Spatio-Temporal Patterns of Hybridization in an Alloploid Salamander (Ambystomatidae: ) and Conservation Implications of Introgression in a Unisexual Vertebrate.

Maynard Smith's proposed two-fold cost of sex states that one of the disadvantages of clonal reproduction is the decreased ability to persist in dynamic ecosystems. However, the long-term persistence of some clonal alloploid lineages suggests that these lineages may not always be so ephemeral in nature. Understanding the stability of these lineages over time can inform our understanding of the advantages of an asexual mode of life. Here we investigate a gynogenetic allopolyploid triploid, the Silvery Salamander (LJJ-historically referred to as ), an asexual lineage closely related to . However, in our focal populations, neither parental species is present, and another sexual host, (TT), is a required sperm donor. Gynogenetic reproduction involving LJJ and its host should result in a clone of the mother (LJJ); however, with the occurrence of kleptogenesis, it often can result in tetraploid hybrids (LJJT). LJJ is considered endangered in this population due to its restricted range coupled with concerns that the cryptic tetraploid (LJJT) could completely replace LJJ. Here we assess the level of LJJ ×  hybridization in nine ephemeral wetland populations in east central Illinois. Using species-specific microsatellite loci, we compared the prevalence of LJJ and LJJT genotypes across localities and years. We find variation across ponds and developmental stages but suggest relative stability over time. Given the considerable amount of environmental degradation and loss, we suggest continued monitoring of this unique segment of biodiversity to ensure its persistence into the future.