Evolution Commons^™

The Island Biogeography Of Mangrove-Dwelling Vertebrates: Isolation, Specialisation, And Extinction, Jian Xiong David Tan

Biology ETDs

Mangroves are highly dynamic ecosystems that are widely distributed across the coastlines of the tropics and subtropics. Despite their low plant diversity, mangroves host a disproportionately high number of terrestrial vertebrate taxa. However, mangrove specialists — taxa that only occur in mangrove habitats — exhibit a global distribution that is incongruous with the broader background distribution patterns of mangrove-associated fauna, exhibiting higher diversity in Australia and Southeast Asia. This dissertation therefore aims to assess how the diversity and distribution of mangrove specialist fauna may have been shaped by the historical biogeography of mangroves, and the effects of mangrove specialisation on …

The Role Of Elevation In The Migration, Physiology, And Genomic Diversification Of Birds, Jessie L. Williamson

Biology ETDs

Elevational gradients cause profound eco-climatic variation across short distances. Partial pressure of oxygen (PO₂) is a severe challenge that organisms face at high elevations; due partly to specialization on PO₂, most Neotropical bird species have narrow elevational ranges. However, a small fraction are elevational generalists that span sea level to high elevations, and a subset undertake extreme migratory journeys from low to high elevations biannually. My dissertation combines diverse approaches across levels of biological organization to understand how elevation impacts the ecology, evolution, physiology, and migration of montane birds. I examined ‘extreme’ elevational …

Connecting Climate And Geography With Diversification And Conservation Of A Western North American Endemic Mammal, Sorex Monticola, Antonia Androski

Biology ETDs

Repeated glacial cycles of the Pleistocene initiated complex sequences of divergence and secondary contact with gene flow for many North American species. In my first chapter, I expand our understanding of the phylogeography of the montane shrew, Sorex monticola, with range-wide genetic sampling and geospatial analyses to reconstruct the history of clades within this species and test whether evolutionarily divergent clades occupy distinct abiotic niches. In my second chapter, I build upon these hypotheses, providing the first estimates of evolutionary relationships and timing of diversification based on genome-wide markers. In my third chapter, I use a systematic review of the …

Unraveling The Paradox Of The 'Great Speciators': Evolutionary Dynamics Of A Geographic Radiation Of Island Kingfishers (Todiramphus), Jenna Merle Mccullough

Biology ETDs

The paradox of the ‘Great Speciators’ describes a biogeographic pattern in which geographically widespread lineages have strong overwater dispersal capabilities, yet exhibit genetic and phenotypic divergence between islands, suggesting limited dispersal and cessation of gene flow. In my dissertation, I leveraged whole genomes and two comprehensive trait datasets of dispersal ability and plumage coloration of all described diversity within Todiramphus kingfishers, a rapid radiation of largely island endemic ‘Great Speciators.’ Chapter 1 reveals that whole genome datasets do not outright solve the evolutionary relationships of this clade and that widespread incomplete lineage sorting (ILS) and gene flow are sources of …

Crossing The Ocean: The Importance Of Gene Flow In Island Evolution, Ethan F. Gyllenhaal

Biology ETDs

Islands have long been a critical arena for the development of ecological and evolutionary theory, particular due to persistent open-water gaps between them. In this dissertation I demonstrates how these caps are permeable, which can be leveraged to understand evolution on islands and more broadly. The first chapter develops this connection between ongoing, overwater gene flow and island biogeographic theory, and tests it on an archipelago species. The second take a three-pronged approach in demonstrating how over-water gene flow can bias phylogenetic inference, and how many phylogeographic metrics in islands are likely shaped by long-term gene flow. The final two …

The Descent Of Anolis: Assemblages, Convergence, And Ecomorphological Evolution, Christopher G. Anderson

Biology ETDs

The evolutionary outcomes we observe in modern organisms, particularly associations between phenotypes and environments, have been and remain an invaluable tool in interpreting the biological phenomena that shape our world. In the following chapters, I leverage a comprehensive phylogenetic and morphological dataset for 351 species comprising a diverse group of arboreal lizards, the Anolis clade, to explore how communities and morphologies evolve. First, I characterized patterns among coexisting lineages of Anolis to reveal a general pattern of phylogenetic relatedness among lineages comprising assemblages and identify differences attributable to a biogeographic variable. Then I examined the morphological consequences associated with the …

Resolving The Paradox Of Polyploidy: Underexplored Facets Of Polyploid Plants, Benjamin P. Gerstner

Biology ETDs

Polyploidy, or whole genome duplication, is a common phenomenon in plants, but the establishment and persistence of mixed-ploidy populations remains a paradox. This dissertation explores factors that contribute to the persistence and establishment of mixed-ploidy populations in nature. The first chapter investigates the role of unreduced gametes in neopolyploid establishment and finds that variability in their formation rate can have a significant impact on polyploid establishment and persistence. The second chapter searches for evidence of soil microbes exhibiting ploidy-specificity, a pre-condition for microbe-mediated niche differentiation, a possible stabilizing mechanism contributing to ploidy coexistence. Finally, the third chapter tests for microbe-mediated …

Phylogeographic History Of The Leaf-Eared Mouse, Phyllotis Xanthopygus Complex, Tabitha R. Mcfarland

Biology ETDs

Museum collections provide essential biodiversity sampling needed to understand the species limits, phylogeny, and biogeographic history of mammals, all key features of the foundation for comparative analyses in ecology and evolution. We add to this framework a diverse assemblage of species of leaf-eared mice (genus Phyllotis) in South America and then focus on the Phyllotis xanthopygus complex by combining available mitochondrial sequence (cytochrome b; cytb) data (351 GenBank samples) with 52 newly sequenced museum samples from the northern extent of this complex’s range (51 from Bolivia and 1 from northern Chile) to reconstruct evolutionary relationships using maximum …

Comparative Phylogeography Across Multiple Scales: Small Mammals, Their Ecology, Pathogens, And Drivers Of Diversification, Schuyler W. Liphardt

Biology ETDs

Comparative phylogeography has historically been defined as the study of how genetic variation of co-distributed species has been shaped by biogeographical history. This is a mature field of study out of which several techniques have been developed directed at identifying the role ecology and geography in diversification patterns across time. I employ the tools developed in classical comparative phylogeography across multiple taxonomic scales and across regions that historically have been understudied. My first two chapters study the complex history of host-switching, codiversification, and reassortment of hantaviruses in their mammal hosts across North America. By taking a host-centric comparative phylogeographic approach …

Comparative Genomics Methods And Applications, Emily N. Alden

Biomedical Sciences ETDs

Virtually all fields of biology have benefited from the advancements in comparative genomics technologies, specifically in the study of evolution. In this dissertation I develop and use comparative genomic technologies to investigate the novel SARS-CoV-2 virus, assembly the first genome of the black lace domestic angelfish and identify germline genetic variants associated with altered breast cancer-specific survival. Our genome tiling array for the novel coronavirus presents a rapid and cost-effective method to sequence the entire viral genome and can be used to track the rapid evolution of viral variants in the population. The domestic angelfish is a member of the …

The Phylogeography And Molecular Systematics Of Woodrats (Genus: Neotoma) In The American Southwest, Katrina M. Derieg

Biology ETDs

The American Southwest is a region where many biomes converge, harboring a wide variety of habitats ranging from desert to alpine environments. Habitat heterogeneity and the confluence of multiple species ranges make the American Southwest a biodiversity hotspot. Climate cycling throughout the Quaternary has driven the dynamics of changes in species’ ranges that are recorded by genetic signatures. For example, range expansion may lead to secondary contact between previously isolated populations or species. Contact can result in multiple evolutionary outcomes, including hybridization or the reinforcement and maintenance of independent lineages. I used multi-locus species tree methods to re-examine the nominal …

Introduction To Neutrosophic Genetics, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

Neutrosophic Genetics is the study of genetics using neutrosophic logic, set, probability, statistics, measure and other neutrosophic tools and procedures. In this paper, based on the Neutrosophic Theory of Evolution (that includes degrees of Evolution, Neutrality (or Indeterminacy), and Involution) – as extension of Darwin’s Theory of Evolution, we show the applicability of neutrosophy in genetics, and we present within the frame of neutrosophic genetics the following concepts: neutrosophic mutation, neutrosophic speciation, and neutrosophic coevolution.

Evolutionary Ecology Of Host-Parasite Relationships: Role Of Host Ecology, Phylogeny, And Demographics In Shaping Parasite Evolution, Erika Taylor Gendron

Biology ETDs

Host-parasite systems exist across complex and ecologically heterogeneous landscapes, and may occur across taxonomically and ecologically disparate host species. Under these conditions, mechanisms underlying microevolutionary processes (i.e. gene flow, genetic drift) are not always clear, and may be mediated by numerous co-occurring factors specific to individual hosts. Host traits such as host immunology, demographics, phylogeny and ecology may act in concert to shape host-parasite relationships, and ultimately evolutionary processes. The research described herein used phylogeographic, phylogenomic, and population genetic methods to further understanding of how host traits impact the evolutionary ecology of trematode systems, using avian schistosomes (Digenea: Schistosomatidae) as …

Dynamics Of Avian Elevational Ranges Reveal Hidden Evolutionary Forces, Chauncey R. Gadek

Biology ETDs

The distribution of life across the Andes mountains reflects historical elevational-range contraction and expansion. Whereas contraction implies specialization, expansion requires overcoming hidden barriers. Three eco-evolutionary phenomena may drive patterns in rates of elevational range evolution: (1) The Dobzhansky-MacArthur Phenomenon (DMP) predicts lower rates of upward expansion with harsher physical conditions, while downward expansion increases with lower diversity; (2) the evolutionary tendency toward specialization predicts contraction increases when ranges are broad; and (3) natural selection for respiratory performance could suppress expansion across mid-elevations due to gene-environment mismatch. We modeled elevational range shifts of Neotropical landbirds. Contrary to the DMP, upward expansion …

Mixing It Up: The Impact Of Episodic Introgression On The Evolution Of High-Latitude Mesocarnivores, Jocelyn P. Colella

Biology ETDs

At high latitudes, climatic oscillations have triggered repeated episodes of organismal divergence by geographically isolating populations. For terrestrial species, extended isolation in glacial refugia – ice-free regions that enable terrestrial species persistence through glacial maxima – is hypothesized to stimulate allopatric divergence. Alternatively, upon glacial recession, divergent populations expanded from independent glacial refugia and often contacted other diverging populations. In the absence of reproductive isolating mechanisms, this biogeographic process may trigger hybridization and ultimately, gene flow between divergent taxa. My dissertation research aims to understand how these episodic periods of isolation and contact have impacted the evolution of high latitude …

Genomics Based Approaches To Fungal Evolution, Aaron J. Robinson, Donald O. Natvig

Biology ETDs

Advances in DNA sequencing and data analysis make it possible to address questions in population genetics and evolution at the genomic level. Fungi are excellent subjects for such studies, because they are found in diverse environments, have short generation times, can be maintained in culture and have relatively small genomes. My research employed genetic approaches using a variety of sequencing technologies and methods of analysis to explore questions in fungal evolution.

In one study, I explored the genetics behind differences in thermotolerance between isolates of Neurospora discreta from Alaska and New Mexico. Isolates from the two states exhibited differences in …

The Evolution Of Diet Breadth In Melissodes Bees (Apidae: Eucerini), Karen W. Wright

Biology ETDs

The relationship between phytophagous insects and their host plants has interested scientists since Darwinian times. Using modern phylogenetic inference, we are able to investigate these patterns using, not only the phylogenies of the insects, but the evolutionary relationships among the plants they feed on as well. The relationships between bees and the plants they pollinate were traditionally seen as mutualistic and were treated separately from the research investigating the antagonistic relationships between phytophagous insects and their host plants. However, recent phylogenetic studies have made great progress including bee-host relationships in with the larger body of work on phytophagous insects.

The …

The Paradoxical Giant Hummingbird: Comparison Of Andean And Coastal Subspecies With Respect To Blood, Migration, And Genes, Jessie L. Williamson

Shared Knowledge Conference

The Giant Hummingbird (Patagona gigas) is twice as large as the next largest hummingbird species and has long been considered paradoxical with respect to flight biomechanics. It is also an extreme outlier in other respects. For example, it is the only hummingbird species that breeds above 4,000 m elevation and also along the beaches of the Pacific Ocean. The high Andean populations of Giant Hummingbird (P. g. peruviana) that we have studied previously have a beta-hemoglobin genotype (serine at beta-hemoglobin A positions 13 and 83) that is characterized by high O2-affinity and is only shared with four unrelated hummingbird taxa …

Genomic Signatures Of Adaptive Evolution, Jessica A. Weber

Biology ETDs

Comparative genomics has revolutionized virtually all fields of biology including the study of evolution. In this dissertation, I used next-generation sequencing to explore the evolutionary histories and adaptive evolution of a diverse set of taxa. Comparisons ranged across time scales, from population-level genetic diversity studies to questions spanning the deepest branches of the metazoan lineage. Whole genome sequencing of 50 unrelated Korean individuals revealed that Koreans have a distinct genetic history from the Chinese and Japanese populations. Our Korean-specific variome database was used to identify novel disease-causing variants in the Korean population, highlighting the value of high-quality ethnic variation databases …

Systematics And Diversification Of The Pantropical Avian Order Coraciiformes, Jenna Merle Mccullough

Biology ETDs

How and why species diversify is a central theme of evolutionary biology. Species-rich, morphologically diverse, pantropical clades provide rare opportunities to explore questions about drivers of diversification in the tropics. Here, we present the first complete species tree of Coraciiformes (6 families, ~177 species of kingfishers, motmots, bee-eaters, and allies), produced with thousands of ultraconserved elements. We recovered a well-supported tree which shows that there are two clades within Coraciiformes: 1) bee-eaters sister to rollers + ground- rollers and 2) todies sister to motmots + kingfishers. We estimated the biogeographical history of the group, explored bill shape evolution with a …

Understanding Patterns Of Diversity And Evolution In Mainland Anolis Lizards, Levi Nathaniel Gray

Biology ETDs

Patterns of organismal diversity and evolution are often difficult to interpret with a high level of confidence. The number of mechanisms and processes that contribute to shaping patterns of diversity is extensive and is reflected in the many methods researchers have used to infer causation. Taxonomic groups that are well-studied can offer more precise interpretation of pattern and process due to the considerable amount of research addressing ecology, natural history, and behavior of the organisms.

In this dissertation, I explore patterns of phylogenetic and phenotypic variation in Anolis lizards (anoles) by testing hypotheses that could have led to the observed …

Immunology Of The Gray Short-Tailed Opossum During Pregnancy And Prenatal Development, Victoria L. Hansen

Biology ETDs

Vertebrate species that bear live young have overcome the evolutionary challenge of maintaining both a functional adaptive immune system and viviparous life cycle. In normal pregnancy, viviparous mothers are able sustain and nourish a fetus that is genetically half non-self without mounting an immunological attack. In 1953 Sir Peter Medawar brought attention to the “enigma of the fetal graft” and immunologists have been puzzling out the intricacies of fetal tolerance ever since. Although viviparity has evolved in all jawed vertebrate lineages aside from Aves, the vast majority of reproductive immunology research has been limited to eutherian mammals. There are insights …