Comments on “The absence of genotypic diversity in a successful parthenogenetic invader” by Mark Dybdahl and Devin Drown [Biological Invasions 13 (2011), 1663–1672

Abstract

We contend that a recent study of microsatellite variation in invasive populations of the New Zealand mudsnail in the United States (Dybdahl and Drown 2011) underestimated genotypic diversity because it inappropriately focused on allelic size ranges that were previously documented for (invasive) British populations. The authors ignored peaks that were “far outside” of these size ranges, thus precluding recognition of additional alleles, including those that have been reported in other populations of this species. We are also concerned about the lack of reproducibility in the scoring methods utilized because the authors did not define a threshold for deciding when peaks should be ignored. The extent to which genotypic diversity consequently has been underestimated and otherwise inaccurately described cannot be ascertained based on the data provided in this study.