Taking measurements of Seychelles caecilians.
Island archipelagos provide good opportunities to investigate evolutionary patterns and processes. The Seychelles archipelago , due to its partly Gondwanan history, harbours recent and ancient endemic amphibians, allowing for factors relating to island occupancy on evolution to be answered.
We investigated genetic variation in (1) a relatively recent endemic, the Seychelles tree frog Tachycnemisseychellensis(Hyperoliidae) thought to have arrived in the Seychelles via transoceanic dispersal 11 – 21 million years ago, and (2) a small ancient endemic caecilian radiation that has been on the Seychelles for at least 65 million years. We generated DNA sequence data for these taxa using multiple mitochondrial and nuclear markers. We found surprisingly low genetic variation in most of the caecilians and the tree frog, even among the different islands, and high variation in two of the caecilians.
Comparison of different amphibians and reptiles suggests that diversity within and among Seychelles islands is likely to be influenced by dispersal ability, response to environmental change, and duration of occupancy. We are in the process of gathering morphological data to corroborate these results.