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Resumen El objetivo del estudio es hacer un análisis descriptivo de la asociación entre la educación y la diferencia de edad entre los cónyuges en uniones de distinto sexo y conocer cómo ha evolucionado esta relación a lo largo de las cohortes en las últimas décadas a la luz del incremento del nivel educativo de la población en América Latina, en particular de las mujeres. Se hizo un análisis descriptivo utilizando muestras de rondas censales desde 1970 hasta 2010 de tres países de la región, Bolivia, Ecuador y Uruguay, seleccionando a hombres y a mujeres de 25 a 29 años de edad. Tanto en hombres como en mujeres, no se observa en general un descenso significativo de la diferencia etaria a lo largo de las cohortes. Mientras en las mujeres se observó una relación negativa entre la diferencia etaria entre cónyuges y nivel educativo, en los hombres se constató mayor heterogeneidad entre los países.

Resumo O objetivo do estudo é realizar uma análise descritiva da associação entre escolaridade e diferença de idade entre cônjuges em uniões de diferente sexo e como essa relação evoluiu ao longo das coortes nas últimas décadas em função do aumento da escolaridade da população da América Latina, especialmente para as mulheres. Foram utilizadas amostras de rodadas dos censos de 1970 a 2010 de três países da região − Bolívia, Equador e Uruguai −, selecionando homens e mulheres de 25 a 29 anos de idade. Para o total da amostra, não foi observada diminuição significativa na diferença de idade ao longo das coortes. Para as mulheres, verificou--se relação negativa entre a diferença de idade entre os cônjuges e a escolaridade. Para os homens, observou-se maior heterogeneidade entre os países.

Abstract The purpose of this study is to investigate the association between education and the age gap between spouses in heterosexual unions. The study also examines how this association has changed over time in different cohorts, especially among women, in the context of educational expansion in Latin America. The research used the data collected from census rounds conducted between 1970 and 2010 in Bolivia, Ecuador, and Uruguay. The sample included men and women aged between 25 to 29. The findings reveal that there was no significant decrease in the age difference throughout the cohorts for both men and women. However, a negative relationship was observed between the spousal age difference and educational level in women. On the other hand, men showed greater heterogeneity between countries.

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Euschistus heros (Hemiptera: Pentatomidae) has two allopatric strains with a hybrid zone in central Brazil. Asymmetric dispersal and gene flow between these strains of E. heros have been observed, where the South strain (SS) moves more quickly to the northern regions of the country than the North strain (NS) to the southern areas. In addition, SS generally has a bigger body size and presents dark brown coloration, and NS is usually smaller in size and presents light brown coloration. Here, we studied the reproductive behavior and tested for the presence of assortative mating and reproductive barriers between the two allopatric strains of E. heros. Nonrandom mating was observed in the SS strain based on mating choice trials and the reproductive isolation indexes. SS females and males prefer to mate with their co-specific (same strain) partner, while NS insects showed no mating preference. The insect's pronotum width was positively associated with the mating choice suggesting size-assortative mating in E. heros. Reciprocal crosses between strains yielded similar reproductive outputs when compared with pure strain crosses, suggesting similar fitness of hybrid pure strains. The asymmetric gene flow in the hybridization zone that favors SS seems to be associated with the reproductive behavior of the species, which favors the typical phenotype found in the SS populations.

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In this paper, we investigate how the diffusion of dual-earner couples has affected aggregate levels of inequality in Brazil. More specifically, we analyze trends in the association between spouses' earnings and assess their implications for earnings inequality among couples from 1993 to 2015. For this purpose, we use log-linear models to distinguish three components of the association between spouses' earnings: a) the correlation between spouses' earnings among dual-earner couples; b) the relationship between husbands' earnings and wives' labor force participation; and c) the proportion of dual-earner couples. Counterfactual simulations allow us to estimate how inequality would change if the trends in the association between spouses' earnings and each of its components had been different. We show that changes in the gradient of wives' employment and compositional effects related to the increasing prevalence of dual-earner couples contributed to limit the decline in inequality over the studied period.

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Anuran males and females adopt different reproductive and behavioral strategies in different contexts. We investigated the reproductive ecology and territorial behavior of the treefrog Boana goiana (B. Lutz, 1968) from the Brazilian Cerrado. We hypothesized that competitor density/proximity would increase the behavioral responses of B. goiana males, and that mating would be assortative. We also tested if the number of eggs correlates with female size and if there is a trade-off between clutch size and egg size. We conducted two territoriality experiments to test the effects of male size, competitor proximity and competitor density. Larger males called more in the presence of a second male. In the second experiment, the largest males emitted more calls and the distance to the nearest male increased as resident males called more. In both experiments, the number of calls was influenced by either male size or spacing between males. Some males behaved as satellites, probably to avoid fights. Our analyses indicate that females choose males with similar sizes to their own, corroborating our hypothesis of size-assortative mating. We found no relationships between female size and clutch size/volume, and between egg size and number of eggs per clutch. We also report multiple spawning for this species. The low incidence of physical combats and the spacing pattern indicate that this species relies almost solely on calls to resolve contests, which could be explained by low motivation, or simply because males avoid combats to decrease injury risks. Thus, acoustic or even multimodal communication seems crucial for social interactions of B. goiana.(AU)

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Anuran males and females adopt different reproductive and behavioral strategies in different contexts. We investigated the reproductive ecology and territorial behavior of the treefrog Boana goiana (B. Lutz, 1968) from the Brazilian Cerrado. We hypothesized that competitor density/proximity would increase the behavioral responses of B. goiana males, and that mating would be assortative. We also tested if the number of eggs correlates with female size and if there is a trade-off between clutch size and egg size. We conducted two territoriality experiments to test the effects of male size, competitor proximity and competitor density. Larger males called more in the presence of a second male. In the second experiment, the largest males emitted more calls and the distance to the nearest male increased as resident males called more. In both experiments, the number of calls was influenced by either male size or spacing between males. Some males behaved as satellites, probably to avoid fights. Our analyses indicate that females choose males with similar sizes to their own, corroborating our hypothesis of size-assortative mating. We found no relationships between female size and clutch size/volume, and between egg size and number of eggs per clutch. We also report multiple spawning for this species. The low incidence of physical combats and the spacing pattern indicate that this species relies almost solely on calls to resolve contests, which could be explained by low motivation, or simply because males avoid combats to decrease injury risks. Thus, acoustic or even multimodal communication seems crucial for social interactions of B. goiana.(AU)

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ABSTRACT Anuran males and females adopt different reproductive and behavioral strategies in different contexts. We investigated the reproductive ecology and territorial behavior of the treefrog Boana goiana (B. Lutz, 1968) from the Brazilian Cerrado. We hypothesized that competitor density/proximity would increase the behavioral responses of B. goiana males, and that mating would be assortative. We also tested if the number of eggs correlates with female size and if there is a trade-off between clutch size and egg size. We conducted two territoriality experiments to test the effects of male size, competitor proximity and competitor density. Larger males called more in the presence of a second male. In the second experiment, the largest males emitted more calls and the distance to the nearest male increased as resident males called more. In both experiments, the number of calls was influenced by either male size or spacing between males. Some males behaved as satellites, probably to avoid fights. Our analyses indicate that females choose males with similar sizes to their own, corroborating our hypothesis of size-assortative mating. We found no relationships between female size and clutch size/volume, and between egg size and number of eggs per clutch. We also report multiple spawning for this species. The low incidence of physical combats and the spacing pattern indicate that this species relies almost solely on calls to resolve contests, which could be explained by low motivation, or simply because males avoid combats to decrease injury risks. Thus, acoustic or even multimodal communication seems crucial for social interactions of B. goiana.

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In long-lived monogamous social species, partner compatibility can play a crucial role in reproductive success. We evaluated assortative mating based on body condition (plasma triglyceride concentration), diet (δ15N), and foraging habitat (δ13C) in the blue-footed booby Sula nebouxii, a long-lived monogamous seabird. We investigated the effects of assortative mating (sum of triglycerides in a pair) and asymmetry within pairs (residuals from regression of female-male triglycerides) on reproductive performance and offspring growth (alkaline phosphatase, ALP). We found that strong assortative mating determined by body condition and diet seemed to be related to a signalling mechanism (nutritional state). This mating pattern had a substantial effect on the breeding parameters and influenced offspring ALP. Within-pair asymmetry did not influence any reproductive parameters, but the ALP of offspring was related to the within-pair relative female condition. Overall, our results indicate that individuals seek the best possible match to maximize their breeding investment and/or individuals are limited in their mate options by their current body condition, which has consequences for offspring fitness in the short term. Our findings show that assortative mating based on body condition produces notable variation in the joint condition of the pair, which determines their breeding success.

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Abstract Marriage is an appreciated worldwide institution, although nearly half of first marriages end in divorce. Thus, the relevance of understanding how people choose their partners and what features can predict a satisfactory relationship. More specifically, in search of data supporting similarity or complementarity approaches on marital satisfaction, the current study analyzes the association between different assortative mating options (homogamy, and heterogamy) and marital satisfaction in Spanish and Dominican couples. A stratified quota sampling of 600 participants was selected, corresponding to 300 married couples (50% Spanish and 50% Dominicans). Data were gathered by means of an interview with the 10-item scale on Marital Satisfaction and a 7-item scale on Status. Results suggest that spouses are matched by similarity in their health and education and by the perception of similarity in intelligence and the financial advantages of staying together. Dominican couples experienced higher marital satisfaction than Spanish couples. Findings on hypergamy reveals the persistence of some traditional roles' distribution among Spanish speaking cultures. The association between status and marital satisfaction revealed that heterogamy rather than homogamy is associated to such satisfaction. These results stress the relevance of taking into account social and cultural differences, beyond biological and psychological factors, to fully understand couples' satisfaction.

Resumen El matrimonio es una institución apreciada a nivel mundial, pese a que casi la mitad de los primeros matrimonios terminan en divorcio. De ahí la importancia de comprender cómo las personas eligen a sus parejas y qué factores contribuyen a predecir una relación satisfactoria. Más concretamente, en busca de datos que ofrezcan apoyo a los enfoques de semejanza o de complementariedad en su relación con la satisfacción marital, el presente estudio analiza diferentes alternativas de emparejamiento selectivo (homogamia y heterogamia) y su relación con dicha satisfacción marital en parejas españolas y dominicanas. Para llevar a cabo el estudio se ha empleado un muestreo estratificado por cuotas compuesto por un total de 600 participantes, que se corresponden con 300 parejas casadas (un 50% procedente de España y el otro 50% procedente de República Dominicana). Los datos se recogieron a través de entrevista la escala de 10 ítems de Satisfacción Marital y la escala de 7 ítems de Status. Los resultados sugieren que los emparejamientos se caracterizan por la semejanza en salud, formación, inteligencia, y por la percepción compartida de las ventajas económicas asociadas a su permanencia. Las parejas dominicanas experimentan una mayor satisfacción marital que las españolas. Los resultados obtenidos sobre hipergamia revelan la persistencia de una distribución de roles tradicional en países de habla hispana. La asociación entre estatus y satisfacción marital indicaron que la heterogamia más que la homogamia, se asocia a tal satisfacción. Todos estos resultados subrayan la importancia de tener en cuenta diferencias sociales y culturales, además de factores biológicos y psicológicos, para comprender plenamente la satisfacción en las parejas.

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Global biodiversity is being degraded at an unprecedented rate, so it is important to preserve the potential for future speciation. Providing for the future requires understanding speciation as a contemporary ecological process. Phylogenetically young adaptive radiations are a good choice for detailed study because diversification is ongoing. A key question is how incipient species become reproductively isolated from each other. Barriers to gene exchange have been investigated experimentally in the laboratory and in the field, but little information exists from the quantitative study of mating patterns in nature. Although the degree to which genetic variation underlying mate-preference learning is unknown, we provide evidence that two species of Darwin's finches imprint on morphological cues of their parents and mate assortatively. Statistical evidence of presumed imprinting is stronger for sons than for daughters and is stronger for imprinting on fathers than on mothers. In combination, morphology and species-specific song learned from the father constitute a barrier to interbreeding. The barrier becomes stronger the more the species diverge morphologically and ecologically. It occasionally breaks down, and the species hybridize. Hybridization is most likely to happen when species are similar to each other in adaptive morphological traits, e.g., body size and beak size and shape. Hybridization can lead to the formation of a new species reproductively isolated from the parental species as a result of sexual imprinting. Conservation of sufficiently diverse natural habitat is needed to sustain a large sample of extant biota and preserve the potential for future speciation.

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Mendelian randomization (MR) has been increasingly used to strengthen causal inference in observational epidemiology. Methodological developments in the field allow detecting and/or adjusting for different potential sources of bias, mainly bias due to horizontal pleiotropy (or "off-target" genetic effects). Another potential source of bias is nonrandom matching between spouses (i.e., assortative mating). In this study, we performed simulations to investigate the bias caused in MR by assortative mating. We found that bias can arise due to either cross-trait assortative mating (i.e., assortment on two phenotypes, such as highly educated women selecting taller men) or single-trait assortative mating (i.e., assortment on a single phenotype), even if the exposure and outcome phenotypes are not the phenotypes under assortment. The simulations also indicate that bias due to assortative mating accumulates over generations and that MR methods robust to horizontal pleiotropy are also affected by this bias. Finally, we show that genetic data from mother-father-offspring trios can be used to detect and correct for this bias.

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Neutral models of speciation based on isolation by distance and assortative mating, termed topopatric, have shown to be successful in describing abundance distributions and species-area relationships. Previous works have considered this type of process in the context of haploid genomes. Here we discuss the implementation of two schemes of dominance to analyze the effects of diploidy: a complete dominance model in which one allele dominates over the other and a perfect codominant model in which heterozygous genotypes give rise to a third phenotype. In the case of complete dominance, we observe that speciation requires stronger spatial inbreeding in comparison to the haploid model. For perfect codominance, instead, speciation demands stronger genetic assortativeness. Nevertheless, once speciation is established, the three models predict the same abundance distributions even at the quantitative level, revealing the robustness of the original mechanism to describe biodiversity features.

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Nonrandom mating in human populations has important implications for genetics and medicine as well as for economics and sociology. In this study, we performed an integrative analysis of a large cohort of Mexican and Puerto Rican couples using detailed socioeconomic attributes and genotypes. We found that in ethnically homogeneous Latino communities, partners are significantly more similar in their genomic ancestries than expected by chance. Consistent with this, we also found that partners are more closely related--equivalent to between third and fourth cousins in Mexicans and Puerto Ricans--than matched random male-female pairs. Our analysis showed that this genomic ancestry similarity cannot be explained by the standard socioeconomic measurables alone. Strikingly, the assortment of genomic ancestry in couples was consistently stronger than even the assortment of education. We found enriched correlation of partners' genotypes at genes known to be involved in facial development. We replicated our results across multiple geographic locations. We discuss the implications of assortment and assortment-specific loci on disease dynamics and disease mapping methods in Latinos.

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Esse artigo tem por objetivo analisar os padrões de seletividade marital entre os casais heterossexuais e os casais homossexuais no Brasil, investigando os níveis de escolaridade, cor/raça e grupo etário. Inicialmente foi feita uma análise descritiva dos dados com o intuito de caracterizar a população estudada e os diferenciais entre os tipos de casais. Além disso, esse artigo utiliza tabelas de contingência e modelos log-lineares para compreender as formas de associações entre os casais e quais variáveis influenciam a seletividade dos parceiros. Os resultados mostram que cor/raça e escolaridade têm maior influência na seletividade dos casais heterossexuais, enquanto cor/raça e grupo etário são mais relevantes para os casais homossexuais em relação aos seus padrões de seletividade. Portanto, é possível identificar a existência de diferenças entre as características de seletividade entre esses casais e seus padrões, o que abre margem para estudos posteriores que possam aprofundar a compreensão das distinções entre esses padrões, no sentido de encontrar formas de tentar explicá-las e suas possíveis consequências no Brasil.

El objetivo de este artículo es analizar los patrones de selectividad marital entre las parejas heterosexuales y homosexuales en Brasil, investigando para ello los niveles de escolaridad, color/raza y grupo etario. Inicialmente se realizó un análisis descriptivo de los datos con el fin de caracterizar a la población estudiada y los diferenciales entre los tipos de parejas. Además, el estudio utiliza tablas de contingencia y modelos log-lineares para entender las formas de asociación entre las parejas y las variables que influyen en la selectividad de sus miembros. En relación con los patrones de selectividad, los resultados muestran que el color/raza y la escolaridad tienen mayor influencia en las parejas heterosexuales, mientras que el color/raza y el grupo etario al que se pertenece son más relevantes para las parejas homosexuales. Por lo tanto, se pueden identificar diferencias entre las características de la selectividad de estas parejas y sus patrones, lo que abre un espacio para estudios posteriores que puedan profundizar la comprensión de las diferencias entre estos patrones, con el fin de intentar explicar estas distinciones y sus posibles consecuencias en el país.

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Past and present attempts to classify and characterize the human biological variability are examined, considering the race concept, ethnic identification problems, assortative mating based on ethnicity, and historical genetics. In relation to the latter, a review is made of the methods presently available for admixture quantification and of previous studies aimed at the characterization of the parental continental contributions to Latin American populations, with emphasis in global evaluations of the Costa Rican and Brazilian gene pools. Finally, the question of racism and discrimination is considered, including the relation between human rights and affirmative actions. The right to equal opportunity should be strictly respected. Biological inequality has nothing to do with the ethical principle that someone's position in a given society should be an accurate reflection of her/his individual ability.

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