Distorting sex ratios

Distorting sex ratios.

D uring sperm production in mammals, the process of meiosis generates sper-matozoa that are genetically different but functionally equivalent. So, with respect to the sex chromosomes, for example, equal numbers of sperm are produced carrying either an X or a Y chromosome. Because X and Y sperm are equally capable of fertilizing an egg, equal numbers of male and female embryos are produced, and ...

Sex ratios.

Jennions et al. introduce the different kinds of sex ratio and their biology.

Sex Determination, Sex Ratios and Genetic Conflict

Genetic mechanisms of sex determination are unexpectedly diverse and change rapidly during evolution. We review the role of genetic conflict as the driving force behind this diversity and turnover. Genetic conflict occurs when different components of a genetic system are subject to selection in opposite directions. Conflict may occur between genomes (including paternal-maternal and parentalzygo...

Sex-ratio-distorting Wolbachia causes sex-role reversal in its butterfly host.

Sex-role-reversed mating systems in which females compete for males and males may be choosy are usually associated with males investing more than females in offspring. We report that sex-role reversal may also be caused by selfish genetic elements which distort the sex ratio towards females. Some populations of the butterflies Acraea encedon and Acraea encedana are extremely female biased becau...

Sex ratios in primate groups