Origins of softshell turtles in Hawaii with implications for conservation

摘要

Non-native species have the potential to induce large-scale ecological changes that threaten native ecosystem biodiversity, particularly on islands. However, aside from the most conspicuous invasive taxa, the majority of non-natives receive relatively little scientific attention making it difficult to predict the severity of their impact. In addition to ecological and natural history data, genetic approaches can help address the status of non-natives, particularly for introductions that involve multiple sympatric and morphologically cryptic species to clarify their taxonomic identities and geographic origins. We used a molecular systematic approach to investigate softshell turtles (family: Trionychidae) introduced to the Hawaiian Islands in the late 1800s: Palea steindachneri and Pelodiscus sinensis. In light of extended importation and inter-island dispersal, recent taxonomic revisions in P. sinensis, unknown ecosystem impacts in Hawaii, and native range conservation concerns, a comprehensive characterization of the populations in Hawaii was warranted. Field surveying efforts revealed a distribution markedly different from the historical one, with the current ranges of P. steindachneri limited to Kauai and that of Pelodiscus limited to Oahu. Analysis of the 12S rRNA, ND4, and Cyt b gene regions revealed two species of the Pelodiscus complex (P. sinensis sensu stricto and P. maackii) and low genetic diversity in P. steindachneri. These results suggest the importance of continued study to assess impacts on Hawaiian species with the aim of developing management policies to either protect them as 'assurance colonies' for the declining native populations or alternatively to support the control and eradication efforts aimed at these introduced aquatic predators.