Life Sciences Commons^™

Quantifying Within-Population Variation In Mate Choice; Discrimination, Mate Sampling Rules, Multivariate Preference & Consequences For Sexual Selection, Kane David Stratman

Theses and Dissertations

Mate choice is foundational to the evolution of elaborate, conspicuous, and often energetically costly displays. Modelling sexual selection in any mating system is a complicated task on two fronts; we typically confront variation in both i) the strategies of signalers and ii) how choosers assess and sample among them. As selection on mate choice behaviors emerges from the relationship between these sources of variation, it is essential that they be measured in detail. Population-level measures of chooser behaviors (i.e. pooling the single responses of a sample of choosers) have long dominated the literature on mate choice, leaving open the possibility …

Diversity, Function, And Phenotypic Plasticity Of Cryptophyte Phycobiliproteins, Kristiaän Merritt

Theses and Dissertations

Cryptophytes are a group of unicellular eukaryotic algae that can be found in a wide range of underwater habitats. Part of their ecological success can be attributed to their diverse array of cryptophyte phycobiliproteins (Cr-PBPs), a pigment class that captures wavelengths of light that are poorly absorbed by chlorophylls. Cryptophytes gained photosynthesis via secondary endosymbiosis in which their ancestor engulfed a red algal endosymbiont. Following endosymbiosis, they deconstructed the red algal photosynthetic machinery to form the Cr-PBP. Since then, the Cr-PBPs have diversified into at least 9 spectrally distinct forms. I investigated the diversity of Cr-PBP light absorption across 76 …

Identifying Positive Selection In Multiple Subspecies Of Xylella Fastidiosa, Daniel Doroteo Flores

Theses and Dissertations

For this study, we will be looking to identify positive selection in eight genomes of the bacterial plant pathogen Xylella fastidiosa. A previous study used a branching method that identified 2 genes with positive selection along with a site-specific method identifying 34 genes showing positive selection. This current study focused specifically on the site-specific method, resulting in 28 genes (of 1,039 tested) showing positive selection. Of the 28 genes showing positive selection, 12 of them come from the pathogenicity, virulence and cellular structural categories. The remaining genes are found in the biosynthesis, metabolism, macro metabolism, and cellular process categories. …

Characterization And Analysis Of The Avian Epidermal Differentiation Complex And Implications In Feather Evolution, Anthony Chastine Davis

Theses and Dissertations

Since the most recent major mass-extinction event ~65 million years ago, birds have expanded to now occupy a wide range of habitats and exhibit diverse lifestyles. A major reason for this evolutionary success is the mechanical resilience and diversity of their epidermal appendages such as feathers, scales, and beaks. The diversity of these appendages, specifically feathers has played a critical role in their evolutionary success. The feathers of birds vary substantially across different species, as well as at different life stages and anatomical locations on an individual bird. Several of the genetic elements involved in the development and structure of …

Multispecies Character Displacement In Mexican Poeciliopsis Fishes, Andrea J. Roth

Theses and Dissertations

Competition has long been recognized as a central force in shaping evolution, particularly through character displacement. Yet research on character displacement is biased as it has focused almost exclusively on pairs of interacting species while ignoring multispecies interactions. Unfortunately, communities are seldom so simple that only pairs of species interact, and it is not clear if inferences from pairwise interactions are sufficient to explain patterns in nature. A more realistic approach is to ask how traits evolve when multiple species interact. Here I explore the importance of multispecies competitive interactions on trait evolution in four congeneric species of livebearing fishes …

The Evolutionary Significance Of Body Size In Burying Beetles, Ashlee Nichole Momcilovich

Theses and Dissertations

Body size is one of the most commonly studied traits of an organism, which is largely due to its direct correlation with fitness, life history strategy, and physiology of the organism. Patterns of body size distribution are also often studied. The distribution of body size within species is looked at for suggestions of differential mating strategies or niche variation among ontogenetic development. Patterns are also examined among species to determine the effects of competition, environmental factors, and phylogenetic inertia. Finally, the distribution of body size across the geographic range of a species or group of closely related is looked at …

Natural And Anthropogenic Drivers Of Tree Evolutionary Dynamics, Brandon M. Lind

Theses and Dissertations

Species of trees inhabit diverse and heterogeneous environments, and often play important ecological roles in such communities. As a result of their vast ecological breadth, trees have become adapted to various environmental pressures. In this dissertation I examine various environmental factors that drive evolutionary dynamics in threePinusspecies in California and Nevada, USA. In chapter two, I assess the role of management influence of thinning, fire, and their interaction on fine-scale gene flow within fire-suppressed populations of Pinus lambertiana, a historically dominant and ecologically important member of mixed-conifer forests of the Sierra Nevada, California. Here, I find evidence …

Phylogenetics, Biogeography, And Patterns Of Diversification Of Geckosacross The Sunda Shelf With An Emphasis On The Genuscnemaspis (Strauch, 1887), Perry Lee Wood

Theses and Dissertations

In my dissertation I investigate two genera of geckos (Cyrtodactylus and Cnemaspis) that are distributed across Southeast Asia with an emphasis on Cnemaspis. In Chapter 1 I use a multilocus dataset, ancestral area analyses, and molecular clock dating to generate a species level time calibrated phylogeny to test the monophyly of Cyrtodactylus and to identify major biogeographical patterns. I identified that Cyrtodactylus is monophyletic only if the the Sri Lankan genus often recognized as Geckoella is included. The results of the Biogeographical analyses reveal a west to east pattern of diversification. Chapter 2 I use a traditional morphological dataset to …

Phylogenetics, Biogeography, And Patterns Of Diversification Of Geckosacross The Sunda Shelf With An Emphasis On The Genuscnemaspis (Strauch, 1887), Perry Lee Wood

Theses and Dissertations

In my dissertation I investigate two genera of geckos (Cyrtodactylus and Cnemaspis) that are distributed across Southeast Asia with an emphasis on Cnemaspis. In Chapter 1 I use a multilocus dataset, ancestral area analyses, and molecular clock dating to generate a species level time calibrated phylogeny to test the monophyly of Cyrtodactylus and to identify major biogeographical patterns. I identified that Cyrtodactylus is monophyletic only if the the Sri Lankan genus often recognized as Geckoella is included. The results of the Biogeographical analyses reveal a west to east pattern of diversification. Chapter 2 I use a traditional morphological dataset to …

Virulence Of Photorhabdus Spp.: Examining The Roles Of Environment, Evolution, And Genetics In Insect Mortality, Dana Blackburn

Theses and Dissertations

Entomopathogenic nematodes (EPNs) (genera Heterorhabditis and Steinernema) kill their invertebrate hosts with the aid of a mutualistic bacterium. The bacteria (Xenorhabdus spp. for steinernematids and Photorhabdus spp. for heterorhabditids) are primarily responsible for killing the host and providing the nematodes with nutrition and defense against secondary invaders. Photorhabdus is a Gram-negative bacterium in the Enterobacteriaceae family with high virulence towards their insect hosts. To achieve high mortality rates Photorhabdus produces a variety of virulence factors such as toxins, lipases, proteases, secretion systems, and fimbriae. EPNs are amenable to laboratory rearing and mass production for biocontrol applications against insects …

Mysteries Of The Trypanosomatid Maxicircles: Characterization Of The Maxicircle Genomes And The Evolution Of Rna Editing In The Order Kinetoplastida, Preethi Ranganathan Iyengar

Theses and Dissertations

The trypanosomatid protists belonging to Order Kinetoplastida are some of the most successful parasites ever known to mankind. Their extreme physiological diversity and adaptability to different environmental conditions and host systems make them some of the most widespread parasites, causing deadly diseases in humans and other vertebrates.

This project focuses on their unique mitochondrion, called the kinetoplast, and more specifically involves the characterization of a part of their mitochondrial DNA (also called kinetoplast DNA or kDNA), the maxicircles, which are functional homologs of eukaryotic mitochondrial DNA in the kinetoplastid protists. We have sequenced and characterized the maxicircle genomes of 20 …

Understanding The Evolutionary History Of Biochemical Innovation, Madeline Opal St. Julien

Theses and Dissertations

The serine protease (SP) gene family is an ecologically important gene family because of observed involvement in innate immunity, digestive processes, and embryological development of arthropods. In the past decade, all genes of the serine protease family have been classified in a number of arthropods, with the exception of crustacean. Possible evolutionary mechanisms have been observed based off of varying selectional pressures acting on recent SP expansions in respect to varying diets. Daphnia is the first crustacean to have its genome sequenced, and their genomes were analyzed in this study to elucidate the expansion and divergence of the SP gene …

Differential Expression Of Snmps And Their Underlying Transcriptional Regulation In Chemosensory Pathways Of Drosophila, Richard A. Fandino

Theses and Dissertations

Insects possess complex and diverse chemosensory pathways which have specific phenotypes determined by the regulated expression of specific combinations of genes. While many of these genes (e.g. ORs and GRs) have very narrow expression patterns, associating with only a limited number of chemosensory sensilla, SNMPs show a very broad expression pattern. In Drosophila, SNMP1 and SNMP2 associate with the majority of olfactory and gustatory sensilla, but express in different cell types. In olfactory sensilla, SNMP1 and SNMP2 associate with trichoid or coeloconic neurons respectively, and both additionally express in a variety of sensilla support cells; in gustatory sensilla, SNMP2 expresses …

Impact Of Self-Fertilization On Fecundity, The Timing Of First Reproduction, And Population Genetic Structure: Is A Mate Worth The Wait?, Serena Caplins

Theses and Dissertations

Organisms capable of self-fertilization typically exhibit two evolutionary syndromes uniting high inbreeding depression with low levels of selfing, or low inbreeding depression and high levels of selfing. This study tests for inbreeding depression in an apparent self-compatible, hermaphroditic marine nemertean worm, Prosorhochmus americanus. Fecundity and timing to first reproduction were assessed in isolated and paired worms. Isolated worms produced significantly more offspring than paired worms and did not show inbreeding avoidance. The selfing rate of natural populations was evaluated using species-specific microsatellites and is consistent with preferential selfing (mean: 0.801), though some outcrossing appears to take place. Population genetic structure …

Genetic Variability, Pathogen Susceptibility, Subspecies Identity And Conservation Of The Endangered Northern Flying Squirrel (Glaucomys Sabrinus) In Virginia, James Lincoln Sparks Jr.

Theses and Dissertations

I examined the population genetic structure of three known subspecies of Glaucomys sabrinus from Appalachia, Washington State, and two previously unexamined populations from Mount Rogers National Recreation Area (MRNRA) in Southwestern Virginia. Mean FST (0.107) and an AMOVA (P G. sabrinus subspecies populations in the southern Appalachians are genetically differentiated. Glaucomys sabrinus at MRNRA were less inbred than expected. Gene flow, a consensus tree based on Nei's genetic distance, elevated heterozygosity and morphometric data suggest that the MRNRA G. sabrinus population is an intergrade of the two recognized Appalachian subspecies, G. s. fuscus and G. s. coloratus. I compared inbreeding …

Evolution And Phylogeny Of Basal Winged Insects With Emphasis On Mayflies (Ephemeroptera), Thomas H. Ogden

Theses and Dissertations

Ephemeroptera (mayflies) is a monophyletic group of semi-aquatic pterygote insects, comprising 3083 species, 376 genera, and 37 described families and are present on all continents, excluding Antarctica, being associated with freshwater and brackish water habitats. The order is unique among pterygote insects in possessing functional wings at the penultimate molt (subimago stage), prior to the full development of genitalia; in all other insects the presence of functional wings occurs only after the final molt. The purpose of this dissertation is to use molecular and morphological data, in order to investigate the position of the order Ephemeroptera among other insect orders, …

Prevalence Of Teleological And Lamarckian Misconceptions Of Natural Selection Among College Students, Bryce T. Battisti

Theses and Dissertations

Science teachers and researchers note that students must correctly understand the role of natural selection in evolution to make sense of biology. The level of understanding of natural selection can be assessed using the Conceptual Inventory of Natural Selection (CINS) which is a 20-item multiple-choice test that incorporates student misconceptions as distractors. In the present study, Item Response Theory (IRT) was used to analyze the occurance of misconceptions on the CINS among 1192 students in an introductory non-majors biology course. The four most difficult topics in the CINS are: (a) how change occurs in a population; (b) origin of variation; …