RELATING HYBRID ADVANTAGE AND GENOME REPLACEMENT IN UNISEXUAL SALAMANDERS
Article first published online: 29 DEC 2011
© 2011 The Author. Evolution© 2011 The Society for the Study of Evolution.
Volume 66, Issue 5, pages 1387–1397, May 2012
How to Cite
Charney, N. D. (2012), RELATING HYBRID ADVANTAGE AND GENOME REPLACEMENT IN UNISEXUAL SALAMANDERS. Evolution, 66: 1387–1397. doi: 10.1111/j.1558-5646.2011.01523.x
- Issue published online: 20 APR 2012
- Article first published online: 29 DEC 2011
- Accepted manuscript online: 29 NOV 2011 06:42AM EST
- Received May 1, 2011 , Accepted November 13, 2011
Unisexual vertebrates are model systems for understanding the evolution of sex. Many predominantly clonal lineages allow occasional genetic recombination, which may be sufficient to avoid the accumulation of deleterious mutations and parasites. Introgression of paternal DNA into an all-female lineage represents a one-way flow of genetic material. Over many generations, this could result in complete replacement of the unisexual genomes by those of the donor species. The process of genome replacement may be counteracted by contemporary dispersal or by positive selection on hybrid nuclear genomes in ecotones. I present a conceptual model that relates nuclear genome replacement, positive selection on hybrids and biogeography in unisexual systems. I execute an individual-based simulation of the fate of hybrid genotypes in contact with a single host species. I parameterize these models for unisexual salamanders in the Ambystoma genus, for which the frequency of genome replacement has been a source of ongoing debate. I find that, if genome replacement occurs at a rate greater than 1/10,000 in Ambystoma, then there must be compensating positive selection in order to maintain observed levels of hybrid nuclei. Future researchers studying unisexual systems may use this framework as a guide to evaluating the hybrid superiority hypothesis.