Dimorphism: takes two
Steve Chenoweth is suggesting a radical idea: females may also be targeted by sexual selection. Chenoweth has been studying sexual dimorphism in Australian fruit flies (Drosophila serrata), in both laboratory-manipulated and wild-caught populations. Contrary to the common perception of males as the evolutionary scratchpad, Chenoweth's team found that females, not males, responded to sexual selection (ScienceDaily, 2008). Chenoweth published last year (with Foley et al, 2007) that although both male and female Drosophila melanogaster use pheromones (created from the same base compound) to attract mates, the genetic control of these pheromones seems to be different for males and females.
An interesting gender difference noted by Chenoweth is in the difference between mate-selection traits between male and female fruit flies. Chenoweth et al (2006) found what they called "exaggerated male traits" -- traits that led to sexual selection even when they were exerting negative survival selection. In contrast, Chenoweth et al (2007) found that male sexual selection was a "stabilizing" rather than "directional" influence. The researchers admit that the male flies may be using different markers of fecundity than were manipulated.
Wait, so females choose the exaggerated male form, but males prefer a realistic body type? Well, I guess there are differences between fruit flies and humans. I'm back from two weeks in Vegas, and I've seen enough exaggerated female form to last me several months. I recognize that I'm falling prey to a culturally-informed anthropomorphic world-view here, but I'm having a really hard time with believing that any male's tastes, of any species, have stabilizing effects. I find this a nonsensical statement, but maybe I'm not giving the fruit flies enough credit?
An interesting gender difference noted by Chenoweth is in the difference between mate-selection traits between male and female fruit flies. Chenoweth et al (2006) found what they called "exaggerated male traits" -- traits that led to sexual selection even when they were exerting negative survival selection. In contrast, Chenoweth et al (2007) found that male sexual selection was a "stabilizing" rather than "directional" influence. The researchers admit that the male flies may be using different markers of fecundity than were manipulated.
Wait, so females choose the exaggerated male form, but males prefer a realistic body type? Well, I guess there are differences between fruit flies and humans. I'm back from two weeks in Vegas, and I've seen enough exaggerated female form to last me several months. I recognize that I'm falling prey to a culturally-informed anthropomorphic world-view here, but I'm having a really hard time with believing that any male's tastes, of any species, have stabilizing effects. I find this a nonsensical statement, but maybe I'm not giving the fruit flies enough credit?