Evolution Commons^™

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 …

Co-Divergence Of Lemur Hosts And Gut Microbiomes Across Multiple Evolutionary Scales, Mariah E. Donohue

Theses and Dissertations--Biology

This dissertation bridges micro- and macroevolutionary approaches to understand the co-diversification of animal hosts and their gut microbiomes at different evolutionary timescales. I examined these dynamics using wild lemurs, a diverse Primate clade endemic to the island of Madagascar.

First, I tested the relative effects of host phylogenetic relationships, diet, and habitat in shaping the gut microbiome through deep evolutionary time and across distinct microbial kingdoms. I designed a natural experiment sampling feces from rainforest and dry forest lemur communities with similar phylogenetic assemblages and considerable variation in dietary strategy. Then, I amplified and sequenced two metabarcoding genes, the V4 …

The Evolutionary Causes And Consequences Of Mammalian Hybridization, Kelsie E. Hunnicutt

Electronic Theses and Dissertations

The natural recombination of divergent genomes within hybrid offspring provides windows through which we can study evolutionary processes and the dynamics of speciation. In this work, I use a combination of comparative and population genomics on both laboratory crosses of divergent rodent lineages and a hybrid zone of cottontail rabbits in the wild to study the causes and consequences of hybridization in mammals. Hybrid sterility is a common reproductive barrier between species that tends to preferentially manifest in the heterogametic sex and frequently genetically maps to the sex chromosomes. Thus, the sex chromosomes appear to play a special role in …

Morphological Variation And Community Science In Orthoptera, Amy Byerly

Electronic Theses and Dissertations

Patterns of morphological divergence across species’ ranges provide insight into local adaptation and speciation. Here, we compare phenotypic divergence among 4,221 crickets from 337 populations of two related species of field cricket, Gryllus firmus and G. pennsylvanicus and their hybrids. We find that these species differ across their geographic range in key morphological traits, such as body size and ovipositor length, and we directly compare phenotype with genotype for a subset of crickets demonstrating nuclear genetic introgression, phenotypic intermediacy of hybrids, and essentially unidirectional mitochondrial introgression. We discuss how these morphological traits relate to life history differences between the species. …

Dynamics Of Hybrid Zones At A Continental Scale, Bradley T. Martin

Graduate Theses and Dissertations

Hybridization has traditionally been viewed as a happenstance that negatively impacts populations, but is now recognized as an important evolutionary mechanism that can substantially impact the evolutionary trajectories of gene pools, influence adaptive capacity, and contravene or reinforce divergence. Physiographic processes are important drivers of dispersal, alternately funneling populations into isolation, promoting divergence, or facilitating secondary contact of diverged populations, increasing the potential for hybridization. In North America, glacial-interglacial cycles and geomorphological changes have provided a dynamic backdrop over the last two million years that promoted such oscillations of population contraction and expansion. These biogeographic processes have resulted in regional …

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.

A Taxonomic Revision Of The Genus Burmeistera (Campanulaceae) In Ecuador, Brock Mashburn

Theses

The genus Burmeistera (Campanulaceae) consists of approximately 120 species of herbaceous trailing shrubs, found mostly in cloud forests from Guatemala to Peru. Taxonomic work is difficult for the genus because of its relatively recent diversification (5–12 mya) and the morphological lability of its species. The last monograph for the genus was completed in 1943, followed periodically by country-level treatments. For Ecuador, the most recent treatment of Burmeistera was nearly 40 years ago, in Stig Jeppesen’s 1981 treatment in the Flora of Ecuador. Jeppesen’s treatment recognized 32 species and subspecies. Since then, nine new species have been described and hundreds of …

Phylogenomics And Geometric Morphometrics Define Species Flocks Of Snowtrout (Teleostei: Schizothorax) In The Central Himalayas, Binod Regmi

Graduate Theses and Dissertations

Schizothorax (Snowtrout) is a genus of medium-sized minnows (Cypriniformes) inhabiting glacier-fed streams, rivers, and lakes in the Himalayas. There are more than 30 species of Schizothorax across the region. The speciation and diversity of the Snowtrout in the vast hinterlands of the Himalayan Region has not been fully explored. Three species in Lake Rara, Western Nepal are considered a species flock, comprising endemic ecotypes that are morphologically differentiated and reproductively isolated.

My dissertation research examined the diversity of Schizothorax in the Central Himalayan region and evolutionary relationships among species distributed in the Tibet, Central and Southeast Asia. Chapter I describes …

Comparative Phylogeography, Taxonomy, And Neuroanatomy Of Montane Chameleons In The Albertine Rift, Central Africa, Daniel Hughes

Open Access Theses & Dissertations

How do traits vary across the tree of life? Our ability to address this question is diminished if: A taxonomic group has a poorly sampled phylogeny, a species goes extinct before their systematic position is resolved, or a trait is inadequately characterized for detailed studies. In the current era of mass extinction, it is imperative to not only accelerate species discovery through traditional studies in taxonomy and expeditionary research, but also to increase rescue efforts for all types of data before poorly understood species and potentially undescribed traits are lost. Here, an integrative taxonomic approach was used and novel methods …

Cryptic Diversity And Discordance In Single‐Locus Species Delimitation Methods Within Horned Lizards (Phrynosomatidae: Phrynosoma), Christopher Blair, Robert W. Bryson Jr.

Publications and Research

Biodiversity reduction and loss continues to progress at an alarming rate, and thus there is widespread interest in utilizing rapid and efficient methods for quantifying and delimiting taxonomic diversity. Single-locus species-delimitation methods have become popular, in part due to the adoption of the DNA barcoding paradigm. These techniques can be broadly classified into tree-based and distance-based methods depending on whether species are delimited based on a constructed genealogy. Although the relative performance of these methods has been tested repeatedly with simulations, additional studies are needed to assess congruence with empirical data. We compiled a large data set of mitochondrial ND4 …

Ecological Niche Modeling Of The Genus Papio, Amanda J. Fuchs

Theses and Dissertations

Ecological niche modeling investigates how climatic variables have influenced taxonomic diversity in Papio. Models performed well suggesting climatic variables influence the distribution of baboon species. Niche overlap among all possible pairs of taxa determined that species exhibited significantly different niches. The results of these models support a parapatric speciation scenario.

Patterns Of Morphological And Molecular Evolution In The Antillean Tree Bat, Ardops Nichollsi (Chiroptera: Phyllostomidae), Roxanne J. Larsen, Peter A. Larsen, Caleb D. Phillips, Hugh H. Genoways, Gary G. Kwiecinski, Scott C. Pedersen, Carleton J. Phillips, Robert J. Baker

University of Nebraska State Museum: Mammalogy Papers

Species endemic to oceanic islands offer unique insights into the mechanisms underlying evolution and have served as model systems for decades. Often these species show phenotypic variation that is correlated with the ecosystems in which they occur and such correlations may be a product of genetic drift, natural selection, and/or environmental factors. We explore the morphologic and genetic variation within Ardops nichollsi, a species of phyllostomid bat endemic to the Lesser Antillean islands. Ardops nichollsi is an ideal taxon to investigate the tempo of evolution in Chiroptera, as it: is a recently derived genus in the family Phyllostomidae; contains …

The Maintenance Of Phenotypic Divergence Through Sexual Selection: An Experimental Study In Barn Swallows Hirundo Rustica, Rebecca Safran, Yoni Vortman, Brittany R. Jenkins, Joanna K. Hubbard, Matt Wilkins, Rachel J. Bradley, Arnon Lotem

School of Biological Sciences: Faculty Publications

Previous studies have shown that sexual signals can rapidly diverge among closely related species. However, we lack experimental studies to demonstrate that differences in trait-associated reproductive performance maintain sexual trait differences between closely related populations, in support for a role of sexual selection in speciation. Populations of Northern Hemisphere distributed barn swallows Hirundo rustica are closely related, yet differ in two plumage-based traits: ventral color and length of the outermost tail feathers (streamers). Here we provide experimental evidence that manipulations of these traits result in different reproductive consequences in two subspecies of barn swallow: (H. r. erythrogaster in North …

Chromosomal Rearrangements Directly Cause Underdominant F1 Pollen Sterility In Mimulus Lewisii-M. Cardinalis Hybrids, Angela M. Stathos

Graduate Student Theses, Dissertations, & Professional Papers

Chromosomal rearrangements can contribute to the evolution of postzygotic reproductive isolation directly, by disrupting meiosis in F₁ hybrids, or indirectly, by suppressing recombination among genic incompatibilities. Because direct effects of rearrangements on fertility imply fitness costs during their spread, understanding the mechanism of F₁ hybrid sterility is integral to reconstructing the role(s) of rearrangements in speciation. In hybrids between monkeyflowers Mimulus cardinalis and M. lewisii, rearrangements contain all quantitative trait loci (QTLs) for both premating barriers and pollen sterility, suggesting that they may have facilitated speciation in this model system. I used artificial chromosome doubling and …

Phylogeny And Systematics Of Panaspis And Afroablepharus Skinks (Squamata: Scincidae) In The Savannas Of Sub-Saharan Africa, Maria Fernanda Medina

Open Access Theses & Dissertations

African snake-eyed skinks are relatively small lizards of the genera Panaspis and Afroablepharus. The allocation of these genera was frequently rearranged in the 20th century based on morphology, ecology and biogeography. Members of these genera occur primarily in savanna habitats throughout sub-Saharan Africa and include species that have highly conserved morphology, which poses a challenge for taxonomic studies. We sequenced two mitochondrial (16S and cyt b) and two nuclear genes (PDC and RAG1) from 91 Panaspis and Afroablepharus samples from various localities in eastern, central and southern Africa. Concatenated gene-tree and divergence dating analyses were conducted to infer phylogenies and …

Phylogenetic Relationships Within Columnea Section Angustiflorae: Insights Into Forces Driving Speciation, Lacie Janelle Schulte

Boise State University Theses and Dissertations

Determining the specific factors that played a role in speciation previously took extensive resources that made such studies nearly intractable. Despite the difficulties presented by speciation studies, we are still interested in determining what forces drive the process of evolution to gain a better understanding of divergence among species. Advances in technology allow for a new approach to speciation studies, beginning with molecular phylogenetic analyses that identify the species within a monophyletic clade and generate a species-level phylogeny. Molecular data are an independent source of data and provide a phylogeny to map both morphological characters and ecological parameters. Identifying patterns …

On The Monkeys Of The Amazon (1852), Alfred Russel Wallace

Alfred Russel Wallace Classic Writings

No abstract provided.

On The Tendency Of Varieties To Depart Indefinitely From The Original Type (1858), Alfred Russel Wallace

Alfred Russel Wallace Classic Writings

No abstract provided.

The Emergence Of Sex, Ursula Goodenough

Biology Faculty Research

Biological traits, the foci of natural selection, are by definition emergent from the genes, proteins, and other “nothing-buts” that constitute them. Moreover, and with the exception of recently emergent “spandrels,” each can be accorded a teleological dimension—each is “for” some purpose conducive to an organism's continuation. Sex, which is “for” the generation of recombinant genomes, may be one of the most ancient and ubiquitous traits in biology. In the course of its evolution, many additional traits, such as gender and nurture, have emerged. Patterns of sexual exchange are the basis for patterns of biological evolution and are central to the …