Model-Averaged Phylogenetic Inference of the Triggerfishes (Family: Balistidae)

Alex Dornburg

The triggerfishes (Family Balistidae) comprise approximately 40 species in 11 genera and are among the most conspicuous diurnal inhabitants of coral reef communities worldwide. Despite their ecological and commercial importance, relatively little is know of their interspecific relationships. Here we present a novel molecular phylogenetic hypothesis for the Family Balistidae based on an analysis of two mitochondrial (12S, 16S) and three nuclear genes (4C4, Rhodopsin, RAG1) sampled from 26 species. As part of our analysis, we implemented a recently developed reversible jump MCMC sampler that attempts to account for uncertainty in the underlying model of molecular substitution in Bayesian analysis. Clade posterior probabilities as well as parameter estimates thus reflect uncertainty in the choice of a substitution model. Comparison of model-averaged posterior probabilities with those from traditional MCMC reveals that model averaging had a negligible effect on clade posterior probabilities. The use of model averaging approaches in phylogenetics is an area of growing interest and this is the first study to test its effects on clade support values. Our phylogenetic results strongly support the monophyly of the family but suggest that the genera Balistoides and Pseudobalistes are paraphyletic with respect to other balistids. We also found strong support for Sufflamen as a sister group to the remaining Balistidae. We found Abalistes to be the sister group to a large clade including Melichthys, Xanthichthys, Balistes, and Canthidermis. Bayesian divergence time estimates under an uncorrelated rates model suggest that the MRCA of the crown group Balistidae appeared during the Late Oligocene (~25 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.

Model-Averaged Phylogenetic Inference of the Triggerfishes (Family: Balistidae)

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