Lab-meeting on Tuesday 9 March at 13.00 on sexual dimorphism and sex-specific selection

Lab-meeting this coming week will be on Tuesday afternoon (13.00-15.00), not on our usual time on Wednesday mornings. We will discuss a recent paper in Evolution by our Dartmouth colleagues Robert Cox and Ryan Calsbeek on sexual size dimorphism and sex-specific selection in Anolis-lizards:

SEX-SPECIFIC SELECTION AND INTRASPECIFIC VARIATION IN SEXUAL SIZE DIMORPHISM Robert M. Cox and Ryan Calsbeek Sexual size dimorphism (SSD) is thought to evolve due to sex differences in selection on body size, but it is largely unknown whether intraspecific variation in SSD reflects differences in sex-specific selection among populations. We addressed this question by comparing viability selection between two island populations of the brown anole lizard (Anolis sagrei) that differ in the magnitude of male-biased SSD. On both islands, females experienced stabilizing selection favoring intermediate size whereas males experienced directional selection favoring larger size. Thus, sex-specific selection matched the overall pattern of male-biased SSD, but population differences in the magnitude of SSD were not associated with local differences in selection. Rather, population differences in SSD appear to result from underlying differences in the environmental potential for a rapid growth, coupled with sex-specific phenotypic plasticity. Males grew more slowly on the island with low SSD whereas growth of females did not differ between islands. Both sexes had substantially lower mass per unit length on the island with low SSD, suggesting that they were in a relatively poorer energetic condition. We propose that this energetic constraint disproportionately impacts growth of males due to their greater absolute energy requirements, thus driving intraspecific variation in SSD.

This paper should be of interest because of its links to sexual conflict, and incidentally, Bob and Ryan also has a Science-paper that will soon come out on how females manipulate offspring sex depending on the sire's body size in an adaptive fashion, i. e. a resolution of intralocus sexual conflict that you can read more about in this previous blogpost on one of my recent papers on another lizard species (Uta stansburiana).

When to meet? Tuesday March 9, 13.00
Where: "Darwin" room, 2nd floor, Ecology Building

Any fika-volunteer?