Development of microsatellite markers for the geographically parthenogenetic stick insect Phraortes elongatus...

Many plant and animal species exhibit geographic parthenogenesis, wherein unisexual (= parthenogenetic) lineages are more common in their marginal habitats such as high latitude or altitudes than their closely related bisexual counterparts. The Japanese stick insect, Phraortes elongatus (Thunberg) (Insecta: Phasmatodea), is known as a geographically parthenogenetic species due to the existence of both bisexual and unisexual populations. Here, we developed microsatellite markers to infer the genetic variation among populations of P. elongatus. Totally, 13 primer pairs were developed for the species, and they were tested on 47 samples collected from both a bisexual population and a unisexual population. All 13 loci were polymorphic in the bisexual population, whereas no loci were polymorphic in the unisexual population. The loss of variation in the unisexual population implies automixis with terminal fusion or gamete duplication as the mode of parthenogenesis. The markers developed in this study will be helpful for further comprehensive analysis of the genetic diversity and gene flow between bisexual and parthenogenetic lineages of P. elongatus.