OUTBREEDING DEPRESSION WITH LOW GENETIC VARIATION IN SELFING CAENORHABDITIS NEMATODES |
| |
Authors: | Clotilde Gimond Richard Jovelin Shery Han Céline Ferrari Asher D Cutter Christian Braendle |
| |
Institution: | 1. Institut de Biologie Valrose, , CNRS UMR7277 Parc Valrose, France;2. INSERM U1091, , France;3. Université Nice Sophia Antipolis, UFR Sciences, , France;4. Department of Ecology and Evolutionary Biology, University of Toronto, , Toronto, Ontario, M5S 3B2 Canada |
| |
Abstract: | Theory and empirical study produce clear links between mating system evolution and inbreeding depression. The connections between mating systems and outbreeding depression, whereby fitness is reduced in crosses of less related individuals, however, are less well defined. Here we investigate inbreeding and outbreeding depression in self‐fertile androdioecious nematodes, focusing on Caenorhabditis sp. 11. We quantify nucleotide polymorphism for nine nuclear loci for strains throughout its tropical range, and find some evidence of genetic differentiation despite the lowest sequence diversity observed in this genus. Controlled crosses between strains from geographically separated regions show strong outbreeding depression, with reproductive output of F1s reduced by 36% on average. Outbreeding depression is therefore common in self‐fertilizing Caenorhabditis species, each of which evolved androdioecious selfing hermaphroditism independently, but appears strongest in C. sp. 11. Moreover, the poor mating efficiency of androdioecious males extends to C. sp. 11. We propose that self‐fertilization is a key driver of outbreeding depression, but that it need not evolve as a direct result of local adaptation per se. Our verbal model of this process highlights the need for formal theory, and C. sp. 11 provides a convenient system for testing the genetic mechanisms that cause outbreeding depression, negative epistasis, and incipient speciation. |
| |
Keywords: | Androdioecy C sp 11 C briggsae C elegans genetic diversity genetic incompatibilities |
|
|