Meeting Abstract

S1-2.3  Thursday, Jan. 3  Moving towards many-marker datasets: progress and challenges for turtle phylogenetics THOMSON, R.C.*; SHAFFER, H.B.; Univ. of California, Davis; Univ. of California, Davis rcthomson@ucdavis.edu

The field of systematics has seen rapid progress in applying molecular tools to the study of phylogeny, both at the species level and at deeper nodes in the tree of life. However, this progress has been limited, particularly in clades containing rapid and/or recent radiations, by an insufficient number of appropriate markers to resolve a well-supported topology. We used a simulation approach to examine how many nuclear sequence markers are needed to resolve a phylogenetic tree with high support given incongruity among gene trees, as is often expected for rapid radiations. We then designed a low-cost approach for developing large numbers of markers for non-model organisms where a single genomic resource was available. We designed oligonucleotide pairs to prime 96 nuclear loci in the western painted turtle (Chrysemys picta belli), using an existing end-sequenced bacterial artificial chromosome (BAC) library. These markers were tested in PCR assays across the turtle tree of life to evaluate amplification success across increasing phylogenetic distances. A subset of markers was then sequenced to examine their phylogenetic utility and to resolve a backbone for the turtle tree of life. Our simulation results suggest that it may not always be possible to resolve all nodes in a tree using traditional phylogenetic methods, although an increase in the amount of data can help and many nodes can be resolved with a high degree of support. We also found that existing genomic resources are a rich resource for developing broadly useful phylogenetic markers, even if that resource is only available for a single species.