Meeting Abstract

P1.133  Jan. 4  Model-Averaged Phylogenetic Inference of the Triggerfishes (Family: Balistidae) DORNBURG, A*; ALFARO, M.E.; Washington State University

The triggerfishes (family Balistidae) comprise approximately 40 species in 11 genera and are among the most conspicuous and common diurnal inhabitants of coral reef communities worldwide. Despite their ecological and commercial importance, relatively little is known of their interspecific relationships. We present a novel phylogenetic hypothesis for the family Balistidae based on an analysis of two mitochondrial (12S, 16S) and three nuclear genes (4C4, Rhodopsin, RAG1) sampled from 24 ingroup species. As part of our analysis, we implemented a recently developed reversible jump MCMC so that our estimate of clade posterior probabilities reflects uncertainty in the choice of a substitution model. Our results strongly support the monophyly of the family but suggest that the genera Balistoides and Pseudobalistes are paraphyletic with respect to other balistids. We found Xanthichthys to be the sister group to a large clade including Rhinecanthus, Sufflamen, Balistes, and Canthidermis. We also found strong support for a sister group relationship between Rhinecanthus and Sufflamen + Abalistes. Comparison of model-averaged posterior probabilities with those from traditional MCMC reveals that failure to accommodate model uncertainty can lead to inflated confidence. Bayesian divergence time estimates under an uncorrelated rates model suggest that the MRCA of the crown Balistidae appeared at the start of the Miocene (~23 MYA). The timing and pattern of diversification events suggests that the triggerfish radiation may have been influenced by the mid-Miocene regionalization of marine invertebrate communities. Supported by NSF DEB-0445453 to MEA.