Many theories have been proposed to explain the evolution of sex, but the question remains unsettled owing to a paucity of compelling empirical tests. The crux of the problem is to understand the prevalence of sexual reproduction in the natural world, despite obvious costs relative to asexual reproduction. Here we perform experiments with digital organisms (evolving computer programs) to test t...

In the United States, the greenbug, Schizaphis graminum (Rondani), reproduces primarily by apomictic parthenogenesis. Although a periodic sexual cycle exists, the extent to which it occurs naturally and its influence on the genetic variability of greenbug populations is unclear. Length variation in the intergenic spacer (IGS) of the rRNA cistron in the greenbug indicates that populations are ma...

Sex is by far the most predominant mode of reproduction among eukaryotes. Nevertheless, two new discoveries of asexual reproduction in a lizard and a plant from the Australian arid zone highlight an emerging trend toward the loss of sex in this region. Efforts to understand the processes leading to this pattern should provide important information about the relative advantages and disadvantages...

It is commonly assumed that path integration is based on an extrinsic measure of the objective distance traversed during locomotion. In contrast, biological odometers may rely on embodied intrinsic measures, such as idiothetic information specific to an action mode. We investigated this question using a distance reproduction task in which participants traveled an outbound distance and then repr...