Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis


Arts and Sciences



First Advisor

Dr. David. W. Weisrock


The analysis of diverse data sets can yield different phylogenetic estimates that challenge systematists to explain the source of discordance. The Ambystomatidae are a classic example of this phylogenetic conflict. Previous attempts to resolve the ambystomatid species tree using allozymic, morphological, and mitochondrial sequence data have yielded different estimates, making it unclear which data source best approximates ambystomatid phylogeny. We present the first multi-locus DNA sequencebased phylogenetic study of the Ambystomatidae. Because independent loci can contain discordant gene tree histories, concatenating unlinked loci into a single data matrix can lead to strongly supported and erroneous results. Therefore, we utilized a range of analyses, including coalescent-based methods of phylogenetic estimation that account for incomplete lineage sorting and concordance-based methods that estimate the proportion of sampled loci that support a particular clade. We repeated these analyses with the removal of individual loci to determine if any locus has a disproportionate effect on our phylogenetic results. Many deep and relatively shallow clades within Ambystoma were robustly resolved. Analyses that excluded loci produced overlapping posterior distributions, suggesting no disproportionate influence of any particular locus. Our estimates differ from previous hypotheses, although there was greater similarity with previous molecular estimates, relative to morphological estimates.

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