Investigating the Evolution of Sexual Dimporphism via Artificial Selection and Field Experiments

Indiana University, Bloomington IN

Investigators

Abstract

0075318 Delph Some of the most conspicuous features of organisms are differences between the sexes (known as sexual dimorphism). Sexual selection is usually invoked to explain such differences and may explain dimorphism in characters that are not directly related to mate acquisition because of a cascade of genetic effects. Previous research with the dioecious plant Silene latifolia, which has remarkable sexual dimorphism in flower production, shows that individuals that produce a relatively high number of flowers have upregulated metabolisms and may pay life history costs (such as lower longevity). Artificial selection lines will be created that will have both increased and reduced sexual dimorphism in flower size and number. These lines will be planted out in experimental arrays to assess the consequences of flower production on fitness via two pathways - mating success (sexual selection) and longevity (natural selection). The combination of increasing the phenotypic variation in traits via artificial selection and subsequent field experimentation with these lines should yield great power in understanding the causes and patterns of selection. This work will help us determine whether sexual dimorphism in morphological, physiological, and life history traits has evolved via sexual selection.