Speciation history and species-delimitation within the Seychelles Bronze geckos, Ailuronyx spp.: molecular and morphological evidence

摘要

Research on the genetic variability across various organisms from the Seychelles granitic islands has revealed considerable differentiation within many taxa, often with deep evolutionary lineages, likely corresponding to cryptic species. Although an accurate description of insular diversity is important for biogeographical and conservation reasons, there is frequently a lack of information even for presumably better known groups, such as vertebrates. One example is the endemic genus Ailuronyx, which includes the emblematic Seychelles giant bronze gecko Ailuronyx trachygaster. In the present study, we investigate, for the first time, based on morphological and molecular information, the intraspecific diversity of the three currently recognized Ailuronyx species, and reassess their distribution and history of diversification. Our data clearly indicate an old (Miocenic) divergence between these species, as well as the existence of cryptic diversity within Ailuronyx seychellensis, and, to a lesser extent, within Ailuronyx tachyscopaeus, that should be further explored and described. Preliminary data suggest concordant patterns of morphological and molecular differentiation. The results also show that, although morphological discrimination between the currently described species is possible, some previous distribution records based on observations may be wrong, which is important for conservation management. The observed genetic structure patterns are congruent with those of other endemic taxa from the Seychelles, again highlighting the evolutionary importance of historical fragmentation across this ancient archipelago, the existence of overlooked diversity, and the need for detailed morphological and genetic assessments to accurately identify and address conservation priorities. (C) 2016 The Linnean Society of London.