The Central Highlands fish fauna is a complex assemblage of hundreds of species, many
showing a high degree of endemicity. This diversity has traditionally been explained by
invoking relatively simple vicariance and dispersal scenarios. In my study, I assembled
all existing phylogenies of fishes from the Central Highlands to conduct a Phylogenetic
Analysis for the Comparison of Trees, which revealed that vicariance and dispersal
events have both played a role in the formation of the Central Highlands ichthyofaunas.
Evidence of co-ordinated dispersal and area reticulation was also discovered. The fauna
of some regions, in particular the Tennessee River basin, is shown to have accumulated
due to multiple vicariance and dispersal events.
One mitochondrial and seven nuclear loci were sequenced for the members of
the Etheostoma zonale species group. A high degree of geographical structure was
found, with twelve reciprocally monophyletic mitochondrial clades in E. zonale, and
nine in E. lynceum. Species tree analysis demonstrated the monophyly of both species.
One clade found in the Upper Tennessee River basin was found to have undergone
introgression with a second clade.
One mitochondrial and three nuclear loci were sequenced for the members of the
Luxilus zonatus species group. Four mitochondrial introgression events were found in the group, involving all three members of the L. zonatus group as well as two other
species of Luxilus. The geographical extent of the introgression events varies, as does
their time of occurrence.
A Hierarchical Approximate Bayesian Computation was performed on a set of
sister clades of three taxa found in the Ozark and Ouachita Mountains: two clades of
Etheostoma zonale, two clades of E. blennioides, and Luxilus cardinalis and L. pilsbryi.
All taxon pairs share the same geographical split; the analysis showed that two of these
divergences did not happen at the same time as the third, and are thus pseudocongruent.
The results of this study show that the Central Highlands ichthyofauna has a
more complex history than has been believed, and suggest methods of reconstructing
such complex histories which should prove useful in biogeographical studies of similarly
University of Minnesota Ph.D. dissertation. September 2011. Major: Ecology, Evolution and Behavior. Advisor: Andrew Simons. 1 computer file (PDF); vi, 168 pages.
Assessing the prevalence of common patterns and unique events in the formation of biotas: a study of fish taxa of the North American central highlands.
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