MHC-dependent mate choice in humans: why genomic patterns from the HapMap European American dataset support the hypothesis

The role of the major histocompatibility complex (MHC) in mate choice in humans is controversial. Nowadays, the availability of genetic variation data at genomic scales allows for a careful assessment of this question. In 2008, Chaix et al. reported evidence for MHC-dependent mate choice among European American spouses from the HapMap 2 dataset. Recently, Derti et al. suggested that this observation was not robust. Furthermore, when Derti et al. applied similar analyses to the HapMap 3 European American samples, they did not see a significant effect. Although some of the points raised by Derti et al. are relevant, we disagree with the reported absence of evidence for MHC-dependent mate choice within the HapMap samples. More precisely, we show here that the MHC dissimilarity among HapMap 3 European American spouses is still extreme in comparison to the rest of the genome, even after multiple testing correction. This finding supports the hypothesis of MHC-dependent mate choice in some human populations.     

Reproduction and Hybridisation in the Genus Rosa,Section Caninae (Ser.) Rehd.

Crossing experiments were carried out in order to investigate the importance of apogamy in relation to autogamy, geitonogamy and xenogamy in the reproductive biology of pentaploid members of the genus Rosa, section Caninae (Ser.) Rehd. About 10,000 seeds from 900 crossing experiments were examined, 4500 of them for both filling of the grain and viability of the embryo. The results were compared with experimental reports and literature dating from 1753 to 1995. Apomictic reproduction was shown to be possible in all species of the section tested, but viable seed yields were only about 5% of those produced by xenogamy. This contradicts the hypothesis of Fagerlind (1940,1944,1945,1950) and Custafsson and Hakansson (1942), but supports the results of Matsson (1912) and Schwertschlager (1915). The number of viable seeds increased in the order apogamy, autogamy, geitonogamy to xenogamy. Reciprocal crossings showed significant differences in the number of seeds produced in the hip. This contradicts the hypothesis on the genomic constitution of the pentaploid Caninae with unbalanced heterogamy, as advocated by Hurst (1927) and Custafsson and Hakansson (1942).     

Ethnic heterogamy and the risk of partner violence in Mexico

A common stereotype holds that in Mexico male violence toward women is common among indigenous peoples and reflects cultural norms that sanction a male's domination of his female partner. We employ a recent Mexican survey to examine the relative risk of violence against women as a function of the couple's ethnic homogamy. Among couples in which both partners are either non-indigenous or indigenous the female's risk of partner violence is similar. Among heterogamous couples non-indigenous females in relationships in which the male is indigenous are at elevated risk of violence, while indigenous women in relationships with non-indigenous males are at a lower risk of violence. The stresses associated with heterogamy appear to be more salient in determining a woman's risk of violence than ethnicity per se. The implications for future research and the need to deal with the issue of ethnic homogamy in culturally heterogeneous populations are discussed.