DISSERTATION RESEARCH: Phylogeny, biogeography, and convergent evolution in a radiation of Southeast Asian Rock Geckos (Cnemaspis Strauch, 1887).

Brigham Young University, Provo UT

Investigators

Abstract

Southeast Asia is one of the most intriguing and understudied biodiversity hotspots in the world. A prominent geological feature of this area is the Sunda Shelf, which is currently submerged beneath the South China Sea and underlies the Malay Archipelago. This region has a complex geological and climatic history, and serves as an excellent system to study drivers of biotic diversification. One group that occurs throughout this region is the rock gecko genus Cnemaspis. Theses geckos live on various substrates including different types of vegetation and rocks, including limestone, which is heavily mined in Southeast Asia for the production of cement. Mining and clearance of rainforest comprise serious threats to the unique biodiversity of this region. Studies of the endemic organisms of this region can contribute to conservation planning through the discovery of cryptic species and identification of local areas of high species diversity. This kind of knowledge is crucial to the implementation of effective science-based conservation strategies. This study will also further our understanding of the processes of speciation and adaptation to unique local environments, and the long-term accumulation of biodiversity which make this part of Asia so rich in endemic species. Portions of this research will be used to train undergraduates, and to develop a public display about biodiversity and species discovery at the Bean Life Science Museum at Brigham Young University. The genus Cnemaspis is widespread throughout Southeast Asia and is one of the most species-rich gecko genera in the region, with 54 described species. These presumed low vagility geckos live on a variety of substrates and vary in ecomorphology; and the clade is characterized by a number of micro-endemics, making it a great system for evolutionary study. In this project we will: (1) generate a well-supported multilocus time-calibrated phylogeny of the genus and test spatial and temporal divergence across the Sunda Shelf; (2) evaluate whether the polytomy in the preliminary phylogeny for the genus is 'hard' or 'soft', and if the former, whether it is an adaptive or non-adaptive radiation; and (3) investigate the effects on Cnemaspis species diversification (e.g. speciation and extinction rates) derived from the convergent evolution of ecomorphological characters. Currently one mitochondrial gene and three nuclear gene sequences resolve well-supported clades towards the tips of the tree, but fail to resolve deeper nodes. To test the hard vs. soft polytomy hypotheses, a 'Next Generation' sequence-capture method will be used to generate hundreds of loci. From this dataset a phylogenetic tree will be constructed to explicitly test alternative biogeographic hypotheses for colonization of parts of Sundaland, as well as test morphological disparity through time (DTT), convergent adaptive regime shifts, and evolution of ecomorphological characters.