An estimate of the relative opportunities for natural and sexual selection in a population of milkweed beetles.

Abstract

The two sexes were very similar with respect to the means and distributions of survivorship and mating success. Total fitness in males was defined as the product of the proportion of recaptures in which an individual was observed mating and the total amount of time (adult lifespan) available for mating. The opportunity for selection in this population of males was calculated from the distribution of fitnesses among individuals. The opportunity for selection was further broken down into natural selection due to variance in lifespan and sexual selection due to variance in the ability to acquire a mate during a short subset of total lifespan (mating efficiency). Variance in lifespan provides over 2 times more opportunity for selection than does variance in mating efficiency. -from Author