The Origin and Evolution of Parthenogenesis in Heteronotia Binoei (Gekkonidae): Reciprocal Origins and Diverse Mitochondrial DNA in Western Populations

Abstract

Parthenogenetic lines of the Heteronotia binoei complex are genetically diverse, of hybrid origin, and geographically widespread, ranging from central Australia to the west coast. Analysis of the western populations revealed a class of mitochondrial DNA (mtDNA) approximately 12% different from the mtDNAs found among parthenogens further east. Detailed analysis of mtDNAs from 59 western individuals revealed far greater diversity than previously reported for any parthenogenetic vertebrate. Phylogenetic comparisons with mtDNAs from the bisexual parental species identified the maternal parent(s) as coming from the SM6 species, most probably from west coast populations. This ancestry contrasts with that of the more eastern parthenogenetic lines, which had as parents females of the other bisexual parental species, CA6. The nucleotide diversity of mtDNA among the western parthenogens, although higher than usual (x̄ = 0.38%), is low compared with the variation found within (2.1%) and among (3.9–7.8%) SM6 populations. This diversity illustrates the importance of rigorous sampling of related bisexual populations for interpreting variation among unisexuals. Despite the high mtDNA diversity, these parthenogens probably arose from a relatively small geographic area. The distinct geographic ranges of parthenogens that have the two major classes of mtDNA suggest that the western populations arose separately and further to the west than did the other lines. If so, then the two groups of parthenogenetic lines should be regarded as separate species.