Cryptic Sex-Ratio Bias Provides Indirect Genetic Benefits Despite Sexual Conflict

Anolis sagrei, was used in the study to demonstrate that sex-ratio bias can provide indirect genetic benefits despite sexual conflict

Two scientists from Dartmouth College have demonstrated a counterpoint to the long-held belief that sexual dimorphism causes high-fitness parents often to produce low-fitness progeny of the opposite sex.  According to the authors, this alleviates the evolutionary costs incurred, restoring the benefits of mate choice.

The article, by Robert M. Cox and Ryan Calsbeek, was published April 2, online in the journal Science.  Below is the abstract from the article.  To read the entire article (if you have a subscription), please click on the following URL:
http://www.sciencemag.org/cgi/content/abstract/sci;328/5974/92?maxtoshow=&hits=10&RESULTFORMAT=&fulltext=evolution&searchid=1&FIRSTINDEX=0&sortspec=date&resourcetype=HWCIT.

Abstract

When selection favors sexual dimorphism, high-fitness parents often produce low-fitness progeny of the opposite sex. This sexual conflict is thought to overwhelm the genetic benefits of mate choice because preferred males incur a cost through the production of low-fitness daughters. We provide a counterpoint in a lizard (Anolis sagrei) that exhibits sexual conflict over body size. By using mate-choice experiments, we show that female brown anoles produce more sons than daughters via large sires but more daughters than sons via small sires. Measures of progeny fitness in the wild suggest that maximal fitness payoffs can be achieved by shifting offspring production from daughters to sons as sire size increases. These results illustrate how the resolution of sexual conflict can restore the genetic benefits of mate choice.