Phylogenetic Systematics of Coral Reef Fishes

A major challenge in biology is the resolution of phylogenetic relationships among diverse clades of fishes inhabiting coral reefs around the world.  Collections are obtained through an active field program of visiting coral reefs in the Philippines, Papua New Guinea, Australia, and Pacific Islands, as well as the Caribbean, collecting fishes using SCUBA diving, nets and working with fishermen.  Phylogenetic systematics is the generation of molecular and morphological data from those collections, followed by large-scale data analysis to yield phylogenetic trees, which represent our best estimate of the family tree of relationships among fish species. Generating phylogenetic trees is one of the most useful and exciting areas in biology today.

Objectives: We are exploring the phylogenetic relationships of several major lineages of coral reef fishes in order to understand the causes and consequences of high biodiversity, molecular evolution, and the evolution of structure and function in these diverse groups. We use the phylogenies generated from both morphology and molecules to look at the evolution of characters such as biomechanics of the jaws for feeding, and functional morphology of locomotor structures.

Labridae. The largest group we are studying are the bright and colorful wrasses of the family Labridae. Wrasses are a diverse group of over 600 fish species in 66 genera that vary in body shape, size, coloration, and habitat (Westneat 1997). In addition to a large data set generated using comparative morphology, we are using mitochondrial regions (12s, 16s, CytB) and several nuclear genes (Bmp4, Otx1, Dlx2, Tmo4C4 and RAG2) to assess phylogenetic relationships among the lineages of labrids, including most genera and nearly 300 species (plus multiple outgroups). Preliminary results with these genetic data show good resolving power among higher taxa in the family. Phylogenetic patterns generated from this data will provide an evolutionary framework for research on the biology of labroids ranging from rates of genetic change to the evolution of feeding mechanisms and breeding behavior.

Scaridae. The parrotfishes are lovely beaked fishes that browse on algae and coral on reefs throughout the world. We now know that they are in fact wrasses! They fall out as a sub-group of the Labridae, and the 88 species of scarids have received considerable attention due to their significant ecological role in algal herbivory and sand production during digestion. We continue to look at parrotfish phylogenetics and evolution, including studies of their feeding mechanisms, the evolution of regulatory genes in this diverse group, and their contribution to coral reef ecology.

Chaetodontidae and Pomacanthidae. The butterflyfishes and marine angelfishes are some of the most beautiful animals found on Earth. Building on recent work, we are continuing to collect data on the relationships among the these two related families with tissue samples collected from the world’s oceans, including Caribbean, Pacific, Indian Ocean, and Red Sea species. Molecular phylogenies will provide an assessment of evolutionary patterns in these colorful animals, and enable us to examine the evolution of color patterns and pair-bonding during breeding.

Some Lab References on Reef Fish Phylogenetics

Cooper, W. J., and M. W. Westneat.  (2009). Form and function of damselfish skulls: rapid and repeated evolution into a limited number of trophic niches. BMC Evolutionary Biology 9:24.

Cooper, W. J., Smith, L. L. and M. W. Westneat.  (2009). Exploring the radiation of a diverse reef fish family: Phylogenetics of the damselfishes (Pomacentridae), with new classifications based on molecular analyses of all genera. Molecular Phylogenetics and Evolution52: 1-16.

Smith, L. L.,Fessler, J. L., Alfaro, M. E., Streelman, J. T. and M. W. Westneat.  (2008). Phylogenetic relationships and evolution of regulatory gene sequences in the parrotfishes. Molecular Phylogenetics and Evolution 49: 136-152.

López, J. A.,  M. W. Westneat, and R. Hanel.  2007. The phylogenetic affinities of the mysterious anguilliform genera Coloconger and Thalassenchelys as supported by mtDNA sequences. Copeia 959-966.

Fessler, J. L. and M. W. Westneat. 2007. Molecular phylogenetics of the butterflyfishes (Chaetodontidae): Taxonomy and biogeography of a global coral reef fish family. Molecular Phylogenetics and Evolution 45, 50-68.

Westneat, M. W. and M. E. Alfaro.  2005. Phylogenetic relationships and evolutionary history of the reef-fish family Labridae. Molec. Phylog. Evol. 36: 370-390.

Westneat, M. W., M. E. Alfaro, P. C. Wainwright,  D. R. Bellwood, J. R. Grubich, J. Fessler, K. D. Clements, and L. Smith.  2005. Local phylogenetic divergence and global evolutionary convergence of skull biomechanics in reef fishes of the family Labridae. Proc. Roy. Soc. B. 272: 993-1000.

Westneat, M. W. 1997. Family Labridae. The Western Central Pacific: FAO species identification sheets for fishery purposes. Food and Agriculture Organization of the United Nations.

Westneat, M.W. 1995a. Feeding, function, and phylogeny: Analysis of historical biomechanics and ecology in labrid fishes using comparative methods. Systematic Biology 44: 361-383.

Westneat, M.W. 1995b. Systematics and biomechanics in ecomorphology. Env. Biol. Fish 44:263-83.