Collaborative Research: Total Evidence Phylogeny of Gobioidei (Teleostei: Perciformes) and Cladistic Biogeography

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ABSTRACTTOTAL EVIDENCE PHYLOGENY OF GOBIOIDEI (TELEOSTEI: PERCIFORMES) AND CLADISTIC BIOGEOGRAPHY The fish suborder Gobioidei includes more than 2000 extant species of small fishes found throughout the tropical, subtropical, and temperate regions of the world, in freshwater and nearshore marine habitats. Many gobioids live on or near the bottom, often in burrows. Many others are reef-dwellers, a few are oceanic, and some estuarine representatives have the ability to breathe air. Their wide distribution and great diversity of form and ecology make gobioids ideal for studies of broad questions in vertebrate evolution and biogeography. However, the incredible gobioid diversity has also hindered investigations of their evolutionary relationships, and no comprehensive phylogenetic hypothesis for gobioids has been advanced. Previous studies have focused on small groups of taxa or restricted suites of characters, and because of the fishes' small size, the morphological characters identified are often reductive and highly variable. The closest relatives of Gobioidei are unknown, and the classification has been in flux. Currently, the roughly 270 gobioid genera are classified in nine families, some containing only a single genus. The larger families (Eleotrididae, Gobiidae) are almost certainly not natural groups, and the relationships of species within those families, and among families, are unknown.This study seeks to resolve gobioid relationships using a total evidence approach and focusing primarily on basal gobioid groups and outgroups. DNA sequence data from five genes (four mitochondrial and one nuclear) will be combined with osteological and myological characters. The data will be analyzed separately and combined, and the resultant phylogeny will then be used to produce a classification for the suborder. The phylogeny will be used to examine the historical biogeography of gobioids, using cladistic biogeographical techniques to discover congruent patterns of area relationships and examine the origins of gobioid diversification. The common assumption that gobioids originated in a marine environment and diversified into freshwater once or repeatedly will be investigated by mapping the distribution of habitats on the taxon cladogram.Gobioid fishes have been studied for over a century but the group is so large, diverse, and widely distributed that a comprehensive phylogenetic and biogeographic study has never been attempted. This study will provide the first such comprehensive phylogenetic hypothesis and provide the basis for exploring the biogeography of a major group of fishes. It will also provide a historical foundation for future studies that will examine ecology, adaptation, and development, using the potential of this diverse group as a model for research on many aspects of evolutionary biology.