Mate choice preference

Although the mechanism for HLA-based mate choice in humans is not known, MHC-based mate choice preferences in rodents are olfactory mediated (reviewed in Alberts Ober, 1993). In humans, evidence for MHC-based olfactory recognition has recently been presented by Wedekind and colleagues (Wedekind et. al., 1995, 1997). Despite the methodological limitations of these studies (Hedrick and Loeschcke, 1996), the results are consistent with the data from rodent studies and suggest that humans may indeed use olfactory cues to discriminate between persons similar and dissimilar in the MHC. This premise has been bolstered recently by the identification of a family of olfactory receptor genes (OLF) that map within the human MHC (Fan et al., 1996), but additional studies are needed to determine whether preferences for mates with dissimilar HLA haplotypes in the Hutterites are indeed mediated by olfactory cues. 

Wolfenbarger, L. L. 1999c. Female mate choice in northern cardinals Is there a preference for redder males Wilson Bull. Ill 76-83. 

D Udine, B. a. A., E. (1983) Early experience and sexual preferences in rodents. In P. Bateson (Ed.), Mate Choice. Cambridge University Press, Cambridge, pp. 311-327. 

While mate choice for unfamiliar partners might be explained by the fitness benefits of multiple mating, inbreeding avoidance, and favouring rare genotypes, preference for familiar males is also sometimes observed. Why would females choose relatively familiar males as mates, given the benefits outlined above of avoiding such males ... 

Meadow vole Anal gland, urine, feces Protein, 9,15 or 25% Mate choice voles with high-protein diet preferred... 

Coleoptera. A recent work on chrysomelidae (Peterson et al., 2007) evaluated the evolution of sexual isolation between two leaf beetles, Chrysochus cobaltinus and C. auratus, in a hybrid zone in Washington state (USA). By painting beetle cadavers with various cuticular extracts, the authors demonstrated a strong male preference for conspecific females according to species and sexual chemical specificity of their respective cuticular hydrocarbon profiles. This male mate choice reinforced sexual isolation. 

Crabs without burrows orient to and hide against objects on the surface to reduce their predation risk. Females leave their burrows and search for mates by visiting several courting males at their burrows before they choose one. Males sometimes build structures at the entrances to their burrows. Females are more attracted to burrows with than without structures and this preference increases with perceived predation risk. The preference reduces females predation risk and incidentally biases mate choice in favor of males with structures... 

In some mate choice studies, urine is presented in place of the whole animal in order to demonstrate that odours are, or can be, mediators of disassortative mating (e.g. Ninomiya and Brown, 1995 Ehman and Scott, 2001). In the absence of more direct measures, such as asking human subjects which odour they prefer (e.g. Wedekind et al., 1995), the duration of investigation or time spent near an odour are generally assumed to equate directly to preference. This can be misleading when the assumption is not explicitly tested. For instance, female voles have been shown to exhibit an odour preference for unparasitized males which does not correlate with mate selection (Klein et al., 1999). 

Recent research has shown that among humans MHC type plays a role in the selection of heterosexual mates. Studies on the North American Hutterite community (a reproductively isolated, cultural and religious group of Austrian ancestry) revealed that mate choice was influenced by an avoidance of spouses with a high degree of haplotype overlap with self (Ober, this volume). In another study, Wedekind, Seebeck, Bettens and Paepke (1995), typed female and male students for their MHC haplotypes. Each male subject wore a T-shirt for two consecutive nights, after which the T-shirts were collected and placed in identical cardboard boxes for the female subjects to sniff and evaluate. For each female, half of the boxes contained T-shirts from men who were similar to her in MHC-type, and half contained T-shirts from men who were dissimilar. The results revealed that females who were not on birth control pills preferred the smell of males who were most dissimilar from them in MHC-type, indicating that female preferences for male body odor correlates with MHC dissimilarity. These women also reported that the body odor of the males they preferred reminded them of their current and/or ex-mates. Thus, as with rodents, human mate selection appears to be related to female preferences for male body odors that correlate with MHC dissimilarity (complementarity). 

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