Award Date

1-1-2003

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Science

First Committee Member

Brett R. Riddle

Number of Pages

67

Abstract

The family Heteromyidae includes six genera of rodents traditionally placed in three subfamilies endemic to the Nearctic and northern Neotropical biogeographic regions. Although several of these taxa represent intensively studied members of North and Central American ecosystems (e.g., kangaroo rats, pocket mice), phylogenetic relationships within and among subfamilies, genera, and species-groups are poorly understood. Here, I used maximum likelihood (ML), Bayesian, and maximum parsimony (MP) analyses of sequence data from two mitochondrial DNA genes---COIII (699 bp) and cytochrome b (1140 bp)---to investigate phylogenetic relationships among 55 species-level taxa. I found robust support for monophyly of genera Dipodomys, Microdipodops, Chaetodipus, and Perognathus ; sampling of Liomys and Heteromys was inadequate to evaluate their reciprocal status. All analyses converge on a phylogeny that robustly resolves several historically contentious issues, including monophyly of the subfamily Dipodomyinae (Microdipodops + Dipodomys), and a monophyletic Chaetodipus that includes C. formosus, C. baileyi, C. rudinoris and C. hispidus. However, Perognathinae (Perognathus + Chaetodipus) is not supported, with no basal resolution among Perognathus, Chaetodipus, Dipodomyinae, and Heteromyinae. Many intrageneric clades receive strong support and are discussed herein; I used the phylogenetic information to evaluate several hypotheses regarding the evolution of the Heteromyidae. I separately evaluated the evolution of morphological characters (body size, number of hind toes [Dipodomys only], and rump spines [Chaetodipus only]) and macroecological evolution by coding each taxon into classes (body size---very small, small, medium, large, or very large; number of toes---4 or 5; rump spines---presence or absence) and biome-level categories (grassland steppe, chaparral, subtropical thornscrub, warm desert, or cold desert) and then tracing the history of the morphological characters and ecological transitions during radiation of extant groups using the Fitch optimization in MacClade. Because the mitochondrial DNA genes chosen for these analyses resulted in very limited resolution at the basal nodes of the Heteromyidae tree, recommendations for future directions of study are discussed.

Keywords

American; Biogeographic; Character Evolution; Dipodomyinae; Evolutionary; Family; Heteromyidae; Histories; North; Perognathinae; Rodent

Controlled Subject

Molecular biology; Zoology; Genetics

File Format

pdf

File Size

1925.12 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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