Ecology and Evolutionary Biology Commons^™

Impacts Of Bacterial Evolution On Host Lethality In Drosophila, Andrew Preston

College of Arts & Sciences Senior Honors Theses

Evolution is the process by which species change their genetic traits, such as the pathogenicity of bacteria, over time in response to changes in their environment. Although the genetic mechanisms underlying many evolutionary processes have been revealed, it is still not well understood how opportunistic pathogens, such as Pseudomonas aeruginosa, become virulent. The overall goal of this thesis is to test the Coincidental Evolution Hypothesis, which proposes that the virulence of opportunistic pathogens evolves coincidentally as a by-product of their interaction with their natural predators. I hypothesized that the virulence of ancestral Pseudomonas aeruginosa changes over time if it co-evolves …

Why The Delay In Recognizing Terrestrial Obligate Cave Species In The Tropics?, Francis G. Howarth

International Journal of Speleology

“Nothing could possibly live there!” They believed. Indeed, until recently, few specialized cave- adapted animals were known from volcanic, tropical, or oceanic island caves, and plausible theories had been put forward to explain their absence. But assume nothing in science! One must illuminate, explore, and survey habitats before declaring them barren. Our understanding of cave biology changed dramatically about 50 years ago following the serendipitous discovery of cave-adapted terrestrial arthropods in Brazil and on the young oceanic islands of the Galápagos and Hawai‘i. These discoveries and subsequent studies on the evolutionary ecology of cave animals have revealed a remarkable hidden …

The Effects Of Internal Physiology On Polyphenic Horn Development In The Dung Beetle Onthophagus Taurus, Naomi Garrett Williamson

Graduate Theses, Dissertations, and Problem Reports

An organism’s phenotype can be affected in development by alterations to gene expression based on environmental inputs. Nutrition is one such environmental input and the central regulator of development of large horn or small horn phenotypes in the dung beetle species, Onthophagus taurus. However, little is known about the nature of chemical compounds that are critical to this plastic horn development. To better understand these compounds, we are utilizing an untargeted metabolomic approach as well as a targeted gene approach. Through the metabolomic approach, it was uncovered that environmental conditions tend to have a greater impact on metabolomic composition …

Reproductive Character Displacement In Calopteryx Aequabilis And C. Maculata: Improving Species Recognition Through The Divergence Of Male Mating Preferences, Melissa Encinias

Masters Theses, 2010-2019

An ongoing evolutionary question is how co-occurring species maintain reproductive barriers when they are morphologically, behaviorally, and ecologically similar. Without geographic isolation, traits involved in species recognition may be under selection to enhance reproductive barriers. Exaggerated trait differences between species in sympatric populations may reflect selection to reduce misdirected mating between species, or reproductive character displacement. While this phenomenon is widely recognized as an important stage in the speciation process, there is little direct evidence of this process in nature. In two North American damselfly species, Calopteryx aequabilis and C. maculata, wing pigmentation is sexually dimorphic and also shows …

A Phylogenetic Analysis Of Bostrichoidea (Coleoptera) And Revisions Of The Southern African Spider Beetle Genera Meziomorphum And Eutaphroptinus (Ptinidae: Coleoptera), Olivia M. Gearner

Masters Theses & Specialist Projects

Proposals for the internal relationships and classification of the bostrichoids are currently poorly supported, and almost all are based on morphology alone. This study improves upon on previous phylogenetic analyses of the group by including more taxa using the standard genes for many phylogenetic analyses. Cytochrome C oxidase subunit 1 (CO1), 28S small subunit rRNA, and 16S small subunit rRNA mitochondrial genes were sequenced or obtained from Genbank, then analyzed using parsimony and Bayesian analyses. Topologies differed depending on genes used. A three gene tree and a two gene (28S and CO1) tree both supported relationships in which a basal …

Shaping The Tools Of Battle : Sexual Selection, Contest Dynamics, And Weapon Divergence In The Asian Rhinoceros Beetle Trypoxylus Dichotomus, Jillian F. Del Sol

Graduate Student Theses, Dissertations, & Professional Papers

Exaggerated weapons of sexual selection often diverge more rapidly and dramatically than other body parts, suggesting that relevant agents of selection may be discernible in contemporary populations. I examined the ecology, reproductive behavior, and strength of sexual selection on horn length in five recently diverged beetle populations that differ in relative horn size. I show that mating system ecology differs between these locations and corresponds with the local strength of contemporary selection on horn length. Comparisons of ecological conditions and selection strength across populations offer a critical first step towards meaningfully linking mating system dynamics, selection patterns, and diversity in …

Advancing Behavioural Genomics By Considering Timescale, Clare C. Rittschof, Kimberly A. Hughes

Entomology Faculty Publications

Animal behavioural traits often covary with gene expression, pointing towards a genomic constraint on organismal responses to environmental cues. This pattern highlights a gap in our understanding of the time course of environmentally responsive gene expression, and moreover, how these dynamics are regulated. Advances in behavioural genomics explore how gene expression dynamics are correlated with behavioural traits that range from stable to highly labile. We consider the idea that certain genomic regulatory mechanisms may predict the timescale of an environmental effect on behaviour. This temporally minded approach could inform both organismal and evolutionary questions ranging from the remediation of early …

Eight-Legged Encounters—Arachnids, Volunteers, And Art Help To Bridge The Gap Between Informal And Formal Science Learning, Eileen Hebets, Melissa Welch-Lazoritz, Pawl Tisdale, Patricia Wonch Hill

Eileen Hebets Publications

Increased integration and synergy between formal and informal learning environments is proposed to provide multiple benefits to science learners. In an effort to better bridge these two learning contexts, we developed an educational model that employs the charismatic nature of arachnids to engage the public of all ages in science learning; learning that aligns with the Next Generation Science Standards (NGSS Disciplinary Core Ideas associated with Biodiversity and Evolution). We created, implemented, and evaluated a family-focused, interactive science event—Eight-Legged Encounters (ELE)—which encompasses more than twenty modular activities. Volunteers facilitated participant involvement at each activity station and original …

The Genetic And Environmental Basis For Chc Biosynthesis In Drosophila, Heather Ke Ward

Electronic Thesis and Dissertation Repository

Cuticular hydrocarbons (CHCs) are produced by insects and primarily used to prevent desiccation. In Drosophila, certain compounds have secondary roles as infochemicals that may act during courtship to influence mate choice. Certain CHCs may stimulate courtship with heterospecifics or act to repel conspecifics. The CHC profile produced by an individual is the result of the interaction between its genetic background and the environment, though the genes that underlie species differences in CHC production and how the environment can modulate the abundance of individual compounds within a species is not well known. Here, candidate gene CG5946 was found to be …

Review Of The Sub-Saharan Africa Species Of Dignomus And Phylogenetic Analysis Of The Bostrichoids (Coleoptera: Bostrichoidea: Ptinidae), Amelia Lesbeth Smith

Masters Theses & Specialist Projects

Sub-Saharan Africa is home to nine described species of Dignomus Wollaston, 1862. Study and dissection of specimens has led me to the hypothesis that there are nine undocumented species in this region. Descriptions and images of the new species are presented and discussed, along with a compiled list of all described species from the Sub- Saharan region. The probable biology as geographic distributions for members of the genus are also given.

Additionally, a phylogenetic analysis of 95 species of bostrichoids using CO1 molecular data was done with a focus on the origins of Dignomus and Pseudomezium. parsimony and bayesian analyses …

Nocturnal Foraging Enhanced By Enlarged Secondary Eyes In A Net-Casting Spider, Jay A. Stafstrom, Eileen A. Hebets

Eileen Hebets Publications

Animals that possess extreme sensory structures are predicted to have a related extreme behavioral function. This study focuses on one such extreme sensory structure—the posterior median eyes of the net-casting spider Deinopis spinosa. Although past research has implicated the importance of vision in the nocturnal foraging habits of Deinopis, no direct link between vision in the enlarged eyes and nocturnal foraging has yet been made. To directly test the hypothesis that the enlarged posterior median eyes facilitate visually based nocturnal prey capture, we conducted repeated-measures, visual occlusion trials in both natural and laboratory settings. Our results indicate that D. …

Investigating Physiological Collaborations Between A Lower Termite And Its Symbionts, Brittany F. Peterson

Open Access Dissertations

This project was completed in an effort to better understand the contributions of symbiotic microbes to the biology of Reticulitermes flavipes, the eastern subterranean termite. Lower-termites, like R. flavipes, house symbionts from all three domains of life within their hindgut paunch. This intimate association is reflected in nearly every aspect of termite biology. Here, I investigate these physiological collaborations as they relate to digestion and immunity. My efforts focused on 1) quantifying the role of bacteria in wood digestion within the termite gut, 2) evaluating the role of symbionts in protection against pathogens, and 3) identifying gene products that bacterial …

Benefits Of Size Dimorphism And Copulatory Silk Wrapping In The Sexually Cannibalistic Nursery Web Spider, Pisaurina Mira, Alissa G. Anderson, Eileen Hebets

Eileen Hebets Publications

In sexually cannibalistic animals, male fitness is influenced not only by successful mate acquisition and egg fertilization, but also by avoiding being eaten. In the cannibalistic nursery web spider, Pisaurina mira, the legs of mature males are longer in relation to their body size than those of females, and males use these legs to aid in wrapping a female’s legs with silk prior to and during copulation. We hypothesized that elongated male legs and silk wrapping provide benefits to males, in part through a reduced likelihood of sexual cannibalism. To test this, we paired females of random size with …

Biogeographical Patterns In The Hard-Tick Genus Amblyomma Koch 1844 (Acari: Ixodidae), Matthew H. Seabolt

Electronic Theses and Dissertations

Amblyomma Koch is a genus of hard-ticks with approximately 130 species. Its geographical range is typical for organisms with a Gondwanan origin. A majority of these species are endemic to the Neo- and Afrotropical regions, with the remaining taxa dispersed throughout Southeast Asia, Australia and the Pacific islands. Based on this distribution, we hypothesize that the genus dispersal patterns will mirror the fragmentation and continental drift of the Gondwanan supercontinent. Maximum parsimony, maximum likelihood, Bayesian inference and node-dating analyses of nuclear 18S rDNA gene sequences reveal a more recent origin and radiation patterns within the genus and suggest that Amblyomma …

Population And Demographic Structure Of Ixodes Scapularis Say In The Eastern United States., Joyce M. Sakamoto, Jerome Goddard, Jason L. Rasgon

College of Agriculture & Life Sciences Publications and Scholarship

INTRODUCTION: The most significant vector of tick-borne pathogens in the United States is Ixodes scapularis Say (the blacklegged tick). Previous studies have identified significant genetic, behavioral and morphological differences between northern vs. southern populations of this tick. Because tick-borne pathogens are dependent on their vectors for transmission, a baseline understanding of the vector population structure is crucial to determining the risks and epidemiology of pathogen transmission. METHODS: We investigated population genetic variation of I. scapularis populations in the eastern United States using a multilocus approach. We sequenced and analyzed the mitochondrial COI and 16S genes and three nuclear genes (serpin2, …

Regional Comparison Of Overwintering Mortality, Fecundity, And Virulence In The Hemlock Woolly Adelgid, Artemis Demas Roehrig

Masters Theses 1911 - February 2014

Throughout the eastern United States, the spread of the hemlock woolly adelgid, Adelges tsugae Annand, has caused high mortality of eastern hemlocks Tsuga canadensis (L.). We recorded overwintering survival and fecundity of A. tsugae, and tree new growth at sites in the northeastern and southeastern United States and in a common garden experiment in Massachusetts.

Overwintering mortality of A. tsugae was much higher in the north (87%) than the south (37%) in 2009, and showed significantly positive density-dependence in the north only. In 2010, overwintering mortality decreased in both regions but remained higher in the north (54%) than the …

A Phylogenetic Analysis Of Armored Scale Insects, Based Upon Nuclear, Mitochondrial, And Endosymbiont Gene Sequences, Jeremy C. Andersen

Masters Theses 1911 - February 2014

Armored scale insects (Hemiptera: Diaspididae) are among the most invasive insects in the world. They have unusual genetic systems, including diverse types of paternal genome elimination (PGE) and parthenogenesis. Intimate relationships with their host plants and bacterial endosymbionts make them potentially important subjects for the study of co- evolution. Also, in some groups, the adult female never sheds the second instars cuticle, and remains within its confines, a habit referred to as the pupillarial habit. Here we expand upon recent phylogenetic work (Morse and Normark 2006) by analyzing a partitioned dataset including armored scale and endoysmbiont DNA from one hundred …