Abstracts (first author)
Tests of life-history theory under self- and cross-fertilization in Caenorhabditis elegans
In organisms that are able to reproduce by self-fertilization (selfing) and by cross-fertilization (outcrossing), a fitness trade-off between both reproduction modes is necessary for them to be maintained during evolution. To assess if the maintenance of selfing and outcrossing at intermediate frequencies is in part due to the evolution of resource allocation towards the male or the female functions in hermaphrodites, we performed experimental evolution in Caenorhabditis elegans, an androdioecious nematode in which hermaphrodites are self-fertile but can also be cross-fertilized by males. For this, we characterized the reproductive schedules and the longevity of hermaphrodites under selfing or outcrossing with males that did not have the opportunity to evolve with them. Hermaphrodite life-history was compared to that of females, which evolved under similar environmental conditions but with obligate outcrossing. After 100 generations of evolution, the reproductive investment of hermaphrodites when selfed was shifted towards earlier ages, as expected with selection for early reproduction, together with an increase in mean longevity. When hermaphrodites were outcrossed no such changes in reproductive investment or longevity were observed. Like selfed hermaphrodites however, females from the obligate outcrossing populations showed increased earlier reproductive investment and increased longevity. These findings suggest that the fitness trade-off between selfing and outcrossing in experimental C. elegans populations is due to the evolution of resource allocation towards male functions in hermaphrodites.