Genetics and Genomics Commons^™

Population Structure Of The Lizard Ecpleopus Gaudichaudii Coincides With A Biogeographic Barrier - The Doce River, Alexander J. Garretson

Dissertations and Theses

Intraspecific genetic variation is an integral component of diversification and the accumulation of biodiversity. The degree to which isolated populations of the same species are genetically structured in geographical space is impacted by a variety of mechanisms. In this study, I document patterns and discuss possible drivers of genetic structure within Ecpleopus gaudichaudii, a lizard species endemic to the Atlantic Forest of Brazil. For that, I assembled ddRadseq sequences from 48 individuals across much of the range of the E. gaudichaudii and analyzed its population structure. I created an intraspecific phylogeny for this group utilizing RAxML and conducted a …

Mitonuclear Mismatch Is Associated With Increased Male Frequency, Outcrossing, And Male Sperm Size In Experimentally-Evolved C. Elegans, Brent William Bever

Dissertations and Theses

We provide the first controlled study of how male frequencies and rates of outcrossing evolve in response to mitonuclear mismatch by allowing replicate lineages of C. elegans nematodes containing either mitochondrial or nuclear mutations of electron transport chain (ETC) genes to evolve under three sexual systems: facultatively outcrossing (wildtype), obligately selfing, and obligately outcrossing. In partial support of a tenet of the mitonuclear sex hypothesis, which predicts that outcrossing will be favored in cases of mitonuclear mismatch, we found evolution of increased male frequency in at least one replicate line of all four ETC mutant backgrounds tested--nuclear isp-1, mitochondrial …

Multi-Locus Phylogenetic Inference Of The Howler Monkey (Alouatta) Radiation In South America., Esmeralda Ferreira

Dissertations and Theses

Abstract

Howler monkeys (Alouatta) are the most widely distributed New World primates, ranging from southern Mexico to northern Argentina. They occur in tropical rain forests, flooded and gallery forests, and deciduous and semi-deciduous environments. Despite their importance as seed dispersers, howlers have also been known to be ecological indicators. Available phylogenetic hypotheses for this genus have used chromosomal characters, morphological characteristics, and a limited number of molecular markers and specimens. In spite of these analyses, branching patterns among howler species lineages conflict between studies or remain unresolved. Using 14 unlinked non-coding intergenic nuclear regions under both a concatenated …

Accumulation And Transmission Dynamics Of A Naturally-Occurring Mtdna Deletion In Caenorhabditis Briggsae, Jennifer Anne Sullins

Dissertations and Theses

Maintaining mitochondrial genome sequence integrity is essential for preserving normal mitochondrial function. Several human diseases have been associated with heteroplasmic mitochondrial genome mutations, but few genetic systems can simultaneously represent pathogenic mitochondrial genome evolution and inheritance. The nematode Caenorhabditis briggsae is one such model. Natural C. briggsae isolates are globally-distributed and phylogenetically grouped into three distinct clades, with isolates exhibiting varying levels of a large-scale mtDNA deletion, nad5∆. Furthermore, a small subset of clade II isolates exhibits putative compensatory mutations that may reduce the risk of deletion formation and accumulation in those populations. In this thesis, the author characterizes the …

A Phylogenetic And Environmental Analysis Of Brazilian Placosoma Lizards, Kai A. Farje-Van Vlack

Dissertations and Theses

Placosoma is a genus comprised of the Brazilian spectacled lizards P. champsonotus, P. cipoense, P. cordylinum, P. glabellum, and P. limaverdorum. While P. champsonotus, P. cordylinum, and P. glabellum occupy the southern coast of Brazil, P. cipoense is found in the montane grasslands north of that range, and P. limaverdorum was recently discovered in forest isolates that persist within the semi-arid Caatinga. This study elucidates the ecological and evolutionary relationships among these morphologically similar lizards. Using mitochondrial and nuclear gene sequences, genus-wide phylogenies were inferred through Bayesian inference and a species tree approach, …

Mechanisms Of Adaptation In The Newly Invasive Species Brachypodium Sylvaticum (Hudson) Beauv., Gina Lola Marchini

Dissertations and Theses

It is common knowledge that invasive species cause worldwide ecological and economic damage, and are nearly impossible to eradicate. However, upon introduction to a novel environment, alien species should be the underdogs: They are present in small numbers, possess low genetic diversity, and have not adapted to the climate and competitors present in the new habitat. So, how are alien species able to invade an environment occupied by native species that have already adapted to the local environment? To discover some answers to this apparent paradox I conducted four ecological genetic studies that utilized the invasive species Brachypodium sylvaticum (Hudson) …