Abstract

Among the relatively depauperate herpetofauna of the Pacific, two families of lizards, the Scincidae and the Gekkonidae, are particularly speciose. The focus of this study is on the family Gekkonidae and the native species Gehyra oceanica and the introduced species Hemidactylus frenatus. Much of Hemidactylus frenatus and Gehyra oceanica’s distribution, abundance, and morphology in the Pacific Islands, and specifically in the Tongan archipelago, is undocumented. Both Gehyra oceanica and Hemidactylus frenatus occupy similar habitats, creating a competitive dynamic between native and non-native species. This study investigated differences in abundance, distribution, size structure on the islands of Tongatapu and ‘Atata for Hemidactylus frenatus and Gehyra oceanica. The frequency of occurrence of both species was found to be significantly dependent on sample location. No significant difference in abundance between ‘Atata and Tongatapu were found for Hemidactylus frenatus. Hemidactylus frenatus individuals sampled from ‘Atata were significantly larger than those sampled from Tongatapu. These results, while preliminary, suggest that ecological dynamics likely exist on and among these islands, with competitive interaction possible driving idiosyncratic population differences.

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