Ecology and Evolutionary Biology Commons^™

Long-Term Spatiotemporal Change In Coral Reef Fish Populations And Communities In The Philippines, John Christopher Whalen

Biological Sciences Theses & Dissertations

The Visayas Region of the Philippines is a global epicenter of marine fish biodiversity. Hypotheses attribute this peak of species richness within the Coral Triangle to processes that occur at geological time scales. However, changes in biodiversity may occur on ecological time scales, allowing for the assessment of the potential impact of anthropogenic activities. Recent declines in genetic, species, and ecosystem diversity have been observed in the tropics, including the Philippines. Within the Philippines the Visayas Region is considered the epicenter of species adversity due to anthropogenic stressors such as habitat degradation, overfishing, and harvesting individuals for the aquarium trade. …

From Shallow To Upper Mesophotic Reefs: Examining Environmental Influences On Coral Physiology And Thermal Tolerance, Katherine Eileen Parker

Biological Sciences Theses & Dissertations

Coral reefs are increasingly threatened by rising ocean temperatures, yet coral thermal tolerance varies widely across species, populations, and environments. This dissertation investigates the biological and environmental mechanisms underlying coral thermal resilience, with a focus on symbiosis dynamics, photoacclimation, and the interaction between light and heat stress across environmental gradients. Specifically, it examines how coral-Symbiodiniaceae partnerships respond to thermal stress using the Coral Bleaching Automated Stress System (CBASS) across contrasting thermal and light environments, spanning population-level differences, depth-associated variation, and experimental manipulation of light during acute heat stress. First, thermal thresholds and transcriptomic dynamics were examined in two wild Porites …

Extinction Risk Of Coral Reef Fishes In The Philippine Marine Ornamental Trade, Jemelyn Grace Baldisimo Sepulveda

Biological Sciences Theses & Dissertations

Coral reef ecosystems in the Philippines face severe threats from intense fishing and habitat degradation. This dissertation evaluated the extinction risk of fishes in the Philippine Marine Aquarium Trade (MAT) using Productivity Susceptibility Analysis (PSA) and temporal genomics. A global PSA framework was modified by including local susceptibility factors. Of the 103 species evaluated, six were categorized as highly vulnerable and 62 as moderately vulnerable, revealing increased local vulnerability and underscoring the importance of local assessments to guide conservation efforts.

Temporal genomics compared historical (1908–1909 U.S.S. Albatross Expedition) and contemporary populations of the MAT-targeted Sphaeramia nematoptera and Pseudanthias squamipinnis, …

The Role Of Phenotypic Plasticity And Bet-Hedging In Coping With Unpredictable Temperature Fluctuations In The Marine Annelid Ophryotrocha Labronica, Gabrielle Dawn Newton

Biological Sciences Theses & Dissertations

Coastal ecosystems are increasingly exposed to unpredictable temperature fluctuations, potentially favoring strategies that buffer populations against environmental uncertainty. This study examines how phenotypic plasticity and diversified bet-hedging contribute to variation in life-history traits under differing thermal predictability in the marine annelid Ophryotrocha labronica. After three generations at 24 °C, broods were reared for three generations under four thermal regimes: constant 24 °C (C24), constant 27 °C (C27), predictable fluctuations (Fp), and unpredictable fluctuations (Fu). Survival was assessed before and after acclimation to evaluate selective pressure among regimes. Age at maturity, fecundity, and growth rate were used to quantify plasticity (trait …

Endotherm Energetics Under Environmental And Physiological Constraints, Zachary Andrew David

Biological Sciences Theses & Dissertations

Metabolic rate governs how animals allocate energy toward maintenance, activity, growth, and reproduction, linking physiology to environmental context. This dissertation investigates how two endothermic mammals regulate metabolic rate in response to environmental variability, focusing on thermoregulatory flexibility and physiological constraints. Using flow-through respirometry, I measured resting metabolic rates (RMRs) in two complementary systems: tropical bears housed in semi-natural outdoor enclosures and marsh rice rats (Oryzomys palustris) exposed to controlled thermal treatments. Asiatic black bears (Ursus thibetanus) exhibited unexpectedly low mass-specific metabolic rates even under high ambient temperatures, yet their RMR increased with temperature, suggesting proximity to their …

Effects Of Sediment Composition On Spartina Alterniflora And Juncus Roemerianus Productivity In Coastal Virginia: A Thin-Layer Sediment Placement Experiment, Caitlin Hemphill

Biological Sciences Theses & Dissertations

Climate change poses a major threat to the health of estuaries and their coastal wetland systems. The Chesapeake Bay’s coastal salt marshes are at high risk of inundation due to sea-level rise and land subsidence. Restoration techniques for maintaining coastal marsh resistance to sea-level rise are being developed and refined, with thin layer placement (TLP) emerging as a feasible solution in many areas of the United States. Despite TLPs use across the country, additional research is needed on species-specific responses, sediment types, and geographically focused studies in the lower Chesapeake Bay. My research addresses these gaps by combining both greenhouse …

A Dendrochronological Analysis Of Longleaf And Associated Pines From The Blackwater Ecological Preserve In Southeastern Virginia, Sarah Durham

Biological Sciences Theses & Dissertations

The field of dendrochronology utilizes annual tree ring growth data to create chronologies, which function as proxies to measure the effect of climate on radial growth. In the southeastern United States, dendrochronological studies involving the effect of climate on the growth of Pinus species exist, but significant gaps persist. For this study, I: 1) created chronologies of earlywood, latewood, and total ring-width growth for longleaf pine (Pinus palustris Mill.), loblolly pine (P. taeda L.), and pond pine (P. serotina Michx.) and 2) conducted a climate analysis on each species to determine how climatic factors affected radial …

The Ecological Applications Of Δ17O: Validating A Novel Technique For Assessing Animal Metabolism And Water Intake, Zachary Taylor Steele

Biological Sciences Theses & Dissertations

Animals obtain water via different processes such as drinking, consuming food, and through metabolic processes like at the end of the electron transport chain when atmospheric oxygen is combined with hydrogen to form ‘cytochrome oxidase water’. Assessing animal water flux and metabolism has mainly been conducted via stable isotope analysis (SIA) of biological samples using hydrogen (²H) and oxygen isotopes (¹⁶O, ¹⁷O, and ¹⁸O; Δ¹⁷O), typically using enriched isotope tracers. However, natural abundance isotope modeling offers an approach for conducting SIA of biological samples that differs because it relies on the unique, …

Maneuverability Of Cuttlefish And Squid: An Integrated Kinematic And Hydrodynamic Analysis, Alissa Marie Ganley

Biological Sciences Theses & Dissertations

Turning is important for life underwater, playing roles in predator avoidance, prey capture, locomotion, and communication. While turning abilities have been explored in many taxa, little is known about maneuverability of cephalopods, such as cuttlefishes and squids. The objectives of this dissertation include: (1) quantifying the turning abilities of cuttlefish hatchlings and determining whether there are species-specific differences; (2) examining the turning capabilities of adult cuttlefishes, with the goal of comparing adult performance with that of conspecific hatchlings; and (3) quantifying how adult neritic squids perform turns to provide a broader context of maneuvering strategies in cephalopods. To investigate turning, …

Influence Of Abiotic Drivers And Plant Community Interactions On Bald Cypress (Taxodium Distichum) Seedlings: Implications For Restoration, Victoria Ellis

Biological Sciences Theses & Dissertations

Forested freshwater wetlands are valuable ecosystems that provide habitat for numerous species, sequester carbon, and act as sinks for excess water and nutrients. Historically, these ecosystems have been heavily degraded by anthropogenic activities leading to loss of ecosystem services and a desire to restore freshwater forested wetland habitat. Thus, science-backed approaches for the restoration of freshwater forested wetlands are necessary to ensure restoration goals are met. This body of research employed the Stress Gradient Hypothesis to test whether a multi-species planting approach using Juncus effusus (L.) (soft rush) could facilitate the survival of Taxodium distichum (L.) Rich. (bald cypress) seedlings …

Landscape Genetics Of The Gulf Coast Tick, Amblyomma Maculatum, Sara Simmons Benham

Biological Sciences Theses & Dissertations

Connectivity among populations helps to maintain genetic diversity, population stability, and resilience. The Gulf Coast tick, Amblyomma maculatum, is a vector of the pathogen Rickettsia parkeri. Persistence of tick populations with high rates of R. parkeri infection poses health risks to humans and animals. Mitochondrial haplotypes were characterized by sequencing a fragment of the mitochondrial 16S rRNA gene. A comparative study of A. maculatum and Amblyomma americanum was conducted to identify similar and unique patterns between the species within the same region. Next, I compared A. maculatum sites across three different regions of the United States. This work …

Nestedness And Modularity Of Avian Metacommunities Across Gradients Of Chesapeake Bay Island Characteristics, Grant Walter Bowers

Biological Sciences Theses & Dissertations

Islands are not only great models for understanding the ways in which communities are linked by the dispersal of their members to form metacommunities, but are of particular interest to conservationists. One important aspect of metacommunity structure is the degree of nestedness—whether or not less speciose communities are perfect subsets of more speciose communities. Another important metric of metacommunity structure is modularity—the degree to which communities belong to modules composed of other communities that share the same species but have little species overlap with communities from different modules. Environmental gradients have received insufficient attention as predictors of metacommunity nestedness and …

The Influences Of Disperser Behavior, Host Availability, And Environmental Conditions On The Distribution Of Oak Mistletoe [Phoradendron Leucarpum (Raf.) Reveal & M. C. Johnst.] In Eastern Virginia And North Carolina, Nicholas Pearce Flanders

Biological Sciences Theses & Dissertations

Mistletoes are shrubs that typically parasitize the branches of host trees and rely on avian frugivores for seed dispersal. Because mistletoes are restricted to a narrow range of suitable recruitment sites and avian frugivores are more visible than other guilds of seed dispersers, mistletoe-frugivore systems afford opportunities for assessing the roles of dispersal limitation and local environment in determining plant distribution. These mechanisms have been proposed as determinants of the observed association of oak mistletoe [Phoradendron leucarpum (Raf.) Reveal & M. C. Johnst.] with forested wetlands in eastern Virginia and North Carolina, USA. I tested the alternative hypothesis that …

Temporal Dynamics And Seed Dispersal In Plant-Frugivore Communities Of The Dominican Republic, Spencer Christian Schubert

Biological Sciences Theses & Dissertations

Plant-animal mutualisms are a foundational component of biodiversity in terrestrial ecosystems. Most tropical forest plants have adapted to produce fleshy fruits to attract frugivorous animals to disperse seeds. Interaction patterns among plant taxa and their seed dispersers are driven by a complex suite of factors involving their evolutionary history and environmental context, and the structure of these mutualistic networks are theoretically tied to their ecological function. I carried out a series of field studies to investigate the temporal dynamics of mutualistic interactions of plant and avian frugivore communities in the central Dominican Republic and how their characteristics affect seed dispersal …

Efficacy Of Sediment Contaminant Remediation Of The Benthos In A Segment Of The Southern Branch Of The Elizabeth River, Colton Martin

Biological Sciences Theses & Dissertations

The bottom sediment of the Southern Branch of the Elizabeth River, a tributary of Chesapeake Bay, was historically contaminated with hydrocarbons from industrial sources especially wood treatment facilities. The Elizabeth River Project selected a section of the bottom off Money Point in the Southern Branch for a sediment contaminant remediation effort. Prior to initiation of remediation efforts, a survey occurred in summer 2010 to characterize the ecological condition of the benthic communities off Money Point compared to benthic communities of a benthic region across the channel and northwest of Money Point near Blows Creek. That study characterized the benthos of …

The Role Of Backreef Soundscapes And Their Spatial Structure For Recruitment Of Tropical Marine Larvae, Emily R. Anderson

Biological Sciences Theses & Dissertations

Underwater sound is a cue used by many marine larvae to orient to coastal habitats including backreef, sponge-dominated hardbottom habitat in the Florida Keys (Florida, USA) – a particularly “noisy” coastal habitat. However, the distance over which acoustic cues are attractive to settlement-stage larvae - is generally unknown. I examined this phenomenon in a region of the Florida Keys where mass sponge die-offs have diminished both underwater soundscapes and larval settlement. The absence of pronounced hardbottom-associated sound over such a large area allowed me to experimentally test in situ the response of fish and invertebrate larvae to broadcasted sounds at …

Population Dynamics And Dispersal Coalitions In The Cooperatively Breeding Acorn Woodpecker, Natasha Hagemeyer

Biological Sciences Theses & Dissertations

Dispersal is a critical life-stage with consequences not only for the individual, but for population dynamics and thus the fate of the whole species. The creation of dispersal coalitions can lead to complex outcomes and affect how changes in abundance occur on the landscape. I examined population dynamics and dispersal coalitions in a population of cooperatively breeding acorn woodpeckers in central California, USA. Using a 34-year dataset on occupancy and abundance, I determined that increases in abundance were determined by dispersal to new locations. This resulted in increased occupancy, rather than increases in group size and larger coalitions. I then …

A Test Of Rad Capture Sequencing On Ethanol-Preserved Centennial And Contemporary Specimens Of Philippine Fishes, Madeleine I. Kenton

Biological Sciences Theses & Dissertations

Understanding the relationship between ecological characteristics and genetic change in natural populations in different time scales can reveal how anthropogenic stressors affect natural populations and can improve the success of conservation strategies. The purpose of the Philippines Partnerships for International Research and Education (PIRE) project is to examine levels of genetic change between historical fish samples collected by the USS Albatross expedition in the early 1900s in the Philippines and contemporary populations collected at the same localities. This study tests genetic protocols to process historical and contemporary DNA for simultaneous comparison. Two DNA library preparation methods, single digest RADseq (“un-baited” …

Assessment Of Factors Influencing Migratory Landbird Use Of Forested Stopover Sites Along The Delmarva Peninsula During Autumn Migration, J. Andrew Arnold

Biological Sciences Theses & Dissertations

Autumn migration is a time when billions of birds move from breeding grounds in North America to wintering grounds in Central and South America, with many individuals relying on stopover habitats en route for resting and refueling purposes. These stopover sites are critical to the survival of the hundreds of species of migratory landbirds that migrate annually, and thus identifying important stopover sites is a high priority for conserving such taxa. The Delmarva Peninsula; a coastal region of Delaware, Maryland, and Virginia along the mid-Atlantic flyway; consists of forested habitats with ample food and shelter that likely serves as quality …

Not Too Hot, Not Too Cold, But Moderately Variable: The Influence Of Environmental Variability On Coral Thermal Tolerance, Courtney Nicole Klepac

Biological Sciences Theses & Dissertations

Anthropogenic climate change is causing an increase in the frequency and severity of marine heat waves, resulting in declining health of coral reef ecosystems worldwide. Coral bleaching events – the breakdown in symbiosis between the coral host and their intracellular photosynthetic algae – are increasingly common in recent years and contribute to widespread losses in coral cover. However, bleaching and heat stress responses vary across spatial scales both within and among coral species. Coral populations native to highly variable environments can have greater bleaching resistance than corals from more stable habitats and corals transplanted into these variable reef sites can …

The Effects Of Hackberry Psyllids On Refueling Migratory Songbirds And Autumnal Seed Rain, Chance H. Hines

Biological Sciences Theses & Dissertations

Hackberry psyllids (Pachypsylla sp) are a galling insect native to North America’s hackberry trees (Celtis sp). Hackberry leaf-galling psyllids are ephemerally abundant during autumn, a period of time when migratory songbirds are traveling from their breeding areas in temperate North America south to their winter ranges. These migrations are energetically taxing and many songbirds fuel their journey with resources like insects and fruits. I captured birds with mist nets, observed foraging behaviors, and captured avian-dispersed fleshy fruit seeds (hereafter, seed rain) rain during the autumn of 2016 and 2017 to determine how hackberry psyllids, an ephemerally …

Diet Analysis Of Stranded Bottlenose Dolphins (Tursiops Truncatus) In Virginia, Kristen Marie Volker

Biological Sciences Theses & Dissertations

This study describes the diet of bottlenose dolphins (Tursiops truncatus) stranded in Virginia via stomach content analysis and considers factors such as proportion of numerical abundance and reconstructed mass, frequency of occurrence, average reconstructed prey size, prey diversity and quantity, and otolith degradation code. Fish size was estimated via regression equations established from local fish collected during the study that derive wet weight directly from otolith length or width. Squid size is estimated from previously published equations. Soniferous fishes dominated the diet, especially Atlantic croaker, spot, and seatrout spp., adding evidence to the theory that bottlenose dolphins passively …

Tick Control Methods For Amblyomma Americanum In Virginia: Applications And Modeling, Alexis Lynn White

Biological Sciences Theses & Dissertations

Tick-borne diseases continue to increase in the United States, and yet no comprehensive method of tick control currently exists. The lone star tick, Amblyomma americanum, is an aggressive human-biting tick and vector of several pathogens which effect both humans and other animals. Standard control methods do not work as well for A. americanum as they do for the more commonly studied blacklegged tick, Ixodes scapularis. TickBot, a tick-killing robot, is a potential method to control A. americanum that lures ticks to its path with carbon dioxide and the ticks die from contact with a permethrin-treated cloth that is …

Global Conservation Status And Threat Patterns Of The World’S Most Prominent Forage Fishes (Teleostei, Clupeiformes), Tiffany L. Birge

Biological Sciences Theses & Dissertations

Conserving biodiversity is one of the greatest ethical responsibilities and challenges humans face. Understanding the conservation status of taxonomic groups provides a systematic way to prioritize efforts to combat biodiversity loss. The 405 species within the order Clupeiformes are the herrings, shads, sardines, anchovies, menhadens and relatives that include many of the most important marine forage fishes. These small, schooling fishes are economically, ecologically and culturally significant globally. Despite their contribution to global fisheries and our increasing reliance on these fishes for food and industrial commodities, they are generally poorly known with limited information regarding basic biology and population trends. …

In Hot Water: Thermal Acclimation Is Insufficient To Save Corals In The Anthropocene, Harmony Alise Martell

Biological Sciences Theses & Dissertations

Scleractinian corals are animal partners in exquisite symbioses with a suite of algal, microbial, fungal and viral associates comprising miniature ecosystems collectively referred to as a holobiont. In recent decades, ocean warming has jeopardized the delicate balance of the very symbioses that have enabled coral survival. Thermal stress causes a reduction of algal symbionts, a phenomenon referred to as ‘coral bleaching’ that represents dysbiosis in the holobiont and often leads to mortality. Current thermal acclimation theory states variation and gradual increases in temperature can ameliorate thermal stress. Indeed, there is evidence some coral species have some capacity to acclimatize to …

Cryptic Herbivorous Invertebrates Restructure The Composition Of Degraded Coral Reef Communities In The Florida Keys, Florida, Usa, Angelo Jason Spadaro

Biological Sciences Theses & Dissertations

Coral reefs have been on a trajectory of decline for nearly a century due to a variety of factors that have contributed to the shift in these communities away from dominance by reef-building corals, with commensurate changes on community composition and function. Florida’s reefs are a compelling example of a degraded system that has undergone a phase shift, and thus offered an excellent model system for my study of the effects of grazing by cryptic herbivores on community composition and their potential restoration value. I had four major objectives: (1) determine the suitability of Maguimithrax spinosissimus for manipulating grazing intensity …

Sponge Community Biocomplexity, Competition, And Functional Significance In Hard-Bottom Habitats Of The Florida Keys, Fl (Usa), Marla Maxine Valentine

Biological Sciences Theses & Dissertations

Sponges can have powerful effects on ecosystem processes in shallow, tropical marine ecosystems and are an integral component of the bentho-pelagic cycle of nutrients, via filtering of dissolved and particulate organic matter from the water column. The diversity of marine communities is thought to play a determining role in intensity of ecosystem processes; thus the loss of taxa alters community function and by extension ecosystem processes. Coastal sponge populations worldwide are increasingly exposed to declining water quality that in several regions has resulted in mass sponge mortalities and reduced sponge diversity. In the Florida Keys (Florida, USA), for example, frequent …

The Importance Of Keeping The Big Ones: Harvest Slot Limits And Marine Protected Areas For The Management Of The Caribbean Spiny Lobster, Gayathiri Gnanalingam

Biological Sciences Theses & Dissertations

Fishing typically removes the oldest and/or largest individuals from populations undermining stability and reproductive success. Traditional fisheries management tools fail to protect these oldest and/or largest individuals, but two less conventional tools: marine protected areas (MPAs), and harvest slot limits have the potential to do so. Here I tested the possible use of these tools for the Caribbean spiny lobster, Panulirus argus, an iconic and economically valued species. After decades of intense fishing, the largest lobsters have largely been wiped out. The loss of the largest lobsters is significant as large lobsters have considerably greater reproductive potential than their …

Potential Interaction Analysis Of Offshore Wind Energy Areas And Breeding Avian Species On The Us Mid-Atlantic Coast, Jeri Lynn Wisman

Biological Sciences Theses & Dissertations

Due to increasing US interest in developing wind energy sites in offshore waters, we synthesized existing data on colonial breeding seabird populations with the potential risk of interacting with lease areas in the mid-Atlantic. Previous efforts by BOEM and NOAA have predicted avian density using at-sea survey data; we seek to complement this work by focusing specifically on birds during the critical and energetically demanding breeding life history stage. We combined colony size and location for each species along the mid-Atlantic coast with buffers around the colonies that correlate with the species’ foraging range. We integrated population size, vulnerability to …

Local Adaptation Signatures In Thermal Performance Of The Temperate Coral Astrangia Poculata, Hannah Elise Aichelman

Biological Sciences Theses & Dissertations

The Northern Star Coral (Astrangia poculata) is an understudied temperate scleractinian coral that provides unique opportunities to understand the roles of phenotypic plasticity and local adaptation in coral physiological tolerance limits. Astrangia poculata inhabits hard bottom ecosystems from the northwestern Atlantic to the Gulf of Mexico and withstands an annual temperature range up to 20°C. Additionally, A. poculata is facultatively symbiotic and co-occurs in both symbiotic (“brown”) and aposymbiotic (“white”) states. Here, brown and white A. poculata were collected from Virginia (VA) and Rhode Island (RI), USA and exposed to heat (18-32°C) and cold (18-6°C) temperature assays during …