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Ecological speciation is an evolutionary process driven by divergent natural selection in heterogeneous environments characterised by diverse resources and habitats. Increasing evidence supports the occurrence of this phenomenon in nature. One frequently cited example among mammals is the Upper Galilee Mountains blind mole rat, Nannospalax galili. Over a decade ago, it was proposed that this species is undergoing incipient ecological speciation due to the sharply contrasting ecological conditions resulting from the presence of pale rendzina and dark basaltic soils. In this study, we examined the population genetic structure and gene flow between mole rats inhabiting these two distinct soil types at two localities in Northern Israel, Rihaniya and Gush Halav, each containing sites on both rendzina and basaltic soil types. We used eight microsatellite markers to assess genetic differentiation. The results indicate that in Rihaniya, where blind mole rats from both soils were sampled in close proximity, the genetic divergence between animals from the different soil types was the lowest. In Gush Halav, the genetic differentiation increased with geographic distance between sampled sites, indicating an isolation-by-distance effect. The presence of migrants and first-generation hybrids in both soils at both localities suggests that blind mole rats migrate and mate relatively frequently between the two soil types. These findings imply that ecological speciation in N. galili may be in its very early stages, with no clear evidence of assortative mating yet. Further research is needed to understand this phenomenon in this study system. [ABSTRACT FROM AUTHOR]

To disentangle genetic and environmental contributions to individual differences, classical twin models (CTMs) are predominantly used. Prior research revealed several conditions under which CTMs spawn biased heritability and environmentality estimates, including the simultaneous relevance of nonadditive genetic and shared environmental influences, the presence of assortative mating, and passive gene-environment covariance. Nuclear twin family models (NTFMs), adding information from parents of twins, can handle these conditions. Little is known, however, on the actual impact of such conditions considering the empirical properties displayed by various personality-related phenotypes. The present study therefore investigated differences between NTFMs and CTMs in terms of error-adjusted heritability and environmentality across 93 personality-relevant constructs based on data from 636 twin pairs and 320 parents. Overall, NTFMs resulted in significantly lower heritability and higher environmentality estimates, suggesting an overall overestimation of heritability in CTMs. These trends pertained to about two-thirds of the investigated constructs, but reversely directed changes were detectable under specific conditions. We discuss the extent to which the assumptions underlying CTMs might bias conclusions regarding genetic and environmental contributions to personality differences and demonstrate benefits of NTFMs. Furthermore, we provide user tutorials for implementing CTMs and NTFMs based on the open-source and user-friendly statistical program JASP. [ABSTRACT FROM AUTHOR]

Local genetic correlation analysis is an important tool for identifying genetic loci with shared biology across traits. Recently, Border et al. have shown that the results of these analyses are confounded by cross-trait assortative mating (xAM), leading to many false-positive findings. Here, we describe LAVA-Knock, a local genetic correlation method that builds off an existing genetic correlation method, LAVA, and augments it by generating synthetic data in a way that preserves local and long-range linkage disequilibrium (LD), allowing us to reduce the confounding induced by xAM. We show in simulations based on a realistic xAM model and in genome-wide association study (GWAS) applications for 630 trait pairs that LAVA-Knock can greatly reduce the bias due to xAM relative to LAVA. Furthermore, we show a significant positive correlation between the reduction in local genetic correlations and estimates in the literature of cross-mate phenotype correlations; in particular, pairs of traits that are known to have high cross-mate phenotype correlation values have a significantly higher reduction in the number of local genetic correlations compared with other trait pairs. A few representative examples include education and intelligence, education and alcohol consumption, and attention-deficit hyperactivity disorder and depression. These results suggest that LAVA-Knock can reduce confounding due to both short-range LD and long-range LD induced by xAM. Performing local genetic correlation is important for identifying genetic loci with shared biology across traits. However, results can be confounded by cross-trait assortative mating (xAM), leading to many false-positive findings. Ma et al. propose LAVA-Knock, a local genetic correlation method via knockoffs that is shown to reduce the confounding. [ABSTRACT FROM AUTHOR]

Theory predicts that performance-based habitat choice 1,2,3 —where individuals select environments based on their local performance—should be widespread in nature and significantly influence ecological and evolutionary processes, including local adaptation, population divergence, reproductive isolation, and speciation. 2,4,5,6,7,8,9 However, experimental evidence supporting these predictions has been largely lacking. In this study, we addressed this by inducing performance-based habitat choice in wild tree sparrows (Passer montanus) through the manipulation of differential access to transponder-operated feeders in two adjacent woodland areas. Sparrows overwhelmingly chose to move to and breed in the area where their feeding performance was highest, leading to local adaptation and increased reproductive success. Moreover, this non-random movement led to a high degree of assortative mating for transponder type and to reproductive isolation with respect to this ecological trait—all within a single generation. Our findings provide an empirical proof of principle that performance-based habitat choice can drive adaptive population divergence, even in the absence of divergent natural selection, underscoring its potential role as a key mechanism in ecological and evolutionary dynamics. This highlights the importance of integrating performance-based habitat choice into broader frameworks of adaptation and speciation, especially in the context of rapidly changing environments. [Display omitted] • Performance-based habitat choice affected the location of breeding • This resulted in assortative mating with respect to local performance • It translated into reproductive isolation between locally adapted subpopulations • Adaptive divergence can occur without currently operating natural selection Munar-Delgado et al. provide experimental evidence for ecological and evolutionary impacts of performance-based habitat choice. It can affect breeding location and success, lead to assortative mating for local performance, and drive reproductive isolation between adaptively diverging populations—without currently operating natural selection. [ABSTRACT FROM AUTHOR]

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]

Background: Genomic mating (GM) can effectively control the growth rate of inbreeding in population and achieve long-term sustainable genetic progress. However, the design of GM method and assessment of its effects during long-term selection have not been fully explored in beef cattle breeding. Results: In this study, we constructed a simulated population based on the real genotypes of Huaxi cattle, where five generations of simulated breeding were carried out using the genomic optimal contribution selection (GOCS), genetic algorithms strategy and three traditional mating strategies. During the breeding process, genetic parameters including average genomic estimated breeding value (GEBV), genetic gain values ( Δ G ), the rate of inbreeding values ( Δ F ) were calculated and compared across generations. Our results showed that the GM method could significantly improve the genetic gain while effectively controlling the inbreeding accumulation within the population. When using the GM method, there was an increase in genetic gain for Huaxi cattle ranging from 1.1% to 25.6% compared to traditional mating strategy, with inbreeding decreasing in the range of 5.8% to 36.2%. Validation using the real dataset from Huaxi cattle further confirmed our findings from the simulated study, offspring populations using the GM strategy exhibited a 7.3% increase in genetic gain compared to positive assortative mating. Conclusions: These findings suggest that the GM method shows potential for achieving sustainable genetic gain and could be utilized during long-term selection in beef cattle breeding. [ABSTRACT FROM AUTHOR]

Evolutionary theory predicts that assortative mating is crucial for sympatric speciation by generating reproductive isolation between diverging populations. Here, we investigate the potential of form-assortative mating, an assumed mating pattern in lampreys, for sympatric speciation. By continuously recording mating activity between anadromous and freshwater-resident forms of L. camtschaticum that greatly differ in body size, we show that lampreys tend to mate with individuals of similar size in experimental conditions. However, we highlight that this pattern does not result from a choice of same-form partner but is the result of the simultaneous action of a preference of males—whatever their size—for large anadromous females, a higher competitive ability of aggressive males and physical constraints on heteroform pairs. Moreover, we do not advocate that sympatric speciation, as the sole consequence of form-assortative mating through sexual selection, is a plausible mechanism for the diversification of lampreys as a significant number of sneaking behaviors were observed in freshwater-resident males toward large anadromous females. Broader attention should be given to mechanisms other than the sexual selection that may lead to form-assortative mating, such as variations in the spatial or temporal distribution of alternative forms during reproductive season. [ABSTRACT FROM AUTHOR]

Obligate brood parasitism is a peculiar behaviour found in some bird species. The costs for their hosts can be high, generating selection for active defence strategies including foreign egg and chick rejection. Only one of these two rejection strategies seems to be expressed in any given host species, which in turn selects for mimicry in parasites only at one stage of the nesting cycle. Here, I review the cues used by hosts to recognise brood parasites in the nest and the behaviours to neutralise them, as well as counteradaptations found in parasites. Furthermore, I link these adaptations with theoretical and known processes of genetic transmission of the involved mimicry traits to the offspring. I suggest that the stage at which the parasite is recognised by the host can impose selection on the mating system of the parasite and increase the likelihood of speciation. When hosts discriminate against foreign eggs, interbreeding by male and female parasites reared by different hosts may impede speciation, but not the evolution of egg mimicry if inherited through the maternal line (via the W‐chromosome). When hosts discriminate against chicks, an effective mimetic phenotype requires autosomal (or Z‐chromosome) inheritance to allow expression in both male and female chicks, thus favouring assortative mating in the parasites, and potentially leading to speciation. To my knowledge, this review is the first to link host defence strategies with their potential consequences for speciation in brood parasites. I suggest future steps to fill knowledge gaps in brood parasitism. [ABSTRACT FROM AUTHOR]

Understanding patterns of diversification necessarily requires accounting for both the generation and the persistence of species. Formal models of speciation genetics, however, focus on the generation of new species without explicitly considering the maintenance of biodiversity (e.g., coexistence, the focus of ecological studies of diversity). Consequently, it remains unclear whether and how new species will coexist following a speciation event, a gap limiting our ability to understand the rate-limiting controls of diversification over macroevolutionary timescales. To connect coexistence and speciation theory and assess the relative importance of ecological versus genetic constraints in diversification events, we develop a deterministic, three-locus, population-genetic model that includes a skewed distribution of available resources (to generate variation in fitness differences), frequency-dependent competition, and assortative mating. Both ecology and genetics play vital and interacting roles in shaping initial speciation events and long-term eco-evolutionary outcomes. Ecological constraints are especially important when fitness differences are large and competition remains strong among dissimilar phenotypes. Ephemeral species can occur in our model and are typically lost because of competitive exclusion, a result demonstrating that species persistence may serve as the rate-limiting control of long-term diversification rates. More broadly, our model adds evidence that the unification of ecological and evolutionary (including genetic) perspectives on biodiversity is needed to predict large-scale patterns. [ABSTRACT FROM AUTHOR]

Objective: This study examines, for the first time in Canada, the relationship between how different‐sex couples meet and assortative mating on education, race, nativity, and age. Background: Extending research on how the likelihood of heterogamy differed between offline and online dating, this study disentangles the implications of institutional and third‐person influences from those of online dating for configuring the patterns of heterogamy and gender asymmetry in assortative mating. Method: Data from a 2018 national survey are analyzed using (multinomial) logit models. Results: Educational heterogamy and nativity heterogamy are higher, but age heterogamy appears lower, in online than offline dating. Next, specific channels of offline dating—formal institutions, social ties, and other channels—are distinguished and compared with online dating. Online dating tends to entail higher educational and nativity heterogamy (vs. meeting through formal institutions), higher racial and nativity heterogamy but lower age heterogamy (vs. meeting through social ties), and higher educational heterogamy (vs. meeting through other offline channels). Further considering gender asymmetry shows that online dating is associated with higher educational hypergyny (more‐educated man, less‐educated woman) than meeting through other offline channels; higher nativity hypogyny (immigrant man, native‐born woman) than meeting offline (overall, formal institutions, social ties); and lower age hypergyny (older man, younger woman) than meeting offline through social ties. Conclusion: The findings help untangle the roles of institutional, social, and digital forces in shaping assortative mating. They illustrate the importance of leveraging theoretically informed comparisons to understand how online and offline dating configures assortative mating and its gender‐asymmetric patterns. [ABSTRACT FROM AUTHOR]

Objective Background Method Results Conclusion This study investigates youth–status exchange in urban China, a country rooted in traditional gender roles and gendered mate selection preferences.Status exchange operates as a mechanism through which social boundaries are crossed in intermarriage. In contrast to the extensive research on marital exchanges involving ascribed traits and achieved characteristics, limited attention has been paid to youth–status exchange.Using data from the 2003 to 2021 Chinese General Survey, this study operationalizes the youth–status exchange as age–education exchange, employing log‐linear models to examine the exchange patterns and trends by controlling for marginal differences and confounding trends.The findings reveal robust gender‐asymmetric youth–education exchange patterns in urban China from 1981 to 2021. Women show strong evidence of trading their youth for their spouse's education, whereas men exhibit resistance to the exchange. The strength of exchange between women's youth and men's education increased noticeably for the 2010–2021 marriage cohort. Additionally, men's delayed marriage intensifies the exchange between women's youth and men's education, consistent with men's preference for women with “fixed ideal age.”Persistent patriarchal ideals and traditional gender roles in urban China valorize women's youth while devaluing their achieved status, thereby promoting the exchange between women's youth and men's status. This exchange also serves as a mobility channel for young women to secure more advantageous marriages. [ABSTRACT FROM AUTHOR]

Couple formation and assortative mating significantly influence societal structures, as marriages between individuals from diverse geographical or social backgrounds promote intra-family diversity. Understanding these patterns is crucial for grasping the demographic processes that shape contemporary societies. However, the scarcity of comprehensive data has impeded progress in this area. This paper aims to fill this gap by investigating assortative mating trends in the United States among birth cohorts from 1700 to 1910, utilizing data from FamiLinx, an online crowdsourced genealogical database. We focus on two primary dimensions: migration background (including natives, first and second-generation migrants) and age at marriage. Our analysis yields three major findings. First, we document significant changes in assortative mating trends over time, reflecting the dynamic nature of mate selection and its responsiveness to societal shifts. Second, we uncover substantial heterogeneity in assortative mating patterns across different social groups, indicating varying social dynamics and preferences. Third, we illustrate how these trends can be differently interpreted depending on whether the perspective is individual or familial. Additionally, we explore the advantages and limitations of using online genealogical data for historical studies of assortative mating, highlighting its potential for offering new insights while acknowledging the challenges posed by data quality and representativeness. [ABSTRACT FROM AUTHOR]

A preference for mating with conspecifics over heterospecifics is fundamental to the maintenance of species diversity in sexually reproducing organisms. This type of positive assortative preference results in sexual isolation, and a reduction in gene flow between species due to differences in mate choice. The proximate and ultimate causes of sexual isolation therefore constitute active areas of research in evolutionary biology. Sexual isolation is often stronger between closely related sympatric species as compared to allopatric species because of processes such as reinforcement. In addition, traditional theories of sexual selection suggest that because reproduction is more costly to females, they should be the choosier sex and play a more central role in sexual isolation. We conducted a comparative analysis of assortative mate preferences in males and females of sympatric and allopatric species pairs of darters (fish genus Etheostoma). We performed a meta‐analysis of 17 studies, encompassing 21 species, in which assortative preference was measured when fish were (in most cases) allowed only visual information. As expected, we found stronger preferences for conspecifics over heterospecifics across studies and species. However, we did not find an effect of sympatry or sex on the strength of preference for conspecifics, but rather remarkable variation across species. We offer several testable hypotheses to explain the variation we observed in the strength of assortative preference. [ABSTRACT FROM AUTHOR]

Parental education may influence children's development both additively and multiplicatively. While parental educational attainment enriches financial and cultural investments in children's development, parental educational homogamy is associated with consistency and agreement in parenting practices that may benefit the children. In this paper, using the 2014 China Education Panel Survey, we examine relationships between parental education, regarding both parental educational attainment and educational assortative mating, and children's subjective wellbeing, measured by depressive symptoms and self-rated confidence in the future. We also explore the mediating mechanisms linking parental education and children's subjective wellbeing. Results show that holding average parental years of schooling constant, both hypergamy and hypogamy predict lower levels of confidence and higher levels of depression than does parental homogamy. Children born to hypergamous parents where the mother has less than high school education are most vulnerable of all children. The negative effects of parental hypogamy are likely channelled through parent-child and interparental dynamics, as children from hypogamous families are more likely to experience issues in parent-child relationships, paternal drinking problems, and parental fights. [ABSTRACT FROM AUTHOR]

Studies have shown a tendency for educational elites to marry within the elite circle in China. However, little research explores how they find a partner and the platforms' roles in the process. We fill this gap by focusing on an online dating platform targeting alumni of elite universities. We interviewed the core staff of the platform to examine its operations. Through thematic analysis, we analyzed users' self-representations in their dating profiles and the platform's relatively high matching success rate. To achieve assortative matching for its elite users, the platform developed a large elite user base by setting university prestige as a dating threshold, hiring staff from elite universities, and providing profile editing and posting services. Users highlighted their privileged family backgrounds, elite university experiences, time-consuming hobbies, and preferences for a soulmate, as they aimed to attract similar partners. Our research reveals a new form of intra-clan marriage that has emerged with the massification of higher education. This homogamy, based on high levels of cultural capital, forms a social enclosure that may reinforce cultural inequalities beyond higher education. [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]

Parthenogenesis and interspecific mating are alternative reproductive strategies that species have evolved alternative strategies when the opportunity of sexual reproduction is hindered by the natural environment. However, it is still unclear how to make a choice between parthenogenesis and interspecific mating when females are unable to reproduce sexually with males of the same species.This study mainly investigated the reproductive behaviour of female termites in the absence of male termites of the same species. Here, reproductive behaviours of females Reticulitermes aculabialis (Ra♀) were observed when they encountered a male R. flaviceps (Rf♂) with the absence of male R. aculabialis(Ra♂).The results showed that Ra♀‐Rf♂ tandems were more prevalent and stable compared to Ra♀‐Ra♀ tandems. When a tandem inadvertently broke apart, the female R. aculabialis displayed longer pauses while waiting for male R. flaviceps, but shorter pauses when another female R. aculabialis was involved. Furthermore, there were mating behaviour between female R. aculabialis and males R. flaviceps, resulting in offspring produced in paired Ra♀‐Rf♂ colonies were hybridization between female R. aculabialis and male R. flaviceps.These results suggest that interspecific mating and recombination is an important aspect for the choice of reproduction strategy, which will provide new insights into the trade‐off between gene contribution rate and genetic diversity. [ABSTRACT FROM AUTHOR]

The way women construct their subjective social status has garnered significant attention. However, the roles of husbands and fathers in this process have been underexplored, with even less focus on how these roles have evolved across generations. This study aims to answer two important questions against the backdrop: First, which is the most dominant factor in shaping married women's subjective social status, their own objective class or those of their husband or father? Answers to this question reveal the impacts of assortative mating and intergenerational mobility. Second, how does the construction pattern change across birth cohorts? Cohort dynamics help reflect the evolution of gender roles and family values in China. Using pooled data from the Chinese General Social Survey in 2010–2017 and the diagonal reference model, our study finds that Chinese married women previously tended to construct their own social status based on the objective class of their husbands. However, this trend is reversed for younger cohorts. Father's objective class status carries roughly the same weight as women's own, but its impact becomes moderately stronger in younger cohorts. Taken together, the above findings reveal a unique pathway of family modernization in transitional China. Married women, although increasingly independent of their spouses, still remain closely connected with their natal families. [ABSTRACT FROM AUTHOR]

Recent social and economic trends in the United States, including increasing economic inequality, women's growing educational advantage, and the rise of online dating, have ambiguous implications for patterns of educational homogamy. In this research note, we examine changes in educational assortative mating in the United States over the last eight decades (1940 to 2020) using the U.S. decennial censuses and the American Community Survey, extending and expanding earlier work by Schwartz and Mare. We find that the rise in educational homogamy noted by Schwartz and Mare has not continued. Increases in educational homogamy stalled around 1990 and began reversing in the 2000s. We find a growing tendency for marriages to cross educational boundaries, but a college degree remains the strongest dividing line to intermarriage. A key trend explaining this new pattern is women's increasing tendency to marry men with less education than themselves. If not for this trend, homogamy would have continued increasing until the early 2010s. We also show substantial heterogeneity by race, ethnicity, and nativity and among same- versus different-sex couples. [ABSTRACT FROM AUTHOR]

Sensory drive can lead to the evolution of signals that are optimized to the environment in which they are perceived. However, when environmental conditions change, the interactions between signal, environment, and receiver may also shift, leading to the evolution of a new signal optimum or more categorical shifts in sexual signals (gains or losses). We evaluated how visual systems have evolved following a change in environment and male signal, and whether visual system divergence contributes to reproductive isolation between ancestral and derived types in red and black morphs of Pacific Northwest freshwater threespine stickleback. We found that opsin sequence was tuned to enhance the perceived contrast of black fish on a red-shifted light background, whereas opsin expression was not. Further, we found no evidence for homotypic preferences or assortative mating between colour morphs; males of both morphs were equally successful in no-choice mating contexts, perhaps because black males are more vigorous courters. Together, our results suggest that habitat transitions in black stickleback have led to a shift in sensory-drive dynamics with some aspects of the visual system and behaviour evolving in response to other factors (foraging or predation) or lagging behind the evolution of opsin sequences in red-shifted environments. [ABSTRACT FROM AUTHOR]

The worldwide expansion of female educational opportunities in recent decades has prompted demographers to assess the frequency with which women marry up (hypergamy) or down (hypogamy) with regard to education. A series of articles documented dramatic and nearly universal declines in hypergamy over time and across female educational advantage. However, this previous work investigated hypergamy only in the context of unequal educational pairings, excluding couples with equal levels of education (homogamy) from their analyses. Here, we argue that the prevalence of hypergamy should instead be assessed in relation to all marriages. We apply this approach to the case of Latin America, where women have made important gains in schooling relative to men. Using census microdata spanning 105 birth cohorts in 16 countries, we demonstrate that, rather than declining, hypergamy has increased in most countries over time and remains relatively stable across female educational advantage. Meanwhile, the prevalence of educational homogamy has declined considerably in most countries and across the axis of female educational advantage, an important trend that emerges only when homogamy is incorporated into the analysis. [ABSTRACT FROM AUTHOR]

This study examines within- and cross-country trends and differences in marital sorting by education in Europe. Unlike previous research on assortative mating, our study focuses on the outcomes of the partner search process. We investigate how variations in (a) structural opportunities (educational composition of potential partners) and (b) assortative mating (non-random matching by education) have shaped trends and differences in educational sorting outcomes. Using vital statistics data on all marriages contracted from 2000 to 2020 in Sweden, the Czech Republic, and Italy, we decompose trends and differences in educational sorting outcomes into these two components. Within countries, trends in educational homogamy and hypogamy have been stable or increasing while hypergamy has declined. However, the drivers of these trends varied across countries. For example, in Sweden, shifts in assortative mating and structural opportunities led to more marriages between equally educated spouses, while in Italy, the rise in homogamy stems solely from changes in assortative mating. Within each year, homogamy and heterogamy levels varied between countries. Our findings demonstrate that these cross-country differences can be primarily attributed to variations in assortative mating rather than in opportunity structures. This study adds to recent research studying the structural causes of trends in sorting outcomes. [ABSTRACT FROM AUTHOR]

Increased gender equality in the labor market and the home are both cited as stabilizers to income inequality between households, but shifts in the economic organization of families over the life course instead appear to amplify household income inequality. Using the case of Sweden, where men have taken longer parental leave in recent years and the age at parenthood continues to advance, we analyze between‐family income inequality for couples with a young child. Based on income data from population registers, we decompose how changes in family dynamics, pre‐ and postparenthood, contributed to income inequality in families with children between the years 1995 and 2018. Analyses show no evidence that assortative mating has increased and that a minor decline in inequality between couples over this 24‐year period resulted from two opposing trends: Dis‐equalizing changes related to women's postbirth income advancements were eclipsed by equalizing changes related to the postponement of parenthood. Postbirth income trends reveal how between‐family inequality increased through women's income development and decreased through men's. Our findings confirm the importance of family processes to household inequality and show the complex effects of both changes in the timing of parenthood and improved gender equality. [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]

Sexual selection plays a crucial role in modern evolutionary theory, offering valuable insight into evolutionary patterns and species diversity. Recently, a comprehensive definition of sexual selection has been proposed, defining it as any selection that arises from fitness differences associated with nonrandom success in the competition for access to gametes for fertilization. Previous research on discrete traits demonstrated that non-random mating can be effectively quantified using Jeffreys (or symmetrized Kullback-Leibler) divergence, capturing information acquired through mating influenced by mutual mating propensities instead of random occurrences. This novel theoretical framework allows for detecting and assessing the strength of sexual selection and assortative mating. In this study, we aim to achieve two primary objectives. Firstly, we demonstrate the seamless alignment of the previous theoretical development, rooted in information theory and mutual mating propensity, with the aforementioned definition of sexual selection. Secondly, we extend the theory to encompass quantitative traits. Our findings reveal that sexual selection and assortative mating can be quantified effectively for quantitative traits by measuring the information gain relative to the random mating pattern. The connection of the information indices of sexual selection with the classical measures of sexual selection is established. Additionally, if mating traits are normally distributed, the measure capturing the underlying information of assortative mating is a function of the square of the correlation coefficient, taking values within the non-negative real number set [0, +∞). It is worth noting that the same divergence measure captures information acquired through mating for both discrete and quantitative traits. This is interesting as it provides a common context and can help simplify the study of sexual selection patterns. [ABSTRACT FROM AUTHOR]

How sticky is wealth inequality across generations due to marital sorting? To analyze this question, we utilize a comprehensive Swiss dataset. Our findings highlight that marital sorting based on wealth is especially pronounced at the extremes of the wealth distribution, exacerbating wealth inequality. Simultaneously, we observe that the similarity in wealth between the parents of married partners is substantially less pronounced. Our findings suggest a more significant occurrence of marriages into "new money" than "old money". Consequently, our study shows that parental wealth has a limited role in contributing to the inequality stemming from marital choices. We present evidence that intergenerational social mobility plays a pivotal role in counteracting the potential intensification of wealth structures due to marriage. [ABSTRACT FROM AUTHOR]

Context: Cultural divergence refers to changes over time in behavioural traits. These cultural changes could have important implications for conservation planning, and impact the success of conservation efforts such as translocations. Aims: Here, we investigate the extent, and potential impacts, of cultural divergence in two isolated populations of the Floreana mockingbird (Mimus trifasciatus) on the Galápagos Islands. Methods: Using contemporary recordings of vocalisations we test for spatial vocal differentiation between mockingbird populations. Furthermore, we explore the potential drivers of change using morphological measurements and historical recordings of the species. Key results: We found evidence of spatial and temporal differentiation in vocalisations between the two populations of the Floreana mockingbird. We accurately classified over 75% of the birds to the correct populations based on multivariate measures of audio recordings using canonical analysis of principal coordinates (CAP). We also found significant differences in morphometrics between populations; specifically, beak depth was associated with frequency modulation, an acoustic measure that is significantly different between populations. Furthermore, we found evidence of change in the complexity of the vocalisations over a period of 57 years. Conclusions: Cultural divergence was found in the two remaining populations of this endangered species. Factors such as changes in morphology and cultural drift might have been influenced the change in vocalisation across time and populations. Implications: We highlight the importance of considering behavioural factors when planning reintroductions of endangered species where there is a need to minimise the risk of assortative mating so as to maximise genetic diversity. Cultural changes could have important implications for conservation planning, and impact the success of conservation efforts. We studied the cultural divergence between the last remaining population of the Floreana mockingbird. Anticipating potential challenges caused by cultural divergence will increase the likelihood of success of the species reintroduction to Floreana Island on the Galápagos Islands. [ABSTRACT FROM AUTHOR]

The strong negative correlation between divorce and a wide range of outcomes in terms of well-being, health, education and labour market performance has been well documented in the literature. Economic conditions have been found to affect marital stability. Shared gains from marriage also depend on spouses’ characteristics such as age, education, ethnicity and religious beliefs. This paper examines the relationship between these spousal characteristics and the probability of dissolution while taking into account business cycle fluctuations. Using data from the Panel Study of Income Dynamics 1968–2011 for the United States and employing a duration modelling strategy, findings reveal that differences in educational attainment and ethnicity between spouses increase the hazard of marital dissolution. However similarity in religious beliefs and ethnicity reduce the risk of divorce. A period of economic growth improves marital stability. However, ethnic differences are a significant predictor of marital division, even in times of economic prosperity.

Recent decades have seen major changes in the educational profiles of the populations of Western industrialised countries, notably a sharp rise in educational attainment and a reversal of the gender gap in education. These trends are likely to have affected patterns of educational assortative mating and its consequences. In this editorial, we first review the empirical evidence on educational assortative mating patterns over the last two decades. Specifically, we examine whether educational homogamy has increased among the highly educated, whether women are now less likely to marry upward across cohorts, and whether the rates of relative educational homogamy in populations have increased. We also examine the factors that explain trends and cross-country differences in educational homogamy. Second, we review the consequences of educational homogamy for several important social outcomes, in particular partnership stability and union dissolution, fertility, and children’s educational attainment. Is educational homogamy increasingly affecting these outcomes, and if so, in what ways and why? Third, we identify research gaps regarding educational assortative mating and its consequences. The six empirical studies in this special issue attempt to fill some of these gaps. We briefly outline these studies and their main findings and point to implications for future research. * This editorial has been peer reviewed.

The Journal of Avian Biology (JAB) publishes high-quality research on birds' ecology, evolution, and behavior from around the world. To provide a more nimble format for publishing overviews in avian biology, JAB introduced the 'mini-review' article category in 2022. The journal also established the 'JAB review award' to recognize exceptional mini-review manuscripts from early career researchers, with winners receiving a 1000€ honorarium. The competition aims to highlight new developments in avian research and encourage submissions from underrepresented groups and geographic areas. [Extracted from the article]

Abstract Background According to the most recent U.S. CDC surveillance data, the rise in prevalence of childhood autism spectrum disorder among minority children has begun to outpace that of non-Hispanic white children. Since prior research has identified possible differences in the extent of mate selection for autistic traits across families of different ethnicity, this study examined variation in autism related traits in contemporaneous, epidemiologically ascertained samples of spousal pairs representing Hispanic and non-Hispanic white populations. The purpose was to determine whether discrepancies by ethnicity could contribute to differential increases in prevalence in the current generation of young children. Methods Birth records were used to identify all twin pairs born between 2011 and 2013 in California and Missouri. Families were selected at random from pools of English-speaking Hispanic families in California and Non-Hispanic White families in Missouri. Autistic trait data of parents was obtained using the Adult Report Form of the Social Responsiveness Scale (SRS-2). Results We did not identify a statistically significant difference in the degree of mate selection for autism related traits between Hispanic and non-Hispanic white spousal pairs. However, the degree of spousal correlation observed in this recent cohort was pronounced (on the order of ICC 0.45) and exceeded that typically reported in prior research (on the order of 0.30), surpassing also widely reported estimates for sibling correlation (also on the order of 0.30). Limitations The sample did not allow for a direct appraisal of change in the magnitude of spousal correlation over time and the ascertainments of trait burden were derived from spouse report. Conclusion Across two epidemiologically ascertained samples of spousal pairs representing Hispanic and non-Hispanic white families across two U.S. states (respectively, California and Missouri), the extent of autism-related trait co-variation for parents of the current generation of young children is substantial and exceeds correlations typically observed for siblings. Given the heritability of these traits and their relation to autism risk, societal trends in the degree of mate selection for these traits should be considered as possible contributors to subtle increases in the incidence of autism over time and across generations.

Abstract Background Positive assortative mating (AM) in several neuropsychiatric traits, including autism, has been noted. However, it is unknown whether the pattern of AM is different in phenotypically defined autism subgroups [e.g., autism with and without intellectually disability (ID)]. It is also unclear what proportion of the phenotypic AM can be explained by the genetic similarity between parents of children with an autism diagnosis, and the consequences of AM on the genetic structure of the population. Methods To address these questions, we analyzed two family-based autism collections: the Simons Foundation Powering Autism Research for Knowledge (SPARK) (1575 families) and the Simons Simplex Collection (SSC) (2283 families). Results We found a similar degree of phenotypic and ancestry-related AM in parents of children with an autism diagnosis regardless of the presence of ID. We did not find evidence of AM for autism based on autism polygenic scores (PGS) (at a threshold of |r|> 0.1). The adjustment of ancestry-related AM or autism PGS accounted for only 0.3–4% of the fractional change in the estimate of the phenotypic AM. The ancestry-related AM introduced higher long-range linkage disequilibrium (LD) between single nucleotide polymorphisms (SNPs) on different chromosomes that are highly ancestry-informative compared to SNPs that are less ancestry-informative (D2 on the order of 1 × 10−5). Limitations We only analyzed participants of European ancestry, limiting the generalizability of our results to individuals of non-European ancestry. SPARK and SSC were both multicenter studies. Therefore, there could be ancestry-related AM in SPARK and SSC due to geographic stratification. The study participants from each site were unknown, so we were unable to evaluate for geographic stratification. Conclusions This study showed similar patterns of AM in autism with and without ID, and demonstrated that the common genetic influences of autism are likely relevant to both autism groups. The adjustment of ancestry-related AM and autism PGS accounted for

Background: According to the most recent U.S. CDC surveillance data, the rise in prevalence of childhood autism spectrum disorder among minority children has begun to outpace that of non-Hispanic white children. Since prior research has identified possible differences in the extent of mate selection for autistic traits across families of different ethnicity, this study examined variation in autism related traits in contemporaneous, epidemiologically ascertained samples of spousal pairs representing Hispanic and non-Hispanic white populations. The purpose was to determine whether discrepancies by ethnicity could contribute to differential increases in prevalence in the current generation of young children. Methods: Birth records were used to identify all twin pairs born between 2011 and 2013 in California and Missouri. Families were selected at random from pools of English-speaking Hispanic families in California and Non-Hispanic White families in Missouri. Autistic trait data of parents was obtained using the Adult Report Form of the Social Responsiveness Scale (SRS-2). Results: We did not identify a statistically significant difference in the degree of mate selection for autism related traits between Hispanic and non-Hispanic white spousal pairs. However, the degree of spousal correlation observed in this recent cohort was pronounced (on the order of ICC 0.45) and exceeded that typically reported in prior research (on the order of 0.30), surpassing also widely reported estimates for sibling correlation (also on the order of 0.30). Limitations: The sample did not allow for a direct appraisal of change in the magnitude of spousal correlation over time and the ascertainments of trait burden were derived from spouse report. Conclusion: Across two epidemiologically ascertained samples of spousal pairs representing Hispanic and non-Hispanic white families across two U.S. states (respectively, California and Missouri), the extent of autism-related trait co-variation for parents of the current generation of young children is substantial and exceeds correlations typically observed for siblings. Given the heritability of these traits and their relation to autism risk, societal trends in the degree of mate selection for these traits should be considered as possible contributors to subtle increases in the incidence of autism over time and across generations. [ABSTRACT FROM AUTHOR]

The fixation index, FIS, has been a staple measure to detect selection, or departures from random mating in populations. However, current Next Generation Sequencing (NGS) cannot easily estimate FIS, in multi‐locus gene families that contain multiple loci having similar or identical arrays of variant sequences of ≥1 kilobase (kb), which differ at multiple positions. In these families, high‐quality short‐read NGS data typically identify variants, but not the genomic location, which is required to calculate FIS (based on locus‐specific observed and expected heterozygosity). Thus, to assess assortative mating, or selection on heterozygotes, from NGS of multi‐locus gene families, we need a method that does not require knowledge of which variants are alleles at which locus in the genome. We developed such a method. Like FIS, our novel measure, 1HIS, is based on the principle that positive assortative mating, or selection against heterozygotes, and some other processes reduce within‐individual variability relative to the population. We demonstrate high accuracy of 1HIS on a wide range of simulated scenarios and two datasets from natural populations of penguins and dolphins. 1HIS is important because multi‐locus gene families are often involved in assortative mating or selection on heterozygotes. 1HIS is particularly useful for multi‐locus gene families, such as toll‐like receptors, the major histocompatibility complex in animals, homeobox genes in fungi and self‐incompatibility genes in plants. [ABSTRACT FROM AUTHOR]

Background: To date, the magnitude of association and the quality of evidence for cognitive decline (mild cognitive impairment, Alzheimer's disease, and dementia) in couples and risk factors for outcomes have not been reviewed and analyzed systematically. Objective: The aim of this study was to investigate the concordance of cognitive impairment in unrelated spouses and to qualitatively describe potential risk factors. Methods: Eight databases were searched from inception to October 20, 2023. Eligible studies were independently screened and assessed for quality. Statistical analysis was conducted using Stata 15.1 software. The study was preregistered with PROSPERO (CRD42023488024). Results: Eleven studies involving couples were included, with moderate to high evidence quality. Compared to controls, spouses of individuals with cognitive impairment had lower cognitive scores (Cohen's d: 0.18-0.62) and higher risk of cognitive decline (OR = 1.42, 95% CI: 1.15–1.76). The consistency of cognitive impairment between spouses was attributed to three theories: 1) the impact of caregiving stress experienced by the spouse; 2) assortative mating, which suggests that individuals select partners with similar characteristics; and 3) the influence of shared living environments and lifestyles. Conclusions: The cognitive status of one spouse can affect the cognitive function of the other spouse. It is important to consider shared lifestyle, environmental, and psychobehavioral factors, as they may contribute to the risk of cognitive decline by couples. Identifying these factors can inform the development of targeted recommendations for interventions and preventive measures. [ABSTRACT FROM AUTHOR]

While racial assortative mating and interracial unions have been a central interest in the study of race relations and family demography since the early twentieth century, there have been marked changes in the social contexts in which these processes have taken place in recent decades. This review article examines three important shifts: (a) the rise of population diversity and its impact on traditional views of racial integration, (b) the changing institution of marriage in American life, and (c) the increasing centrality of technology. We discuss how these societal shifts have challenged traditional understandings of preferences, opportunities, and intermediaries in the mate selection process, as well as new opportunities for interracial intimacy that these changes have introduced. We conclude with a discussion on conceptual issues and promising future research directions. [ABSTRACT FROM AUTHOR]

In this article, we analytically model marital sorting, intergenerational transfers, and inequality in a household optimization model with uncertainty. We modify and apply a 'sorting, reverse sorting' numerical approach by Demirtas in the context of marriage market mating, illustrating the robustness of our analytical results. We show that the parameters of the family production function play an important role in driving the path of an economy's inequality. One finding is that, under assortative mating, factor shares in the family production function positively affect inequality, while under disassortative mating, the relationship between the factor shares and inequality is U-shaped. This and other results that we obtain can stimulate further empirical research, holding potentially important policy implications. [ABSTRACT FROM AUTHOR]

Background: Positive assortative mating (AM) in several neuropsychiatric traits, including autism, has been noted. However, it is unknown whether the pattern of AM is different in phenotypically defined autism subgroups [e.g., autism with and without intellectually disability (ID)]. It is also unclear what proportion of the phenotypic AM can be explained by the genetic similarity between parents of children with an autism diagnosis, and the consequences of AM on the genetic structure of the population. Methods: To address these questions, we analyzed two family-based autism collections: the Simons Foundation Powering Autism Research for Knowledge (SPARK) (1575 families) and the Simons Simplex Collection (SSC) (2283 families). Results: We found a similar degree of phenotypic and ancestry-related AM in parents of children with an autism diagnosis regardless of the presence of ID. We did not find evidence of AM for autism based on autism polygenic scores (PGS) (at a threshold of |r|> 0.1). The adjustment of ancestry-related AM or autism PGS accounted for only 0.3–4% of the fractional change in the estimate of the phenotypic AM. The ancestry-related AM introduced higher long-range linkage disequilibrium (LD) between single nucleotide polymorphisms (SNPs) on different chromosomes that are highly ancestry-informative compared to SNPs that are less ancestry-informative (D2 on the order of 1 × 10−5). Limitations: We only analyzed participants of European ancestry, limiting the generalizability of our results to individuals of non-European ancestry. SPARK and SSC were both multicenter studies. Therefore, there could be ancestry-related AM in SPARK and SSC due to geographic stratification. The study participants from each site were unknown, so we were unable to evaluate for geographic stratification. Conclusions: This study showed similar patterns of AM in autism with and without ID, and demonstrated that the common genetic influences of autism are likely relevant to both autism groups. The adjustment of ancestry-related AM and autism PGS accounted for < 5% of the fractional change in the estimate of the phenotypic AM. Future studies are needed to evaluate if the small increase of long-range LD induced by ancestry-related AM has impact on the downstream analysis. [ABSTRACT FROM AUTHOR]

Acoustic differentiation in bird vocalisations is a key process for speciation. Calls have received little attention compared to songs, but their simplicity facilitates analysis using mathematical, non-biased, tools, as they can be described by means of very basic variables. Here, we combined PERMANOVA and machine learning techniques to analyse the differentiation in the contact calls of the closely related Dartford (Curruca undata), Marmora's (C. sarda) and Balearic (C. balearica) warblers (formerly in the genus Sylvia). The calls of the three species differed clearly, consistent with phylogenetic reconstructions based on DNA sequences. In C. sarda, significant call differences were observed between the population wintering in Tunisia (migratory) and those of Sardinia and Corsica (mainly sedentary). Such divergence could be favoured by assortative mating of migrant and resident individuals, working as a matching mechanism for reproductive isolation in sympatry. In contrast, there was no clear separation between the accepted subspecies of C. undata. We found, however, significant differences between the Atlantic and Mediterranean biogeographical regions in this species. The divergences detected within C. undata and C. sarda deserve further investigation, using additional traits to elucidate the phylogenetic status of these groups, as well as the factors driving their diversification. [ABSTRACT FROM AUTHOR]

Background: Hyperactivity and inattention, the symptoms of ADHD, are marked by high levels of heritability and intergenerational transmission. Two distinct pathways of genetic intergenerational transmission are distinguished: direct genetic transmission when parental genetic variants are passed to the child's genome and genetic nurture when the parental genetic background contributes to the child's outcomes through rearing environment. This study assessed genetic contributions to hyperactivity and inattention in childhood through these transmission pathways. Methods: The sample included 415 families from the Quebec Newborn Twin Study. Twins' hyperactivity and inattention were assessed in early childhood by parents and in primary school by teachers. The polygenic scores for ADHD (ADHD‐PGS) and educational attainment (EA‐PGS) were computed from twins' and parents' genotypes. A model of intergenerational transmission was developed to estimate (1) the contributions of parents' and children's PGS to the twins' ADHD symptoms and (2) whether these variances were explained by genetic transmission and/or genetic nurture. Results: ADHD‐PGS explained up to 1.6% of the variance of hyperactivity and inattention in early childhood and primary school. EA‐PGS predicted ADHD symptoms at both ages, explaining up to 1.6% of the variance in early childhood and up to 5.5% in primary school. Genetic transmission was the only significant transmission pathway of both PGS. The genetic nurture channeled through EA‐PGS explained up to 3.2% of the variance of inattention in primary school but this association was non‐significant. Conclusions: Genetic propensities to ADHD and education predicted ADHD symptoms in childhood, especially in primary school. Its intergenerational transmission was driven primarily by genetic variants passed to the child, rather than by environmentally mediated parental genetic effects. The model developed in this study can be leveraged in future research to investigate genetic transmission and genetic nurture while accounting for parental assortative mating. [ABSTRACT FROM AUTHOR]

The evolution of behavioral isolation is often the first step toward speciation. While past studies show that behavioral isolation will sometimes evolve as a by-product of divergent ecological selection, we lack a more nuanced understanding of factors that may promote or hamper its evolution. The environment in which mating occurs may be important in mediating whether behavioral isolation evolves for two reasons. Ecological speciation could occur as a direct outcome of different sexual interactions being favored in different mating environments. Alternatively, mating environments may vary in the constraint they impose on traits underlying mating interactions, such that populations evolving in a "constraining" mating environment would be less likely to evolve behavioral isolation than populations evolving in a less constraining mating environment. In the latter, mating environment is not the direct cause of behavioral isolation but rather permits its evolution only if other drivers are present. We test these ideas with a set of 28 experimental fly populations, each of which evolved under one of two mating environments and one of two larval environments. Counter to the prediction of ecological speciation by mating environment, behavioral isolation was not maximal between populations evolved in different mating environments. Nonetheless, mating environment was an important factor as behavioral isolation evolved among populations from one mating environment but not among populations from the other. Though one mating environment was conducive to the evolution of behavioral isolation, it was not sufficient: assortative mating only evolved between populations adapting to different-larval environments within that mating environment, indicating a role for ecological speciation. Intriguingly, the mating environment that promoted behavioral isolation is characterized by less sexual conflict compared to the other mating environment. Our results suggest that mating environments play a key role in mediating ecological speciation via other axes of divergent selection. [ABSTRACT FROM AUTHOR]

We study changes in educational homogamy in the US and four European countries over the decade covering the Great Recession. The marital preferences identified point to the widening of the social gap between different educational groups since these preferences have increased the inclination of the individuals to match with others of similar educational traits in all five countries. We obtain this finding with an aggregate measure characterizing revealed preferences of individuals in relationship. We apply a novel approach for validating our finding: we compare our aggregate measure with dating data informative about the reservation points not only of those people who will be in a couple, but also those who will remain single. Finally, we challenge a commonly held view: we argue that marital preferences should not be blamed for the documented increase of the social gap since preferences are not exogenous, but are shaped by changes in the employment prospects of the potential partners. [ABSTRACT FROM AUTHOR]

Very recently, an interesting phenomenon was described in the common vole; vole parents with similar locomotor ability produced significantly larger litters. Positive assortative mating is a tendency to prefer individuals with similar phenotypes. We tested whether this also applies to smell similarity. Odour preference was tested in a T-maze, where each female was presented with two male odours, i.e. shavings together with feces and urine from home boxes. After female preference was established, the female was either paired with a preferred male (chosen) or paired with a non-preferred male (opposite choice). For analysis of the relationship to odour preference, genotyping of major histocompatibility complex (MHC) Class II DRB was done using amplicon sequencing. In the set of 45 individuals from two populations, we recovered 38 nucleotide haplotypes (alleles). Similarity of alleles in parent pairs according to the indexes of Sørensen–Dice (S–D) and Jaccard were calculated. Values of these indexes in parental pairs with preferred males were significantly higher (more similar) than in not preferred. The number of offspring in parental pairs with preferred males were significantly higher than in not preferred males. However, there is no correlation between the mentioned indexes and the number of offspring. The relationship between the success of reproduction and alleles is not clear-cut, this may be influenced by the measure of similarity we used, or by something that we could not detect. [ABSTRACT FROM AUTHOR]

With the increasing education of women in developing countries, educational assortative mating has become a significant aspect in the marriage market, with educational assortative mating patterns likely to be dependent on marriage timing. Using pooled data from three recent waves of the Cameroon Demographic and Health Surveys, the paper investigates the effect of marriage timing on educational assortative mating patterns in Cameroon. To achieve the objective, the study employed the Cox proportional hazard model and a control function version of multinomial Probit. Results show that delaying marriage is expected to decrease the likelihood of women engaging in low educationally homogamous marriages while increasing the probability of women entering high educationally homogamous and hypogamous marriages. Findings further depicted that over the period 2004–2018, the likelihood of women engaging in low educationally homogamous marriages decreased meanwhile the likelihood of women considering high educationally homogamous marriages and hypogamous marriages increased. The implications of these findings are in tandem with the wisdom that, programs encouraging the girl child to delay early marriages and stay longer in school can help women engage in high educationally homogamous marriages, empower women and thus improves their socioeconomic status. [ABSTRACT FROM AUTHOR]

The paradox between the ubiquity of polyploid lineages in plants and the early obstacles to the establishment of polyploids is a long‐studied yet unresolved question in evolutionary biology. It is assumed that to successfully persist after emergence, newly formed polyploids need to display certain fitness advantages and show a certain extent of reproductive isolation with their diploid progenitors. In this study, we tested whether immediate floral changes following polyploidization can improve pollinator visitation and enable pollinator preference leading to assortative mating, i.e. build a premating reproductive barrier between diploids and polyploids. For this purpose, we generated synthetic tetraploids of Arabidopsis arenosa and measured insect visitor behavior on diploids and synthetic tetraploids. We found that the increased floral size that accompanied polyploidization did not lead to a measurable increase in visitor preference, with insects visiting diploid and tetraploid plants at equal frequency. Despite this observation, tetraploids set more fruits than diploids, suggesting a positive impact of polyploidization on pollen transfer via other means. In addition, polyploidization did not lead to assortative mating but instead promoted interploidy pollen exchange, since visitors preferentially switched between cytotypes rather than preferring one. Consistent with this switching behavior, most of the progeny from tetraploid plants were triploid. Our data suggest that polyploidization has an immediate impact on mating in plants, but in a more complex way than has been assumed previously. [ABSTRACT FROM AUTHOR]

The strategic location of North Africa has led to cultural and demographic shifts, shaping its genetic structure. Historical migrations brought different genetic components that are evident in present-day North African genomes, along with autochthonous components. The Imazighen (plural of Amazigh) are believed to be the descendants of autochthonous North Africans and speak various Amazigh languages, which belong to the Afro-Asiatic language family. However, the arrival of different human groups, especially during the Arab conquest, caused cultural and linguistic changes in local populations, increasing their heterogeneity. We aim to characterize the genetic structure of the region, using the largest Amazigh dataset to date and other reference samples. Our findings indicate microgeographical genetic heterogeneity among Amazigh populations, modeled by various admixture waves and different effective population sizes. A first admixture wave is detected group-wide around the twelfth century, whereas a second wave appears in some Amazigh groups around the nineteenth century. These events involved populations with higher genetic ancestry from south of the Sahara compared to the current North Africans. A plausible explanation would be the historical trans-Saharan slave trade, which lasted from the Roman times to the nineteenth century. Furthermore, our investigation shows that assortative mating in North Africa has been rare. [ABSTRACT FROM AUTHOR]

The reversal of the gender gap in education has transformed traditional patterns of assortative mating, increasing the number of hypogamous couples. This change has been particularly intense in the case of Spain, a country of great interest due to the ambivalence of strong support for egalitarian attitudes and high proportion of traditional couples. Using quarterly microdata from the Spanish Labour Force Survey, applying generalised ordered-logit models, this research reveals that educational hypogamy increases the probability of occupational hypogamy. This association is consistent with the use of different occupational classifications and levels of disaggregation. But there are some factors that limit the transmission of women's educational advantages to their occupational levels, mainly gender differences in access to the labour market and an uneven distribution of professional achievements by sex. The findings obtained underline the relevance of using different measures as well as different theoretical approaches to explain seemingly contradictory couple equilibria. [ABSTRACT FROM AUTHOR]

In this study, we explore how educational differences in demographic behavior – in particular, mating patterns and fertility – mediate the intergenerational reproduction of educational inequality in twelve European countries. Although this research interest itself is not new, we contribute to this debate by adopting a prospective approach and scaling it to include multiple countries and cohorts. To this end, we leverage a series of complementary datasets and the inferential method developed by Song and Mare (2015) and advanced by Skopek and Leopold (2020) to estimate the components of a stylized educational reproduction model. We then employ a simple decomposition analysis to quantify the contributions of different pathways to prospective educational reproduction rates across educational backgrounds and explore the differences across cohorts and countries. We report several findings. Most notably, (1) the intergenerational reproduction of educational inequality persists in all twelve countries and is barely offset by small (and declining) negative educational gradients in fertility, (2) educational differences in selection into partnership are small and do not account for much inequality, and (3) the role of assortative mating, where present, is ambiguous because it both reinforces inequality via its effects on resources within the family and offsets it via its effects on fertility. * This article belongs to a special issue on “Changes in Educational Homogamy and Its Consequences”.