was applied to ecotypes data of the marine gastropod Littorina saxatilis from Galicia (Spain), to show that the mating pattern is better described by models with two parameters that involve both mate choice and competition, generating positive assortative mating plus female sexual selection. As far as I know, this is the first standardized methodology for model selection and multi-model inference of mating parameters for discrete traits. The advantages of this framework include the ability of setting up models from which the parameters connect causes, as mate competition and mate choice, with their outcome in the form of data patterns of sexual selection and assortative mating. For some models, the parameters may have a double effect i.e. they produce sexual selection and assortative mating, while for others there are separated parameters for one kind of pattern or another. From an empirical point of view, it is much easier to study patterns than processes and, for this reason, the causal mechanisms of sexual selection are not so well known as the patterns they produce. The goal of the present work is to propose a new tool that helps to distinguish among different alternative processes behind the observed mating pattern. The full methodology was implemented in a software called InfoMating (available at http://acraaj.webs6.uvigo.es/InfoMating/Infomating.htm). [ABSTRACT FROM AUTHOR]

Assortative mating is a universal feature of human societies, and individuals from ethnically diverse populations are known to mate assortatively based on similarities in genetic ancestry. However, little is currently known regarding the exact phenotypic cues, or their underlying genetic architecture, which inform ancestry-based assortative mating. We developed a novel approach, using genome-wide analysis of ancestry-specific haplotypes, to evaluate ancestry-based assortative mating on traits whose expression varies among the three continental population groups – African, European, and Native American – that admixed to form modern Latin American populations. Application of this method to genome sequences sampled from Colombia, Mexico, Peru, and Puerto Rico revealed widespread ancestry-based assortative mating. We discovered a number of anthropometric traits (body mass, height, and facial development) and neurological attributes (educational attainment and schizophrenia) that serve as phenotypic cues for ancestry-based assortative mating. Major histocompatibility complex (MHC) loci show population-specific patterns of both assortative and disassortative mating in Latin America. Ancestry-based assortative mating in the populations analyzed here appears to be driven primarily by African ancestry. This study serves as an example of how population genomic analyses can yield novel insights into human behavior.