Biodiversity Through Sexual Selection

What engenders biodiversity? Natural selection certainly adapts species to their ecological niches, but does it really create all of the new niches and new species to ll them? Consider: the most successful, complex, and numerous species on earth are composed of sexually-reproducing animals and owering plants. Both groups typically undergo a form of sexual selection through mate choice: animals are selected by conspeci cs and owering plants are selected by heterospeci c pollinators. This common feature suggests that the evolution of biodiversity may be driven not simply by natural-selective adaptation to ecological niches, but by subtle interactions between natural selection and sexual selection. This paper presents theoretical arguments and simulation results in support of our view that sexual selection creates new tness peaks (and thus new niches), helps species escape from old local optima to nd new, better peaks, and promotes speciation to increase the number of lineages searching for peaks. Natural selection is a precondition for biodiversity (because it permits ecological adaptation), but sexual selection may often be a more direct cause of species diversity for animals and owering plants. The paper concludes with implications for evolutionary engineering, human evolution, and conservation priorities.