Anolis sagrei mating. Taken from the Cox lab website.

Anolis sagrei mating. Taken from the Cox lab website.

On the first day of SICB 2015 Robert Cox gave an interesting talk about reproductive investment and sexual selection in lizards. At the center of his talk was the striking notion that males and females are different biologically, yet should still be integrated into cohesive theories of sexual selection. According to Dr. Cox, past theory has generated mutually exclusive ideas about the costs of reproduction for each sex. Whereas theories about females have focused on life history and investment in the egg and offspring, theories about males have focused on mating investment. Cox stressed that this is overly simplified and doesn’t reflect biological reality,  as males and females also share many of the same costs of reproduction as well. Issues like growth, survivorship, energy storage, and parasite load are shared between the sexes. Dr. Cox is now trying to test how sex-specific reproductive mechanisms affect these shared reproductive constraints by surgically removing the gonads of each sex. Preliminary analyses show that parasite load appears to be a shared effect among the sexes regardless of the underlying mechanism (testosterone derived from testes versus estrogen derived from the ovaries). Studies directly comparing the underlying mechanisms of sexual dimorphic anatomy, physiology, and behavior are critical for the further development of sexual selection theory and for improving our understanding of anoles. Studies like Dr. Cox’s are an important step in that direction.

 

Latest posts by Thomas Sanger (see all)