Major histocompatibility antigens and spontaneous abortion: an evolutionary perspective.

Maternal-fetal histocompatibility as a consequence of sharing of MHC antigens between males and females may result in an increased incidence of spontaneous abortion. We propose that such a response may be of evolutionary significance in inbred populations where partners that are similar at MHC loci also are likely to share deleterious recessive alleles due to common descent. In this scenario, spontaneous abortion is regarded as an adaptive response on behalf of the mother, who terminates at an early stage her investment in an offspring which would likely be of low reproductive value if carried to term.

Correspondence between sexual isolation and allozyme differentiation: a test in the salamander Desmognathus ochrophaeus.

Ethological reproductive isolation and genetic divergence across 26 protein loci were measured among populations of the salamander Desmognathus ochrophaeus in the southern Appalachian Mountains. Levels of ethological isolation varied from none to complete and were statistically significant for all but two pairings between populations inhabiting different mountain ranges. When geographic and genetic distances were treated as independent variables in multiple correlation analyses, they accounted for about half the variance in levels of ethological isolation. When genetic distance is held constant, the remaining relationship between ethological isolation and geographic distance is still statistically significant. When geographic distance is held constant, the remaining relationship between genetic distance and levels of ethological isolation is nonsignificant, as is the relationship between geographic distance and genetic distance when ethological isolation is held constant. Ethological isolation and genetic divergence evidently both reflect the gradual divergence of allopatric populations, but genetic distance is a poor predictor of ethological isolation in these salamanders.