Sex Ratios: Safe's Response

Sex ratios.

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

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 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...

Reproducing lizards modify sex allocation in response to operational sex ratios.

Sex-allocation theory suggests that selection may favour maternal skewing of offspring sex ratios if the fitness return from producing a son differs from that for producing a daughter. The operational sex ratio (OSR) may provide information about this potential fitness differential. Previous studies have reached conflicting conclusions about whether or not OSR influences sex allocation in vivip...

Sex ratios in primate groups