by Carl Strang
I have a final study to review from last year’s scientific literature. This was reported in Science, and was interesting enough that in addition to the technical paper itself there was an interpretive article (Zuk, Marlene. 2010. Dance like no one is watching, sing like no one is listening. Science 328: 1237-1238). Frankly I thought she explained the study more clearly than did the researchers themselves (Rodríguez-Muñoz, R., A. Bretman, J. Slate et al., p.1269-1272).
They monitored a population of European field crickets, Gryllus campestris, in the field with 64 motion-sensitive and infrared-reading cameras aimed at the crickets’ burrows. All individuals were marked and their genetics known. “Both sexes mated with multiple partners, and both left more surviving offspring when they had more mates.” Males were more variable in their reproductive output than females, but not because of differences in mating rates. The variability in success thus is tied more to something else, like variable sperm quality or higher quality offspring. One surprising result was “that the vast majority of individuals, whether male or female, did not successfully reproduce at all.” Despite the females’ ability to lay dozens of eggs, none had more than 10 surviving young, and only a couple males did so. Among males, the best fighters did not have greater fitness. This is good stuff, challenging a lot of assumptions and raising interesting questions for future study.