Comparative and Evolutionary Physiology Commons^™

Study Of The Brain Anatomy Of Three Extinct Marsupials: Thylacinus Cynocephalus, Thylacoleo Carnifex, And Silvabestius Johnnilandi, Francisco Garcia

Honors Program Theses and Research Projects

Marsupials are pouched mammals that today are mainly found in Australasia and South America. Marsupials have proven to be quite intriguing to evolutionary biologists who note how some marsupials resemble placentals in anatomy due to convergent evolution, with both marsupials and placentals filling similar niches in their respective environments. As of today, studies interested in marsupial brain evolution have published descriptions of cranial endocasts for several species of marsupials, with the number of descriptions seeing a massive boost over the last 20 years with the arrival of CT imaging technology. However, no comprehensive study of brain evolution in marsupials has …

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 …

Impact Of Thermal-Hydric Stress Of Physiological Performance And Mating Behavior Of Fiddler Crabs, Talene G. Yeghissian

Dissertations

Fiddler crabs live on the edge of their thermal tolerance limits, balancing the need to thermoregulate with the need to mate. Previous research suggests that increased temperature reduces fiddler crab surface activity time, thus decreasing mating opportunities, throughout the range species with greatest impacts to low latitude populations. The less studied missed mating opportunities associated with behavioral compensation for thermal stress are crucial to understanding species vulnerability to climate change. In this dissertation, I describe a combination of experimental and observational approaches in the field and in the laboratory to investigate the physiological and behavioral responses of fiddler crabs to …

Investigating The Adaptive Potential Of Leaf Variegation In Two Dimorphic Hexastylis Species, Cierra N. Sullivan

All Dissertations

Variegated leaves with disjointed, patterned coloration of the leaf blade are often hypothesized to have decreased photosynthetic capacity in comparison to uniformly colored leaves. Yet, many forest understory plants in tropical, subtropical, and temperate climates possess leaf variegation. Moreover, mixed findings from previous research on the physiological impacts of leaf variegation suggest variegation is adaptative under certain environmental conditions despite decreased photosynthetic tissue area. I take an eco-physiological approach to investigate agents of selection maintaining a leaf variegation polymorphism in Hexastylis, which has both quantitative and qualitative variation in variegation. First, I conduct field surveys of morph frequencies, quantitative …

Patterns And Potential Mechanisms Of Phenotypic Changes In Urban Small Mammals, Leslie Lopez

Master's Theses

Urbanization is an example of human induced rapid environmental change that can have wide-reaching ecological effects, including habitat destruction, fragmentation, and alteration of local climates. Effects of urbanization have been shown to impact wildlife, as disturbances resulting from urbanization can create novel environments and selective pressures that could lead to changes in morphology, physiology, or both. Small mammals such as rodents are an ecologically important set of wildlife species because they are a key prey item for several predators, hold strong influence over plants as a primary consumer, and some species carry and transmit major human and animal diseases. Previous …

Paralog Switching Facilitates Diadromy: Ontogenetic, Microevolutionary And Macroevolutionary Evidence, Rebecca S. Colby, Stephen D. Mccormick, Jonathan P. Velotta, Elizabeth Jockusch, Eric T. Schultz

EEB Articles

Euryhalinity is present in diverse aquatic taxa and requires flexible osmoregulation to field the challenges posed by differing salinities. Na+, K+-ATPase (NKA) is a ubiquitous ion pump in the gills of fishes and, for some species, paralogs of the catalytic -subunit (NKA 1a and NKA 1b) exhibit reciprocal expression between fresh- and seawater, termed paralog-switching. We investigated the expression and evolution of NKA paralogs in Alewife (Alosa pseudoharengus), a euryhaline and migratory fish. Comparisons between landlocked and diadromous life history forms and migrant and pre-migrant ontogenetic stages were used to study shifts in NKA paralog expression related to freshwater or …

Robust Phylogenetic Regression, Richard Adams, Zoe Cain, Raquel Assis, Michael Degiorgio

Entomology and Plant Pathology Faculty Publications and Presentations

Modern comparative biology owes much to phylogenetic regression. At its conception, this technique sparked a revolution that armed biologists with phylogenetic comparative methods (PCMs) for disentangling evolutionary correlations from those arising from hierarchical phylogenetic relationships. Over the past few decades, the phylogenetic regression framework has become a paradigm of modern comparative biology that has been widely embraced as a remedy for shared ancestry. However, recent evidence has shown doubt over the efficacy of phylogenetic regression, and PCMs more generally, with the suggestion that many of these methods fail to provide an adequate defense against unreplicated evolution—the primary justification for using …

Comparing Ionoregulation And Modes Of Nitrogen Excretion Across The Life Cycle Of Parasitic And Non-Parasitic Lamprey Species, Shannon Davidson

Theses and Dissertations (Comprehensive)

Abstract

Ionoregulation and nitrogenous waste (N-waste) metabolism in fishes has been extensively documented in teleosts and elasmobranchs, but less so in lampreys (Petromizontiformes). All lamprey species undergo metamorphosis which drastically changes their physiology and modes of feeding. However, differences in ionoregulatory mechanisms due to anadromous versus non anadromous life history strategies emerge following metamorphosis in different lamprey species. Furthermore, some species, such as anadromous juvenile sea lamprey (Petromyzon marinus), are parasitic and migrate to seawater (SW) to ingest blood protein from host fishes, while juveniles of freshwater (FW), non-parasitic species, such as the American brook lamprey …