Doctor of Philosophy (PhD)
The diversity of fishes in the Neotropics consists of nearly 6,000 species, approximately 10% of all vertebrate species on the planet. Evolutionary patterns and processes in fishes are often quite distinct from terrestrial biota, and the study of freshwater fishes can offer insight into understanding evolution and biogeography of regions. One of the major lineages of neotropical freshwater fishes, family Cichlidae, consist of over 500 species in the Neotropics but over 1,600 species overall. The aim of this study is to (1) assess diversification patterns within the family, with a focus on neotropical clades, (2) reassess phylogenetic relationships among northern Middle American cichlids and formally revise the taxonomy of this enigmatic group of fishes, and (3) assess phylogeographic structure within widespread Middle American fishes and begin exploring intrinsic capabilities that may influence our understanding of their biogeographic history. Results show that neotropical cichlids are relatively old in age and their diversity can be attributed to the age of the clade as opposed to an increase or decrease in rate of evolutionary diversification. For the northern Middle American herichthyin cichlids, a revised taxonomy of the group is offered based on robust taxonomic sampling and assessment of morphological characters to define genera. At a more exclusive taxonomic scale, phylogeographic structure is not observed for some lowland neotropical fishes in Middle America. Incorporation of physiological and behavioral data casts doubt on marine dispersal as the sole or primary mechanism of dispersal for these fishes. Overall results show the importance of an integrative approach to undertand the evolution and biogeography of freshwater fishes in the Neotropics.
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McMahan, Caleb D., "Diversification and Biogeography of Neotropical Cichlids" (2015). LSU Doctoral Dissertations. 3140.