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En stor del av dem som bildar par i Sverige har idag träffats på olika online-dejtingplattformar. Tidigare forskning har visat att kvinnor är mer selektiva i val av partner. Detta kan göra att män riskerar att bli bortvalda i dessa sammanhang, vilket kan medföra negativa konsekvenser för den enskilda individen och samhället i stort. Syftet med denna kvalitativa studie är att undersöka heterosexuella kvinnors preferenser och resonemang om mäns profiler inom online-dejting, med fokus på vad som får dem att välja en profil. För att besvara syftet ställs följande frågeställningar: “Vad anser heterosexuella kvinnor att en online-dejtingprofil skall innehålla för att de skall välja den?” och “Hur resonerar heterosexuella kvinnor när de väljer en online-dejtingprofil?". Semistrukturerade intervjuer har utförts med nio heterosexuella kvinnor mellan 22 och 30 år och materialet har därefter analyserats tematiskt. Studien har haft en abduktiv ansats och data diskuteras delvis utifrån teorin om assortative mating. Studien visade att kvinnor initialt resonerade kring profilens uppfattade positiva attribut, därefter sökte de efter ledtrådar i profilen om mannens egenskaper och slutligen visualiserade de sig att dejta mannen i verkligheten. Studiens resultat visade visst stöd för assortative mating då liknande värderingar var något många av respondenterna uppvisade preferenser för. Resultatet visade också att respondenterna konsekvent sökte efter ledtrådar i mannens online-dejtingprofil, ett sätt för dem att hantera den digitala miljön, med begränsad information. Studiens resultat diskuteras delvis utifrån ett perspektiv om kulturella skillnader, då assortative mating är utformad i en amerikansk kontext.

Colour polymorphisms have long served as model systems in evolutionary studies and continue to inform about processes involved in the origin and dynamics of biodiversity. Modern sequencing tools allow for evaluating whether phenotypic differences between morphs reflect genetic differentiation rather than developmental plasticity, and for investigating whether polymorphisms represent intermediate stages of diversification towards speciation. We investigated phenotypic and genetic differentiation between two colour morphs of the butterfly Fabriciana adippe using a combination of ddRAD-sequencing and comparisons of body size, colour patterns and optical properties of bright wing spots. The silvery-spotted adippe form had larger and darker wings and reflected UV light, while the yellow cleodoxa form displayed more green scales and reflected very little UV, showcasing that they constitute distinct and alternative integrated phenotypes. Genomic analyses revealed genetic structuring according to source population, and to colour morph, suggesting that the phenotypic differentiation reflects evolutionary modifications. We report 17 outlier loci associated with colour morph, including ultraviolet-sensitive visual pigment (UVRh1), which is associated with intraspecific communication and mate choice in butterflies. Together with the demonstration that the wings of the adippe (but essentially not the cleodoxa) morph reflect UV light, that UV reflectance is higher in females than males and that morphs differ in wing size, this suggests that these colour morphs might represent genetically integrated phenotypes, possibly adapted to different microhabitats. We propose that non-random mating might contribute to the differentiation and maintenance of the polymorphism.

Colour polymorphisms have long served as model systems in evolutionary studies and continue to inform about processes involved in the origin and dynamics of biodiversity. Modern sequencing tools allow for evaluating whether phenotypic differences between morphs reflect genetic differentiation rather than developmental plasticity, and for investigating whether polymorphisms represent intermediate stages of diversification towards speciation. We investigated phenotypic and genetic differentiation between two colour morphs of the butterfly Fabriciana adippe using a combination of ddRAD-sequencing and comparisons of body size, colour patterns and optical properties of bright wing spots. The silvery-spotted adippe form had larger and darker wings and reflected UV light, while the yellow cleodoxa form displayed more green scales and reflected very little UV, showcasing that they constitute distinct and alternative integrated phenotypes. Genomic analyses revealed genetic structuring according to source population, and to colour morph, suggesting that the phenotypic differentiation reflects evolutionary modifications. We report 17 outlier loci associated with colour morph, including ultraviolet-sensitive visual pigment (UVRh1), which is associated with intraspecific communication and mate choice in butterflies. Together with the demonstration that the wings of the adippe (but essentially not the cleodoxa) morph reflect UV light, that UV reflectance is higher in females than males and that morphs differ in wing size, this suggests that these colour morphs might represent genetically integrated phenotypes, possibly adapted to different microhabitats. We propose that non-random mating might contribute to the differentiation and maintenance of the polymorphism.

Colour polymorphisms have long served as model systems in evolutionary studies and continue to inform about processes involved in the origin and dynamics of biodiversity. Modern sequencing tools allow for evaluating whether phenotypic differences between morphs reflect genetic differentiation rather than developmental plasticity, and for investigating whether polymorphisms represent intermediate stages of diversification towards speciation. We investigated phenotypic and genetic differentiation between two colour morphs of the butterfly Fabriciana adippe using a combination of ddRAD-sequencing and comparisons of body size, colour patterns and optical properties of bright wing spots. The silvery-spotted adippe form had larger and darker wings and reflected UV light, while the yellow cleodoxa form displayed more green scales and reflected very little UV, showcasing that they constitute distinct and alternative integrated phenotypes. Genomic analyses revealed genetic structuring according to source population, and to colour morph, suggesting that the phenotypic differentiation reflects evolutionary modifications. We report 17 outlier loci associated with colour morph, including ultraviolet-sensitive visual pigment (UVRh1), which is associated with intraspecific communication and mate choice in butterflies. Together with the demonstration that the wings of the adippe (but essentially not the cleodoxa) morph reflect UV light, that UV reflectance is higher in females than males and that morphs differ in wing size, this suggests that these colour morphs might represent genetically integrated phenotypes, possibly adapted to different microhabitats. We propose that non-random mating might contribute to the differentiation and maintenance of the polymorphism.

Colour polymorphisms have long served as model systems in evolutionary studies and continue to inform about processes involved in the origin and dynamics of biodiversity. Modern sequencing tools allow for evaluating whether phenotypic differences between morphs reflect genetic differentiation rather than developmental plasticity, and for investigating whether polymorphisms represent intermediate stages of diversification towards speciation. We investigated phenotypic and genetic differentiation between two colour morphs of the butterfly Fabriciana adippe using a combination of ddRAD-sequencing and comparisons of body size, colour patterns and optical properties of bright wing spots. The silvery-spotted adippe form had larger and darker wings and reflected UV light, while the yellow cleodoxa form displayed more green scales and reflected very little UV, showcasing that they constitute distinct and alternative integrated phenotypes. Genomic analyses revealed genetic structuring according to source population, and to colour morph, suggesting that the phenotypic differentiation reflects evolutionary modifications. We report 17 outlier loci associated with colour morph, including ultraviolet-sensitive visual pigment (UVRh1), which is associated with intraspecific communication and mate choice in butterflies. Together with the demonstration that the wings of the adippe (but essentially not the cleodoxa) morph reflect UV light, that UV reflectance is higher in females than males and that morphs differ in wing size, this suggests that these colour morphs might represent genetically integrated phenotypes, possibly adapted to different microhabitats. We propose that non-random mating might contribute to the differentiation and maintenance of the polymorphism.

Colour polymorphisms have long served as model systems in evolutionary studies and continue to inform about processes involved in the origin and dynamics of biodiversity. Modern sequencing tools allow for evaluating whether phenotypic differences between morphs reflect genetic differentiation rather than developmental plasticity, and for investigating whether polymorphisms represent intermediate stages of diversification towards speciation. We investigated phenotypic and genetic differentiation between two colour morphs of the butterfly Fabriciana adippe using a combination of ddRAD-sequencing and comparisons of body size, colour patterns and optical properties of bright wing spots. The silvery-spotted adippe form had larger and darker wings and reflected UV light, while the yellow cleodoxa form displayed more green scales and reflected very little UV, showcasing that they constitute distinct and alternative integrated phenotypes. Genomic analyses revealed genetic structuring according to source population, and to colour morph, suggesting that the phenotypic differentiation reflects evolutionary modifications. We report 17 outlier loci associated with colour morph, including ultraviolet-sensitive visual pigment (UVRh1), which is associated with intraspecific communication and mate choice in butterflies. Together with the demonstration that the wings of the adippe (but essentially not the cleodoxa) morph reflect UV light, that UV reflectance is higher in females than males and that morphs differ in wing size, this suggests that these colour morphs might represent genetically integrated phenotypes, possibly adapted to different microhabitats. We propose that non-random mating might contribute to the differentiation and maintenance of the polymorphism.

En stor del av dem som bildar par i Sverige har idag träffats på olika online-dejtingplattformar. Tidigare forskning har visat att kvinnor är mer selektiva i val av partner. Detta kan göra att män riskerar att bli bortvalda i dessa sammanhang, vilket kan medföra negativa konsekvenser för den enskilda individen och samhället i stort. Syftet med denna kvalitativa studie är att undersöka heterosexuella kvinnors preferenser och resonemang om mäns profiler inom online-dejting, med fokus på vad som får dem att välja en profil. För att besvara syftet ställs följande frågeställningar: “Vad anser heterosexuella kvinnor att en online-dejtingprofil skall innehålla för att de skall välja den?” och “Hur resonerar heterosexuella kvinnor när de väljer en online-dejtingprofil?". Semistrukturerade intervjuer har utförts med nio heterosexuella kvinnor mellan 22 och 30 år och materialet har därefter analyserats tematiskt. Studien har haft en abduktiv ansats och data diskuteras delvis utifrån teorin om assortative mating. Studien visade att kvinnor initialt resonerade kring profilens uppfattade positiva attribut, därefter sökte de efter ledtrådar i profilen om mannens egenskaper och slutligen visualiserade de sig att dejta mannen i verkligheten. Studiens resultat visade visst stöd för assortative mating då liknande värderingar var något många av respondenterna uppvisade preferenser för. Resultatet visade också att respondenterna konsekvent sökte efter ledtrådar i mannens online-dejtingprofil, ett sätt för dem att hantera den digitala miljön, med begränsad information. Studiens resultat diskuteras delvis utifrån ett perspektiv om kulturella skillnader, då assortative mating är utformad i en amerikansk kontext.

Colour polymorphisms have long served as model systems in evolutionary studies and continue to inform about processes involved in the origin and dynamics of biodiversity. Modern sequencing tools allow for evaluating whether phenotypic differences between morphs reflect genetic differentiation rather than developmental plasticity, and for investigating whether polymorphisms represent intermediate stages of diversification towards speciation. We investigated phenotypic and genetic differentiation between two colour morphs of the butterfly Fabriciana adippe using a combination of ddRAD-sequencing and comparisons of body size, colour patterns and optical properties of bright wing spots. The silvery-spotted adippe form had larger and darker wings and reflected UV light, while the yellow cleodoxa form displayed more green scales and reflected very little UV, showcasing that they constitute distinct and alternative integrated phenotypes. Genomic analyses revealed genetic structuring according to source population, and to colour morph, suggesting that the phenotypic differentiation reflects evolutionary modifications. We report 17 outlier loci associated with colour morph, including ultraviolet-sensitive visual pigment (UVRh1), which is associated with intraspecific communication and mate choice in butterflies. Together with the demonstration that the wings of the adippe (but essentially not the cleodoxa) morph reflect UV light, that UV reflectance is higher in females than males and that morphs differ in wing size, this suggests that these colour morphs might represent genetically integrated phenotypes, possibly adapted to different microhabitats. We propose that non-random mating might contribute to the differentiation and maintenance of the polymorphism.

Recent research into intergenerational social mobility has examined the association between the socioeconomic position of grandparents (G1) and their grandchildren (G3), but it remains unclear why G1-G3 associations arise. Prevailing explanations focus on whether grandparents have a true direct influence on their grandchildren or an indirect one via omitted parental characteristics. We argue that there may be other important indirect pathways of multigenerational persistence: grandparents can transmit resources via uncles and aunts, and they can encourage assortative mating in the middle generation, which also increases the resources available to their grandchildren. We examine these indirect pathways by studying the status attainment of 176,678 Dutch men for the period 1857 to 1922 using marriage certificates. Results show that G3ʹs status was substantially associated with uncles’ status and that assortative mating based on social origin was strong. Accounting for these associations reduces much of the G1-G3 association. We therefore conclude that multigenerational persistence arose hardly because grandfathers had a direct influence but rather because grandfathers were important in more indirect ways.

Background: Both maternal and, separately, paternal mental illness are associated with diminished academic attainment among children. However, the differential impacts of diagnostic type and degree of parental burden (e.g. one v. both parents affected) on these functional outcomes are unknown. Methods: Using the Swedish national patient (NPR) and multi-generation (MGR) registers, 2 226 451 children (1 290 157 parental pairs), born 1 January 1973-31 December 1997, were followed through 31 December 2013. Diagnostic status of all cohort members was defined for eleven psychiatric disorders, and families classed by exposure: (1) parents affected with any disorder, (2) parents affected with a disorder group (e.g. neuropsychiatric disorders), and (3) parents affected with a specific disorder (e.g. ADHD). Pairs were further defined as 'unaffected,' 'single-affected,', or 'dual-affected.' Among offspring, the study evaluated fulfillment of four academic milestones, from compulsory (primary) school through University (college). Sensitivity analyses considered the impact of child's own mental health, as well as parental education, on main effects. Results: Marked reductions in the odds of achievement were observed, emerging at the earliest levels of schooling for both single-affected [adjusted odds ratio (aOR), 0.50; 95% CI 0.49-0.51] and dual-affected (aOR 0.29, 95% CI 0.28-0.30) pairs and persisting thereafter [aOR range (single), 0.52-0.65; aOR range (dual), 0.30-0.40]. This pattern was repeated for analyses within diagnosis/diagnostic group. Main results were robust to adjustment for offspring mental health and parent education level. Conclusions: Parental mental illness is associated with profound reductions in educational attainment in the subsequent generation, with children from dual-affected families at uniquely high risk.

Background: Both maternal and, separately, paternal mental illness are associated with diminished academic attainment among children. However, the differential impacts of diagnostic type and degree of parental burden (e.g. one v. both parents affected) on these functional outcomes are unknown. Methods: Using the Swedish national patient (NPR) and multi-generation (MGR) registers, 2 226 451 children (1 290 157 parental pairs), born 1 January 1973-31 December 1997, were followed through 31 December 2013. Diagnostic status of all cohort members was defined for eleven psychiatric disorders, and families classed by exposure: (1) parents affected with any disorder, (2) parents affected with a disorder group (e.g. neuropsychiatric disorders), and (3) parents affected with a specific disorder (e.g. ADHD). Pairs were further defined as 'unaffected,' 'single-affected,', or 'dual-affected.' Among offspring, the study evaluated fulfillment of four academic milestones, from compulsory (primary) school through University (college). Sensitivity analyses considered the impact of child's own mental health, as well as parental education, on main effects. Results: Marked reductions in the odds of achievement were observed, emerging at the earliest levels of schooling for both single-affected [adjusted odds ratio (aOR), 0.50; 95% CI 0.49-0.51] and dual-affected (aOR 0.29, 95% CI 0.28-0.30) pairs and persisting thereafter [aOR range (single), 0.52-0.65; aOR range (dual), 0.30-0.40]. This pattern was repeated for analyses within diagnosis/diagnostic group. Main results were robust to adjustment for offspring mental health and parent education level. Conclusions: Parental mental illness is associated with profound reductions in educational attainment in the subsequent generation, with children from dual-affected families at uniquely high risk.

Background: Both maternal and, separately, paternal mental illness are associated with diminished academic attainment among children. However, the differential impacts of diagnostic type and degree of parental burden (e.g. one v. both parents affected) on these functional outcomes are unknown. Methods: Using the Swedish national patient (NPR) and multi-generation (MGR) registers, 2 226 451 children (1 290 157 parental pairs), born 1 January 1973-31 December 1997, were followed through 31 December 2013. Diagnostic status of all cohort members was defined for eleven psychiatric disorders, and families classed by exposure: (1) parents affected with any disorder, (2) parents affected with a disorder group (e.g. neuropsychiatric disorders), and (3) parents affected with a specific disorder (e.g. ADHD). Pairs were further defined as 'unaffected,' 'single-affected,', or 'dual-affected.' Among offspring, the study evaluated fulfillment of four academic milestones, from compulsory (primary) school through University (college). Sensitivity analyses considered the impact of child's own mental health, as well as parental education, on main effects. Results: Marked reductions in the odds of achievement were observed, emerging at the earliest levels of schooling for both single-affected [adjusted odds ratio (aOR), 0.50; 95% CI 0.49-0.51] and dual-affected (aOR 0.29, 95% CI 0.28-0.30) pairs and persisting thereafter [aOR range (single), 0.52-0.65; aOR range (dual), 0.30-0.40]. This pattern was repeated for analyses within diagnosis/diagnostic group. Main results were robust to adjustment for offspring mental health and parent education level. Conclusions: Parental mental illness is associated with profound reductions in educational attainment in the subsequent generation, with children from dual-affected families at uniquely high risk.

Background: Both maternal and, separately, paternal mental illness are associated with diminished academic attainment among children. However, the differential impacts of diagnostic type and degree of parental burden (e.g. one v. both parents affected) on these functional outcomes are unknown. Methods: Using the Swedish national patient (NPR) and multi-generation (MGR) registers, 2 226 451 children (1 290 157 parental pairs), born 1 January 1973-31 December 1997, were followed through 31 December 2013. Diagnostic status of all cohort members was defined for eleven psychiatric disorders, and families classed by exposure: (1) parents affected with any disorder, (2) parents affected with a disorder group (e.g. neuropsychiatric disorders), and (3) parents affected with a specific disorder (e.g. ADHD). Pairs were further defined as 'unaffected,' 'single-affected,', or 'dual-affected.' Among offspring, the study evaluated fulfillment of four academic milestones, from compulsory (primary) school through University (college). Sensitivity analyses considered the impact of child's own mental health, as well as parental education, on main effects. Results: Marked reductions in the odds of achievement were observed, emerging at the earliest levels of schooling for both single-affected [adjusted odds ratio (aOR), 0.50; 95% CI 0.49-0.51] and dual-affected (aOR 0.29, 95% CI 0.28-0.30) pairs and persisting thereafter [aOR range (single), 0.52-0.65; aOR range (dual), 0.30-0.40]. This pattern was repeated for analyses within diagnosis/diagnostic group. Main results were robust to adjustment for offspring mental health and parent education level. Conclusions: Parental mental illness is associated with profound reductions in educational attainment in the subsequent generation, with children from dual-affected families at uniquely high risk.

Existing methods for generating synthetic genotype data are ill-suited for replicating the effects of assortative mating (AM). We propose rb_dplr, a novel and computationally efficient algorithm for generating high-dimensional binary random variates that effectively recapitulates AM-induced genetic architectures using the Bahadur order-2 approximation of the multivariate Bernoulli distribution. The rBahadur R library is available through the Comprehensive R Archive Network at https://CRAN.R-project.org/package=rBahadur .

In bipolar disorder, dysregulation of affect is a core feature while knowledge on affective lability in schizophrenia is sparse. Research on affective lability in partners to individuals with schizophrenia or bipolar disorder is also lacking. The objective of this study was to investigate affective lability in parents with schizophrenia or bipolar disorder, and their co-parents without these disorders. The Danish High Risk and Resilience Study – VIA 7 is a population-based cohort study. This study focuses on parents diagnosed with schizophrenia (n = 148), their co-parents (n = 157), parents with bipolar disorder (n = 98), their co-parents (n = 89) and control parents (n = 359). The Affective Lability Scale – short form (ALS-SF) was used to measure affective lability. We found significantly higher levels of affective lability in parents with schizophrenia and bipolar disorder compared with controls, but no significant differences between bipolar disorder and schizophrenia. Co-parents to parents with schizophrenia had significantly higher levels of affective lability compared to controls. Our results add to the existing knowledge concerning underlying transdiagnostic factors and nonrandom mating in schizophrenia and bipolar disorder and highlight the need for studies of parental affective lability as a potential risk factor for offspring in families with parental schizophrenia or bipolar disorder.

In bipolar disorder, dysregulation of affect is a core feature while knowledge on affective lability in schizophrenia is sparse. Research on affective lability in partners to individuals with schizophrenia or bipolar disorder is also lacking. The objective of this study was to investigate affective lability in parents with schizophrenia or bipolar disorder, and their co-parents without these disorders. The Danish High Risk and Resilience Study – VIA 7 is a population-based cohort study. This study focuses on parents diagnosed with schizophrenia (n = 148), their co-parents (n = 157), parents with bipolar disorder (n = 98), their co-parents (n = 89) and control parents (n = 359). The Affective Lability Scale – short form (ALS-SF) was used to measure affective lability. We found significantly higher levels of affective lability in parents with schizophrenia and bipolar disorder compared with controls, but no significant differences between bipolar disorder and schizophrenia. Co-parents to parents with schizophrenia had significantly higher levels of affective lability compared to controls. Our results add to the existing knowledge concerning underlying transdiagnostic factors and nonrandom mating in schizophrenia and bipolar disorder and highlight the need for studies of parental affective lability as a potential risk factor for offspring in families with parental schizophrenia or bipolar disorder.

BACKGROUND: Both maternal and, separately, paternal mental illness are associated with diminished academic attainment among children. However, the differential impacts of diagnostic type and degree of parental burden (e.g. one v. both parents affected) on these functional outcomes are unknown. METHODS: Using the Swedish national patient (NPR) and multi-generation (MGR) registers, 2 226 451 children (1 290 157 parental pairs), born 1 January 1973-31 December 1997, were followed through 31 December 2013. Diagnostic status of all cohort members was defined for eleven psychiatric disorders, and families classed by exposure: (1) parents affected with any disorder, (2) parents affected with a disorder group (e.g. neuropsychiatric disorders), and (3) parents affected with a specific disorder (e.g. ADHD). Pairs were further defined as 'unaffected,' 'single-affected,', or 'dual-affected.' Among offspring, the study evaluated fulfillment of four academic milestones, from compulsory (primary) school through University (college). Sensitivity analyses considered the impact of child's own mental health, as well as parental education, on main effects. RESULTS: Marked reductions in the odds of achievement were observed, emerging at the earliest levels of schooling for both single-affected [adjusted odds ratio (aOR), 0.50; 95% CI 0.49-0.51] and dual-affected (aOR 0.29, 95% CI 0.28-0.30) pairs and persisting thereafter [aOR range (single), 0.52-0.65; aOR range (dual), 0.30-0.40]. This pattern was repeated for analyses within diagnosis/diagnostic group. Main results were robust to adjustment for offspring mental health and parent education level. CONCLUSIONS: Parental mental illness is associated with profound reductions in educational attainment in the subsequent generation, with children from dual-affected families at uniquely high risk.

Background: Both maternal and, separately, paternal mental illness are associated with diminished academic attainment among children. However, the differential impacts of diagnostic type and degree of parental burden (e.g. one v. both parents affected) on these functional outcomes are unknown. Methods: Using the Swedish national patient (NPR) and multi-generation (MGR) registers, 2 226 451 children (1 290 157 parental pairs), born 1 January 1973-31 December 1997, were followed through 31 December 2013. Diagnostic status of all cohort members was defined for eleven psychiatric disorders, and families classed by exposure: (1) parents affected with any disorder, (2) parents affected with a disorder group (e.g. neuropsychiatric disorders), and (3) parents affected with a specific disorder (e.g. ADHD). Pairs were further defined as 'unaffected,' 'single-affected,', or 'dual-affected.' Among offspring, the study evaluated fulfillment of four academic milestones, from compulsory (primary) school through University (college). Sensitivity analyses considered the impact of child's own mental health, as well as parental education, on main effects. Results: Marked reductions in the odds of achievement were observed, emerging at the earliest levels of schooling for both single-affected [adjusted odds ratio (aOR), 0.50; 95% CI 0.49-0.51] and dual-affected (aOR 0.29, 95% CI 0.28-0.30) pairs and persisting thereafter [aOR range (single), 0.52-0.65; aOR range (dual), 0.30-0.40]. This pattern was repeated for analyses within diagnosis/diagnostic group. Main results were robust to adjustment for offspring mental health and parent education level. Conclusions: Parental mental illness is associated with profound reductions in educational attainment in the subsequent generation, with children from dual-affected families at uniquely high risk.

European whitefish (Coregonus lavaretus) forms reproductively isolated sub-populations with different body sizes in the lakes where northern pike (Esox lucius) exists. It has been hypothesized that the initial reproductive isolation between ecotypes arises through size-assortative mate choice or because small and large individuals arrive to the spawning grounds at different times. To test these hypotheses, I caught and measured both breeding whitefish pairs and singular whitefish on the spawning grounds over the spawning season. There was no correlation between the lengths of males and females in breeding pairs, indicating that mate selection was random with respect to body size. There were no significant differences in body length between sampling dates during the field period in November 2021, suggesting that there is no divergence in spawning time between large and small individuals. Thus, neither of the two hypotheses were supported. Interestingly, males have significantly higher amount of breeding tubercles than females according to my results, which could be a selective factor in mate selection. However, the function of the tubercles is yet poorly understood.

Identifying mechanisms limiting hybridization is a central goal of speciation research. Here, we studied premating and postmating barriers to hybridization between two ant species, Formica selysi and Formica cinerea. These species hybridize in the Rhône valley in Switzerland, where they form a mosaic hybrid zone, with limited introgression from F. selysi into F. cinerea. There was no sign of temporal isolation between the two species in the production of queens and males. With choice experiments, we showed that queens and males strongly prefer to mate with conspecifics. Yet, we did not detect postmating barriers caused by genetic incompatibilities. Specifically, hybrids of all sexes and castes were found in the field and F1 hybrid workers did not show reduced viability compared to nonhybrid workers. To gain insights into the cues involved in species recognition, we analyzed the cuticular hydrocarbons (CHCs) of queens, males, and workers and staged dyadic encounters between workers. CHC profiles differed markedly between species, but were similar in F. cinerea and hybrids. Accordingly, workers also discriminated species, but they did not discriminate F. cinerea and hybrids. We discuss how the CHC-based recognition system of ants may facilitate the establishment of premating barriers to hybridization, independent of hybridization costs.

We study the contribution of parental educational assortative mating to the intergenerational transmission of educational attainment. We develop an empirical model for educational correlations within the family in which parental educational sorting can translate into intergenerational transmission jointly by both parents, or transmission can originate from each parent independently. Estimating the model using educational attainment from Danish population-based administrative data for over 400,000 families, we find that on aver- age 75 percent of the intergenerational correlation in education is driven by the joint contribution of the par- ents. We also document a 38 percent decline of assortative mating in education for parents born between the early 1920s and the early 1950s. While the raw correlations also show decreases in father- and mother- specific intergenerational transmissions of educational attainment, our model shows that once we decompose all factors of intergenerational mobility, the share of intergenerational transmission accounted for by parent-specific factors increased from 7 to 27 percent; an increase compensated by a corresponding fall in joint intergenerational transmission from both parents, leaving total intergenerational persistence un- changed. The mechanisms of intergenerational transmission have changed, with an increased importance of one-to-one parent-child relationships.

Understanding evolutionary phenomena that involve size assortative mating requires elucidating the generating mechanisms on which assortment is based. Although various mechanisms have been suggested, their relative importance may differ across taxonomic groups. Males selecting for large, fecund females combined with the dominance of large males in the competition for females has been suggested as a major mechanism in specific groups. However, raptors do not appear to conform to this, because the selection for smallness among males (assumed in a theory of reversed sexual size dimorphism) and the selection for largeness among males (assumed in the theory of size assortative mating) are in opposite directions. We studied the assortative mating during a long-term study of the Ryukyu Scops Owls Otus elegans interpositus. Significant assortative mating was found for culmen length (from the base to the tip of the bill) and wing length (from the bend of the wing to the tip of the longest primary). Statistical control of the spatial and temporal accessibility of potential mates did not affect the assortment. Males with short wings had slightly higher fitness components than those with long wings, and females settling early tended to have small wings. Considering that early-settling females can preferentially choose their mates, these results suggest that smaller females have an advantage when choosing smaller males with good reproductive performance. Improved flying and hunting ability of smaller individuals may be the background of choosing smaller individuals. We propose that, not passive process like similarity between individuals and their potential mates, but active mate choice for small individuals is an explanation for the assortative mating in this owl.

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.

Understanding evolutionary phenomena that involve size assortative mating requires elucidating the generating mechanisms on which assortment is based. Although various mechanisms have been suggested, their relative importance may differ across taxonomic groups. Males selecting for large, fecund females combined with the dominance of large males in the competition for females has been suggested as a major mechanism in specific groups. However, raptors do not appear to conform to this, because the selection for smallness among males (assumed in a theory of reversed sexual size dimorphism) and the selection for largeness among males (assumed in the theory of size assortative mating) are in opposite directions. We studied the assortative mating during a long-term study of the Ryukyu Scops Owls Otus elegans interpositus. Significant assortative mating was found for culmen length (from the base to the tip of the bill) and wing length (from the bend of the wing to the tip of the longest primary). Statistical control of the spatial and temporal accessibility of potential mates did not affect the assortment. Males with short wings had slightly higher fitness components than those with long wings, and females settling early tended to have small wings. Considering that early-settling females can preferentially choose their mates, these results suggest that smaller females have an advantage when choosing smaller males with good reproductive performance. Improved flying and hunting ability of smaller individuals may be the background of choosing smaller individuals. We propose that, not passive process like similarity between individuals and their potential mates, but active mate choice for small individuals is an explanation for the assortative mating in this owl.

Background: Psychiatric disorders are highly polygenic and show patterns of partner resemblance. Partner resemblance has direct population-level genetic implications if it is caused by assortative mating, but not if it is caused by convergence or social homogamy. Using genetics may help distinguish these different mechanisms. Here, we investigated whether partner resemblance for schizophrenia and bipolar disorder is influenced by assortative mating using polygenic risk scores (PRS). Methods: Polygenic risk scores from The Danish High-Risk and Resilience Study-VIA 7 were compared between parents in three subsamples: population-based control parent pairs (N=198), parent pairs where at least one parent had schizophrenia (N=193), and parent pairs where at least one parent had bipolar disorder (N=115). Results: The PRS for schizophrenia was predictive of schizophrenia in the full sample and showed significant correlation between parent pairs (r = 0.121, p = 0.0440), indicative of assortative mating. The PRS for bipolar disorder was also correlated between parent pairs (r = 0.162, p = 0.0067), but was not predictive of bipolar disorder in the full sample, limiting the interpretation. Conclusions: Our study provides genetic evidence for assortative mating for schizophrenia, with important implications for our understanding of the genetics of schizophrenia.

We quantify intergenerational and assortative processes by comparing different degrees of kinship within the same generation. This “horizontal” approach yields more, and more distant kinship moments than traditional methods, which allows us to account for the transmission of latent advantages in a detailed intergenerational model. Using Swedish registers, we find strong persistence in the latent determinants of status, and a striking degree of sorting—to explain the similarity of distant kins, assortative matching must be much stronger than previously thought. Latent genetic influences explain little of the variance in educational attainment, and sorting occurs primarily in non-genetic factors.

Background: Psychiatric disorders are highly polygenic and show patterns of partner resemblance. Partner resemblance has direct population-level genetic implications if it is caused by assortative mating, but not if it is caused by convergence or social homogamy. Using genetics may help distinguish these different mechanisms. Here, we investigated whether partner resemblance for schizophrenia and bipolar disorder is influenced by assortative mating using polygenic risk scores (PRS). Methods: Polygenic risk scores from The Danish High-Risk and Resilience Study-VIA 7 were compared between parents in three subsamples: population-based control parent pairs (N=198), parent pairs where at least one parent had schizophrenia (N=193), and parent pairs where at least one parent had bipolar disorder (N=115). Results: The PRS for schizophrenia was predictive of schizophrenia in the full sample and showed significant correlation between parent pairs (r = 0.121, p = 0.0440), indicative of assortative mating. The PRS for bipolar disorder was also correlated between parent pairs (r = 0.162, p = 0.0067), but was not predictive of bipolar disorder in the full sample, limiting the interpretation. Conclusions: Our study provides genetic evidence for assortative mating for schizophrenia, with important implications for our understanding of the genetics of schizophrenia.

When did marriage become strongly assortative? Is it a recent development, aconsequence of increased female employment and a cause of rising inequality? A longrun perspective is necessary to answer this question. This paper uses a uniquely suitabledatabase from Quebec 1800{1970 to provide such a perspective. First, it develops anovel method which reveals that marriage was highly assortative as far back as the earlynineteenth century. Next, it shows this matching depended on the individual humancapital of women, not just on family backgrounds. Finally, it shows that mothers hada causal impact on child outcomes independently from fathers. Thus, despite deeplyconservative gender norms, marriage matching, info:eu-repo/semantics/published

We study the contribution of parental educational assortative mating to the intergenerational transmission of educational attainment. We develop an empirical model for educational correlations within the family in which parental educational sorting can translate into intergenerational transmission jointly by both parents, or transmission can originate from each parent independently. Estimating the model using educational attainment from Danish population-based administrative data for over 400,000 families, we find that on average 75 percent of the intergenerational correlation in education is driven by the joint contribution of the parents. We also document a 38 percent decline of assortative mating in education for parents born between the early 1920s and the early 1950s. While the raw correlations also show decreases in father- and mother-specific intergenerational transmissions of educational attainment, our model shows that once we decompose all factors of intergenerational mobility, the share of intergenerational transmission accounted for by parent-specific factors increased from 7 to 27 percent; an increase compensated by a corresponding fall in joint intergenerational transmission from both parents, leaving total intergenerational persistence unchanged. The mechanisms of intergenerational transmission have changed, with an increased importance of one-to-one parent-child relationships.

European whitefish (Coregonus lavaretus) forms reproductively isolated sub-populations with different body sizes in the lakes where northern pike (Esox lucius) exists. It has been hypothesized that the initial reproductive isolation between ecotypes arises through size-assortative mate choice or because small and large individuals arrive to the spawning grounds at different times. To test these hypotheses, I caught and measured both breeding whitefish pairs and singular whitefish on the spawning grounds over the spawning season. There was no correlation between the lengths of males and females in breeding pairs, indicating that mate selection was random with respect to body size. There were no significant differences in body length between sampling dates during the field period in November 2021, suggesting that there is no divergence in spawning time between large and small individuals. Thus, neither of the two hypotheses were supported. Interestingly, males have significantly higher amount of breeding tubercles than females according to my results, which could be a selective factor in mate selection. However, the function of the tubercles is yet poorly understood.

The last two centuries have seen dramatic shifts in labor and demography: a precipitous drop in fertility rates, a dramatic increase in human capital, and the economic empowerment of women. Economic theorists often hypothesize that these transformations played a vital role in the transition to modern economic growth. This dissertation uses historical vital records from the Canadian province of Quebec and applied microeconomic methods to test the assumptions that underpin these theories. First, it shows that parents did not target a family size before the demographic transition. Second, it shows that family size only had a modest impact on the accumulation of human capital. Third, it shows that assortative marriage, unlike family size, mattered long before many might expect. Quebec, with its unusual demographic regime and exceptionally high quality demographic data, provides solid empirical evidence to support these claims. The IMPQ (l’Infrastructure intégrée des microdonnées historiques de la population québécoise) is a large new database of family reconstitutions from baptism, burial, and marriage records (IMPQ 2020). It integrates two previous databases, the BALSAC database and the RPQA (Project Balsac 2020, PRDH 2020). While the dataset is still being extended, as of writing it contains 1.8 million unique births, 0.8 million unique deaths, and 4.2 million unique marriages from 1481–1992 (though births and deaths are limited to a particular region after 1849, there are very few records from before 1620, and the births and marriages are only available through 1971). Moreover, in those records a total of 2.8 million other individuals are mentioned besides the main participants, which provides additional observations over time for many people besides their own vital events. The first chapter of my dissertation, co-authored with Gregory Clark and Neil Cummins and published in Demography, considers the demographic transition. Was this decline in fertility due to changi

Genome duplication in plants is thought to be a route to speciation due to cytotype incompatibility. However, to reduce cross-pollination between cytotypes in animal-pollinated species, distinctive floral phenotypes, which would allow pollinator-mediated assortative mating between flowers, are also expected. Chamerion angustifolium is a Holarctic species that forms a hybrid zone between diploid and tetraploid populations in the North American Rocky Mountains. Extensive research has shown that these cytotypes differ in many ways, including some floral traits, and that pollinators can discriminate between cytotypes, leading to assortative mating. However, two signals commonly used by insect pollinators have not been measured for this species, namely petal colour and floral scent. Using greenhouse-grown diploids and tetraploids of C. angustifolium from the ploidy hybrid-zone in the North American Rocky Mountains, we show that both floral scent signals and petal reflectance differ between cytotypes. These differences, along with differences in flower size shown previously, could help explain pollinator-mediated assortative mating observed in previous studies. However, these differences in floral phenotypes may vary in importance to pollinators. While the differences in scent included common floral volatiles readily detected by bumblebees, the differences in petal reflectance may not be perceived by bees based on their visual sensitivity across the spectra. Thus, our results suggest that differences in floral volatile emissions are more likely to contribute to pollinator discrimination between cytotypes and highlight the importance of understanding the sensory systems of pollinators when examining floral signals.

Genome duplication in plants is thought to be a route to speciation due to cytotype incompatibility. However, to reduce cross-pollination between cytotypes in animal-pollinated species, distinctive floral phenotypes, which would allow pollinator-mediated assortative mating between flowers, are also expected. Chamerion angustifolium is a Holarctic species that forms a hybrid zone between diploid and tetraploid populations in the North American Rocky Mountains. Extensive research has shown that these cytotypes differ in many ways, including some floral traits, and that pollinators can discriminate between cytotypes, leading to assortative mating. However, two signals commonly used by insect pollinators have not been measured for this species, namely petal colour and floral scent. Using greenhouse-grown diploids and tetraploids of C. angustifolium from the ploidy hybrid-zone in the North American Rocky Mountains, we show that both floral scent signals and petal reflectance differ between cytotypes. These differences, along with differences in flower size shown previously, could help explain pollinator-mediated assortative mating observed in previous studies. However, these differences in floral phenotypes may vary in importance to pollinators. While the differences in scent included common floral volatiles readily detected by bumblebees, the differences in petal reflectance may not be perceived by bees based on their visual sensitivity across the spectra. Thus, our results suggest that differences in floral volatile emissions are more likely to contribute to pollinator discrimination between cytotypes and highlight the importance of understanding the sensory systems of pollinators when examining floral signals.

Genome duplication in plants is thought to be a route to speciation due to cytotype incompatibility. However, to reduce cross-pollination between cytotypes in animal-pollinated species, distinctive floral phenotypes, which would allow pollinator-mediated assortative mating between flowers, are also expected. Chamerion angustifolium is a Holarctic species that forms a hybrid zone between diploid and tetraploid populations in the North American Rocky Mountains. Extensive research has shown that these cytotypes differ in many ways, including some floral traits, and that pollinators can discriminate between cytotypes, leading to assortative mating. However, two signals commonly used by insect pollinators have not been measured for this species, namely petal colour and floral scent. Using greenhouse-grown diploids and tetraploids of C. angustifolium from the ploidy hybrid-zone in the North American Rocky Mountains, we show that both floral scent signals and petal reflectance differ between cytotypes. These differences, along with differences in flower size shown previously, could help explain pollinator-mediated assortative mating observed in previous studies. However, these differences in floral phenotypes may vary in importance to pollinators. While the differences in scent included common floral volatiles readily detected by bumblebees, the differences in petal reflectance may not be perceived by bees based on their visual sensitivity across the spectra. Thus, our results suggest that differences in floral volatile emissions are more likely to contribute to pollinator discrimination between cytotypes and highlight the importance of understanding the sensory systems of pollinators when examining floral signals.

The last two centuries have seen dramatic shifts in labor and demography: a precipitous drop in fertility rates, a dramatic increase in human capital, and the economic empowerment of women. Economic theorists often hypothesize that these transformations played a vital role in the transition to modern economic growth. This dissertation uses historical vital records from the Canadian province of Quebec and applied microeconomic methods to test the assumptions that underpin these theories. First, it shows that parents did not target a family size before the demographic transition. Second, it shows that family size only had a modest impact on the accumulation of human capital. Third, it shows that assortative marriage, unlike family size, mattered long before many might expect. Quebec, with its unusual demographic regime and exceptionally high quality demographic data, provides solid empirical evidence to support these claims. The IMPQ (l’Infrastructure intégrée des microdonnées historiques de la population québécoise) is a large new database of family reconstitutions from baptism, burial, and marriage records (IMPQ 2020). It integrates two previous databases, the BALSAC database and the RPQA (Project Balsac 2020, PRDH 2020). While the dataset is still being extended, as of writing it contains 1.8 million unique births, 0.8 million unique deaths, and 4.2 million unique marriages from 1481–1992 (though births and deaths are limited to a particular region after 1849, there are very few records from before 1620, and the births and marriages are only available through 1971). Moreover, in those records a total of 2.8 million other individuals are mentioned besides the main participants, which provides additional observations over time for many people besides their own vital events. The first chapter of my dissertation, co-authored with Gregory Clark and Neil Cummins and published in Demography, considers the demographic transition. Was this decline in fertility due to changi

Genome duplication in plants is thought to be a route to speciation due to cytotype incompatibility. However, to reduce cross-pollination between cytotypes in animal-pollinated species, distinctive floral phenotypes, which would allow pollinator-mediated assortative mating between flowers, are also expected. Chamerion angustifolium is a Holarctic species that forms a hybrid zone between diploid and tetraploid populations in the North American Rocky Mountains. Extensive research has shown that these cytotypes differ in many ways, including some floral traits, and that pollinators can discriminate between cytotypes, leading to assortative mating. However, two signals commonly used by insect pollinators have not been measured for this species, namely petal colour and floral scent. Using greenhouse-grown diploids and tetraploids of C. angustifolium from the ploidy hybrid-zone in the North American Rocky Mountains, we show that both floral scent signals and petal reflectance differ between cytotypes. These differences, along with differences in flower size shown previously, could help explain pollinator-mediated assortative mating observed in previous studies. However, these differences in floral phenotypes may vary in importance to pollinators. While the differences in scent included common floral volatiles readily detected by bumblebees, the differences in petal reflectance may not be perceived by bees based on their visual sensitivity across the spectra. Thus, our results suggest that differences in floral volatile emissions are more likely to contribute to pollinator discrimination between cytotypes and highlight the importance of understanding the sensory systems of pollinators when examining floral signals.

Marriage patterns are a key element in the social reproduction of inequalities because, through marriage, socio-economic resources are distributed among individuals and households. Furthermore, the measure by which individuals from different groups marry each other can be considered as an indicator of the grade of openness of a society. From a historical perspective, modernization theory has traditionally predicted a decrease in marital homogamy by social origin. Long-term trends in social homogamy have been investigated in the social history field, and empirical evidence is quite diverse across contexts and periods. We analyzed patterns of social homogamy in Milan using new couple-level data on marriages between the end of the 19th and the first half of the 20th century. Following the modernization framework, we hypothesized that the transition towards an industrial society should be accompanied by an increase in social heterogamy. Results show that, net of changing marginal distributions across social classes, patterns of couple formation remain substantively the same across time. Men appear less mobile than women, who have a higher tendency towards upward marital mobility. As for intermarriage among social classes, boundaries between the top and bottom classes, and barriers between manual and non-manual workers remained strong across time. These results, as previously found in other contexts, do not fully corroborate the modernization theory.

Genome duplication in plants is thought to be a route to speciation due to cytotype incompatibility. However, to reduce cross-pollination between cytotypes in animal-pollinated species, distinctive floral phenotypes, which would allow pollinator-mediated assortative mating between flowers, are also expected. Chamerion angustifolium is a Holarctic species that forms a hybrid zone between diploid and tetraploid populations in the North American Rocky Mountains. Extensive research has shown that these cytotypes differ in many ways, including some floral traits, and that pollinators can discriminate between cytotypes, leading to assortative mating. However, two signals commonly used by insect pollinators have not been measured for this species, namely petal colour and floral scent. Using greenhouse-grown diploids and tetraploids of C. angustifolium from the ploidy hybrid-zone in the North American Rocky Mountains, we show that both floral scent signals and petal reflectance differ between cytotypes. These differences, along with differences in flower size shown previously, could help explain pollinator-mediated assortative mating observed in previous studies. However, these differences in floral phenotypes may vary in importance to pollinators. While the differences in scent included common floral volatiles readily detected by bumblebees, the differences in petal reflectance may not be perceived by bees based on their visual sensitivity across the spectra. Thus, our results suggest that differences in floral volatile emissions are more likely to contribute to pollinator discrimination between cytotypes and highlight the importance of understanding the sensory systems of pollinators when examining floral signals.

This paper examines the consequences of political, economic and social change in mid-twentieth century China for patterns of assortative mating by both education and class. Traditionally in China, marriages were arranged by parents, and ideally matched families of similar socioeconomic status. However, the Marriage Law passed by the People's Republic of China in 1950 promoted free choice and forbade arranged marriage and other interference by families in the marriage decisions of their children. Later, Land Reform, Collectivization and other movements had profound impacts on rural household organization and social relations. We investigate their effects on assortative mating by using novel linked administrative data compiled in rural Shanxi Province in North China in the mid-1960s. These data record the education and family class labels (jiating chushen) of spouses for 1459 couples in 30 villages. The class labels were assigned in the 1950s based on family landholding before the Land Reform and became hereditary. We find that class label had effects above and beyond those of education, suggesting that assortative mating studies that only consider education overlook an important dimension of social status in marriage patterns, and thereby overstate the overall permeability of boundaries between social groups. Furthermore, by comparing couples according to whether they married before or after 1949, we find that patterns of homogamy and hypergamy remained highly stable in the face of substantial social transformation after 1949.

This paper examines the consequences of political, economic and social change in mid-twentieth century China for patterns of assortative mating by both education and class. Traditionally in China, marriages were arranged by parents, and ideally matched families of similar socioeconomic status. However, the Marriage Law passed by the People's Republic of China in 1950 promoted free choice and forbade arranged marriage and other interference by families in the marriage decisions of their children. Later, Land Reform, Collectivization and other movements had profound impacts on rural household organization and social relations. We investigate their effects on assortative mating by using novel linked administrative data compiled in rural Shanxi Province in North China in the mid-1960s. These data record the education and family class labels (jiating chushen) of spouses for 1459 couples in 30 villages. The class labels were assigned in the 1950s based on family landholding before the Land Reform and became hereditary. We find that class label had effects above and beyond those of education, suggesting that assortative mating studies that only consider education overlook an important dimension of social status in marriage patterns, and thereby overstate the overall permeability of boundaries between social groups. Furthermore, by comparing couples according to whether they married before or after 1949, we find that patterns of homogamy and hypergamy remained highly stable in the face of substantial social transformation after 1949.

Seasonal migration is a complex and variable behaviour with the potential to promote reproductive isolation. In Eurasian blackcaps (Sylvia atricapilla), a migratory divide in central Europe separating populations with southwest (SW) and southeast (SE) autumn routes may facilitate isolation, and individuals using new wintering areas in Britain show divergence from Mediterranean winterers. We tracked 100 blackcaps in the wild to characterize these strategies. Blackcaps to the west and east of the divide used predominantly SW and SE directions, respectively, but close to the contact zone many individuals took intermediate (S) routes. At 14.0° E, we documented a sharp transition from SW to SE migratory directions across only 27 (10-86) km, implying a strong selection gradient across the divide. Blackcaps wintering in Britain took northwesterly migration routes from continental European breeding grounds. They originated from a surprisingly extensive area, spanning 2000 km of the breeding range. British winterers bred in sympatry with SW-bound migrants but arrived 9.8 days earlier on the breeding grounds, suggesting some potential for assortative mating by timing. Overall, our data reveal complex variation in songbird migration and suggest that selection can maintain variation in migration direction across short distances while enabling the spread of a novel strategy across a wide range.

Educational assortative mating and earnings inequality has both increased in both Europe and the United States in the last decades. As a result, educational assortative mating, or educational homogamy, has been suggested as a potential explanation for the increase in earnings inequality. According to this hypothesis increased sorting on education will lead to polarization between lower and higher-educated couples where the advantages of the latter will compound on one another and lead to increased economic inequality. The majority of the studies to date report a non-relationship between educational assortative mating and earnings inequality, one of the exceptions being a study of Denmark. This exception has led sociologists to theorize that the impact of educational assortative mating could be especially strong in the Nordic countries. In this study I test this hypothesis by employing a novel decomposition method, the Theil-index, to answer if increases in educational assortative mating are associated with increases in earnings inequality in Sweden between 2000 and 2010, using data from the Standard of Living Survey (LNU). The result is a non-relationship between homogamy and earnings inequality and an overall decrease in earnings inequality in the sample. The result is another null result for the hypothesis that educational homogamy leads to inequality, and points to a larger discrepancy between singles and couples than between couples. If corroborated, this decrease in earnings inequality would mean a divergence, in earnings inequality, between partnered individuals and the general population. Future studies should focus on the extent of this divergence.

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.

Seasonal migration is a complex and variable behaviour with the potential to promote reproductive isolation. In Eurasian blackcaps (Sylvia atricapilla), a migratory divide in central Europe separating populations with southwest (SW) and southeast (SE) autumn routes may facilitate isolation, and individuals using new wintering areas in Britain show divergence from Mediterranean winterers. We tracked 100 blackcaps in the wild to characterize these strategies. Blackcaps to the west and east of the divide used predominantly SW and SE directions, respectively, but close to the contact zone many individuals took intermediate (S) routes. At 14.0° E, we documented a sharp transition from SW to SE migratory directions across only 27 (10-86) km, implying a strong selection gradient across the divide. Blackcaps wintering in Britain took northwesterly migration routes from continental European breeding grounds. They originated from a surprisingly extensive area, spanning 2000 km of the breeding range. British winterers bred in sympatry with SW-bound migrants but arrived 9.8 days earlier on the breeding grounds, suggesting some potential for assortative mating by timing. Overall, our data reveal complex variation in songbird migration and suggest that selection can maintain variation in migration direction across short distances while enabling the spread of a novel strategy across a wide range.

This paper examines the consequences of political, economic and social change in mid-twentieth century China for patterns of assortative mating by both education and class. Traditionally in China, marriages were arranged by parents, and ideally matched families of similar socioeconomic status. However, the Marriage Law passed by the People's Republic of China in 1950 promoted free choice and forbade arranged marriage and other interference by families in the marriage decisions of their children. Later, Land Reform, Collectivization and other movements had profound impacts on rural household organization and social relations. We investigate their effects on assortative mating by using novel linked administrative data compiled in rural Shanxi Province in North China in the mid-1960s. These data record the education and family class labels (jiating chushen) of spouses for 1459 couples in 30 villages. The class labels were assigned in the 1950s based on family landholding before the Land Reform and became hereditary. We find that class label had effects above and beyond those of education, suggesting that assortative mating studies that only consider education overlook an important dimension of social status in marriage patterns, and thereby overstate the overall permeability of boundaries between social groups. Furthermore, by comparing couples according to whether they married before or after 1949, we find that patterns of homogamy and hypergamy remained highly stable in the face of substantial social transformation after 1949.

Seasonal migration is a complex and variable behaviour with the potential to promote reproductive isolation. In Eurasian blackcaps (Sylvia atricapilla), a migratory divide in central Europe separating populations with southwest (SW) and southeast (SE) autumn routes may facilitate isolation, and individuals using new wintering areas in Britain show divergence from Mediterranean winterers. We tracked 100 blackcaps in the wild to characterize these strategies. Blackcaps to the west and east of the divide used predominantly SW and SE directions, respectively, but close to the contact zone many individuals took intermediate (S) routes. At 14.0° E, we documented a sharp transition from SW to SE migratory directions across only 27 (10-86) km, implying a strong selection gradient across the divide. Blackcaps wintering in Britain took northwesterly migration routes from continental European breeding grounds. They originated from a surprisingly extensive area, spanning 2000 km of the breeding range. British winterers bred in sympatry with SW-bound migrants but arrived 9.8 days earlier on the breeding grounds, suggesting some potential for assortative mating by timing. Overall, our data reveal complex variation in songbird migration and suggest that selection can maintain variation in migration direction across short distances while enabling the spread of a novel strategy across a wide range.

This article describes trends in parental wealth homogamy among union cohorts formed between 1987 and 2013 in Denmark. Using high-quality register data on the wealth of parents during the year of partnering, we show that the correlation between partners’ levels of parental wealth is considerably lower compared with estimates from research on other countries. Nonetheless, parental wealth homogamy is high at the very top of the parental wealth distribution, and individuals from wealthy families are relatively unlikely to partner with individuals from families with low wealth. Parental wealth correlations among partners are higher when only parental assets rather than net wealth are examined, implying that the former might be a better measure for studying many social stratification processes. Most specifications indicate that homogamy increased in the 2000s relative to the 1990s, but trends can vary depending on methodological choices. The increasing levels of parental wealth homogamy raise concerns that over time, partnering behavior has become more consequential for wealth inequality between couples.

BACKGROUND: While genetic variation has a known impact on the risk for obsessive-compulsive disorder (OCD), there is also evidence that there are maternal components to this risk. Here, we partitioned sources of variation, including direct genetic and maternal effects, on risk for OCD. METHODS: The study population consisted of 822,843 individuals from the Swedish Medical Birth Register, born in Sweden between January 1, 1982, and December 31, 1990, and followed for a diagnosis of OCD through December 31, 2013. Diagnostic information about OCD was obtained using the Swedish National Patient Register. RESULTS: A total of 7184 individuals in the birth cohort (0.87%) were diagnosed with OCD. After exploring various generalized linear mixed models to fit the diagnostic data, genetic maternal effects accounted for 7.6% (95% credible interval: 6.9%-8.3%) of the total variance in risk for OCD for the best model, and direct additive genetics accounted for 35% (95% credible interval: 32.3%-36.9%). These findings were robust under alternative models. CONCLUSIONS: Our results establish genetic maternal effects as influencing risk for OCD in offspring. We also show that additive genetic effects in OCD are overestimated when maternal effects are not modeled.

Seasonal migration is a complex and variable behaviour with the potential to promote reproductive isolation. In Eurasian blackcaps (Sylvia atricapilla), a migratory divide in central Europe separating populations with southwest (SW) and southeast (SE) autumn routes may facilitate isolation, and individuals using new wintering areas in Britain show divergence from Mediterranean winterers. We tracked 100 blackcaps in the wild to characterize these strategies. Blackcaps to the west and east of the divide used predominantly SW and SE directions, respectively, but close to the contact zone many individuals took intermediate (S) routes. At 14.0° E, we documented a sharp transition from SW to SE migratory directions across only 27 (10-86) km, implying a strong selection gradient across the divide. Blackcaps wintering in Britain took northwesterly migration routes from continental European breeding grounds. They originated from a surprisingly extensive area, spanning 2000 km of the breeding range. British winterers bred in sympatry with SW-bound migrants but arrived 9.8 days earlier on the breeding grounds, suggesting some potential for assortative mating by timing. Overall, our data reveal complex variation in songbird migration and suggest that selection can maintain variation in migration direction across short distances while enabling the spread of a novel strategy across a wide range.

Educational assortative mating and earnings inequality has both increased in both Europe and the United States in the last decades. As a result, educational assortative mating, or educational homogamy, has been suggested as a potential explanation for the increase in earnings inequality. According to this hypothesis increased sorting on education will lead to polarization between lower and higher-educated couples where the advantages of the latter will compound on one another and lead to increased economic inequality. The majority of the studies to date report a non-relationship between educational assortative mating and earnings inequality, one of the exceptions being a study of Denmark. This exception has led sociologists to theorize that the impact of educational assortative mating could be especially strong in the Nordic countries. In this study I test this hypothesis by employing a novel decomposition method, the Theil-index, to answer if increases in educational assortative mating are associated with increases in earnings inequality in Sweden between 2000 and 2010, using data from the Standard of Living Survey (LNU). The result is a non-relationship between homogamy and earnings inequality and an overall decrease in earnings inequality in the sample. The result is another null result for the hypothesis that educational homogamy leads to inequality, and points to a larger discrepancy between singles and couples than between couples. If corroborated, this decrease in earnings inequality would mean a divergence, in earnings inequality, between partnered individuals and the general population. Future studies should focus on the extent of this divergence.