High Genetic Diversity Despite the Potential for Stepping-Stone Colonizations in an Invasive Species of Gecko on Moorea, French Polynesia

Maria A Tonione,Craig C Moritz,Natalie Reeder,Neil John Gemmell

doi:10.1371/journal.pone.0026874

Maria A Tonione, Craig C Moritz + Show 2 more

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https://doi.org/10.1371/journal.pone.0026874

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Abstract

Invasive species often have reduced genetic diversity, but the opposite can be true if there have been multiple introductions and genetic admixture. Reduced diversity is most likely soon after establishment, in remote locations, when there is lower propagule pressure and with stepping-stone colonizations. The common house gecko (Hemidactylus frenatus) was introduced to Moorea, French Polynesia in the remote eastern Pacific within the last two decades and accordingly is expected to exhibit low diversity. In contrast, we show that H. frenatus on Moorea has exceptionally high genetic diversity, similar to that near the native range in Asia and much higher than reported for other Pacific island reptiles. The high diversity in this recently founded population likely reflects extensive genetic admixture in source population(s) and a life history that promotes retention of diversity. These observations point to the importance of understanding range-wide dynamics of genetic admixture in highly invasive species.

Highlights

Among the most important causes of native-species extinctions is interaction with invasive species [1]
Considerable effort has been expended on genetic analyses of invasive species to infer invasion history, the dynamics of genetic diversity, and how this might contribute to potential to adapt to and thrive within nonnative habitats [2]–[4]
Distribution on Moorea Since its arrival no more than 22 years ago, H. frenatus has dispersed to occupy dwellings and other man-made structures in high numbers around the entire perimeter of the island; in contrast, no individuals of this highly conspicuous species were detected in repeated surveys of the interior forest (Fig. 1A)

Summary

Introduction

Among the most important causes of native-species extinctions is interaction with invasive species [1]. Multiple introductions involving divergent source populations can increase genetic diversity in invasive populations and promote evolutionary flexibility and the rate of spread [9]–[13] The latter outcome depends on high propagule pressure (i.e. geographic proximity to diverse source populations and/or location on transport routes; [14]) and often takes time to develop [3], [9]. The former outcome, reduced diversity, is more probable in recently colonized and geographically remote locations, especially if there have been sequential founder events associated with a stepping-stone colonization process The former outcome, reduced diversity, is more probable in recently colonized and geographically remote locations, especially if there have been sequential founder events associated with a stepping-stone colonization process (e.g. [15]–[18])

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