Ecology and Evolutionary Biology Commons^™

Use Of Unoccupied Aerial Vehicle (Drones) Based Remote Sensing To Model Platform Topography And Identify Human-Made Earthen Barriers In Salt Marshes, Joshua J. Ward

Masters Theses

Elevation is a foundational driver of salt marsh morphology. Elevation governs inundation and hydrological patterns, vegetation distribution, and soil health. Anthropogenic impacts at grand scales (e.g., rising sea levels) and local scales (e.g., infrastructure) have altered the elevation of the salt marsh surface, changing the topography and morphology of these ecosystems. This study establishes and assesses means to document and analyze these impacts using Unoccupied Aerial Vehicle (UAV) based remote sensing to model platform topography. This thesis’s first and primary study presents and compares methods of producing high-resolution digital terrain models (DTMs) with UAV-based Digital Aerial Photogrammetry (DAP) and Light …

The Impacts Of Environment And Host Evolutionary Relationships On Lemur Microbiota, Rachel B. Burten

Doctoral Dissertations

Recent studies have shown that the mammal microbiome is modified by environmental conditions, and that reduced microbiome functionality is associated with host health issues. Microbiome data in wild and captive primate populations can therefore be used to assess their health as they encounter a variety of environments. Comparative studies of the microbiome can also inform disease ecology, conservation, and captive management strategies tailored to different primate species. Therefore, this study examines how the hair, oral, and gut microbiota of nine wild and captive lemur species are determined by host phylogenetic relationships and host environment. I found that host species identity …

The Wild Tomato Clade Offers Insights Into Fleshy Fruit Trait Evolution At The Phenotypic And Molecular Levels, Jacob R. Barnett

Doctoral Dissertations

Biologists have long been fascinated by the diversity of fleshy fruits, yet questions remain as to how this variety has evolved. According to the dispersal syndrome hypothesis, flowering plants improved their reproductive success by producing fleshy fruits with appealing combinations of traits that attract animal dispersers. However, animal preferences may not be the only selective pressure driving fruit trait diversity—conflicting forces include damage-inflicting seed predators and pathogens, abiotic habitat conditions, or constraints stemming from non-adaptive mechanical, developmental, or phylogenetic limitations. Few studies have examined the early stages of fleshy fruit evolution across an entire clade of recently diverged plant species. …

Incorporating Biodiversity-Ecosystem Function Relationships Into Models And Conservation Planning, Sarah R. Weiskopf

Doctoral Dissertations

Unsustainable use of nature and climate change are leading to unprecedented biodiversity declines. These declines have cascading impacts on ecosystem function and ecosystem services, and ultimately on human well-being. International agreements have been adopted that aim to address both crises. The Paris Agreement, adopted in 2015, set global emission reductions targets. In 2022, most countries agreed to the Kunming-Montreal Global Biodiversity Framework (GBF). The GBF sets 23 ambitious targets for 2030 ranging from reducing threats to biodiversity, meeting people’s needs through sustainable use and benefit sharing, and solutions for implementation. Although adopting global goals and targets is an important first …

The Discovery Of A Novel Bacteria From A Large Co-Assembly Of Metagenomes, Matthew Finkelberg

Masters Theses

In the summer of 2022, a co-assembly of metagenome was created using the microbes found at Barres Woods in Harvard Forest. 14 samples were taken, and sample was split into the organic and mineral layer, which totals 28 Bulk MAGs. Within this Co-assembly, 4 different genomes were found which were designated with the phylum of FCPU426. Three of which were considered medium quality and one being assigned high quality. The novel phyla first appeared in NCBI and GTDB databases in June 2018. The name FCPU426 dates to 2010 and was named based on the 16s amplicon sequencing.

The novel phylum …

Climate Change Attitudes Of United States Family Forest Owners And Their Influence On Forest Management Practices, Logan Miller

Masters Theses

Understanding family forest owners’ (FFOs’) attitudes and behaviors towards climate change will allow for more sustainable forest management practices to be implemented, helping to combat climate change and its impacts. The goals for this research are (1) to begin measuring U.S. FFO attitudes toward climate change, (2) to determine what factors impact these attitudes, and (3) to determine how they influence the FFO’s management practices using the Responsible Environmental Behavior (REB) framework (Hines et al. 1987). Chapter 1 explores the different facets of my thesis project focusing on forests and forests’ ecosystem services, forest ownership in the United States, and …

Factors Affecting The Distribution Of Malayan Sun Bear In Htamanthi Wildlife Sanctuary, Northern Myanmar, Min Hein Htike

Masters Theses

To understand the modeling challenges and to examine the important factors considered in Malayan sun bear (Helarctos malayanus) distribution studies, we reviewed 33 peer-reviewed articles published from 2003-2023. These studies used 54 environmental or anthropogenic variable types to investigate the distribution, habitat preference, and home range composition of sun bears. Most variable types are human disturbance (n=4), climate (n=3), topography (n=1), vegetation (n=11), or other ecological factors (n=3). Nevertheless, a number of rarely used variables might also be useful to include in future evaluations (i.e., food abundance), and observational evidence suggests that predator occurrence could also be informative. …

Timing Is Everything: Climate Change Implications For Phenological Events And Reproductive Success In River Herring, Meghna N. Marjadi

Doctoral Dissertations

Anadromous river herring (alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis)) make annual spring spawning migrations from the ocean to freshwater, where juveniles reside before emigrating to the ocean. Climate change may alter environmental and biological cues that prompt both adult migration and juvenile emigration, with implications for adult spawning success and offspring survival for these imperiled species. Shifts in adult migration have been observed in some rivers, while impacts on reproductive success and juvenile survival remain unknown. Cues for juvenile emigration are poorly understood as they have been explored at limited spatial and temporal scales. …

Population Ecology Of The Diamondback Terrapin At Their Northern Range Limit, Patricia M. Levasseur

Doctoral Dissertations

This dissertation research focuses on the population ecology of the northern diamondback terrapin (Malaclemys terrapin terrapin) in Wellfleet Bay, MA. The northern diamondback terrapin is a Massachusetts-threatened turtle species restricted to estuarine environments. With a range from Cape Hatteras, North Carolina to Massachusetts, Cape Cod Bay is the northernmost part of the subspecies range. Mass Audubon’s Wellfleet Bay Wildlife Sanctuary has been using capture-mark-recapture (CMR) methods since 1980 marking over 3,000 individuals; however, low detection rates and variable search effort have resulted in unreliable population estimates not suitable for informing conservation practices within the bay. Low sample sizes, …

Evaluation Of Acoustic Telemetry Array Performance And Fine- Scale And Broad-Scale Spatial Movement Patterns For Coral Reef Species In Culebra, Puerto Rico, Roxann Cormier

Masters Theses

Acoustic telemetry is an important tool when studying the spatial ecology of marine animals. First, it is important to identify the challenges of using this tool in shallow tropical marine environments before tracking marine animals. One significant issue that can influence the effectiveness of acoustic telemetry is the efficiency or detectability of acoustic signals by receivers. Understanding factors influencing detection efficiency of acoustic tags is especially important for fine-scale positioning systems (such as the VEMCO positioning system, VPS) that use detections in an overlapping receiver network to calculate geographic positions of tagged fish. I modelled the efficiency of an acoustic …

Habitat Use And Individual-Based Modeling Of Bald Eagles In Maine Near Current And Potential Wind Energy Facilities, Blake Massey

Doctoral Dissertations

Wind energy facilitates have expanded significantly in the United States over the last few decades due to technological advancements, regulatory incentives, and policies aimed at increasing renewable energy production, but poorly sited turbines may have adverse effects on local and migratory birds, bats, and other wildlife and their habitats. In the northeastern United States, Maine has become the leader in wind energy but also has the greatest density of Bald Eagles in the region. As wind energy production continues to be developed across the state and in coastal waters, research is needed to analyze and assess potential risks, including displacement, …

Chemosensory Receptors In Berghia Stephanieae: Bioinformatics And Localization, Kelsi L. Watkins

Masters Theses

Chemosensation is achieved through the binding of chemical signals to chemoreceptor proteins embedded in the membranes of sensory neurons. The molecular identity of these receptors, as well as the downstream processing of chemosensory signals, has been well studied in arthropods and vertebrates. However, very little is known about molluscan chemosensation. The identity of chemoreceptor proteins in the nudibranch mollusc Berghia stephanieae are unknown. Data from other protostome and molluscan studies suggest Berghia may use ionotropic receptors for some forms of chemoreception. This study used a bioinformatics approach to identify potential chemosensory ionotropic receptors in the transcriptome of Berghia. A …

Applications Of Statistical Physics To Ecology: Ising Models And Two-Cycle Coupled Oscillators, Vahini Reddy Nareddy

Doctoral Dissertations

Many ecological systems exhibit noisy period-2 oscillations and, when they are spatially extended, they undergo phase transition from synchrony to incoherence in the Ising universality class. Period-2 cycles have two possible phases of oscillations and can be represented as two states in the bistable systems. Understanding the dynamics of ecological systems by representing their oscillations as bistable states and developing dynamical models using the tools from statistical physics to predict their future states is the focus of this thesis. As the ecological oscillators with two-cycle behavior undergo phase transitions in the Ising universality class, many features of synchrony and equilibrium …

Flexible Phenotypes, Energetics, And Whole-Animal Performance Of Migratory Songbirds, Michael Griego

Doctoral Dissertations

Animal life has evolved innumerable strategies to adapt to a great range of environmental conditions present on earth. The physiology of free-living animals has thus been shaped to allow for maximal performance under challenging conditions and has given rise to traits that enable animals to overcome daunting ecological pressures. Few life history stages in the animal kingdom rival the intensity of annual avian migration: the extreme metabolic requirements of long-distance flight coupled with navigating vast and hostile ecological barriers results in enormously high mortality for young birds. It is therefore the main focus of this thesis to identify physiological traits …

Constraints Of The Imagination: How Phenotypes Are Shaped Through Genetics, The Environment, And Development, Michelle Gilbert

Doctoral Dissertations

Phenotypic constraints are ubiquitous throughout nature, being found throughout all stages of life and at multiple different biological levels including cellular, genetic, environmental, behavioral, evolutionary, and developmental. These constraints have shaped, not only the natural world, but the way that we perceive what is possible, or impossible, an observation made clear by François Jacob in his 1977 paper “Evolution and Tinkering”. This is reflected in the literature, repeatedly, by the regular occurrence of densely packed visualization of phenotypic space that seemingly always have large areas that go unoccupied. Despite constrained regions of space being observable across countless taxa, identifying the …

Ecology And Phytochemistry Of The Non-Native Plant Thlaspi Arvense (Brassicaceae) In Subalpine Meadows Of Colorado, Usa, Elsa Cousins

Doctoral Dissertations

Climate change is altering ecosystems at multiple scales. Globally, warming temperatures and increasing irregularity of precipitation will have large scale impacts on species distribution and success. Locally, understanding species response to fine scale microhabitat variation can provide key insights into population adaptation. Non-native plants represent an opportunity to investigate population level response and adaptation to relatively novel combinations of biotic and abiotic environments. Subalpine meadows are at the intersection of biotic and abiotic change, as large-scale climatic shifts alter water and temperature regimes and species range shifts become increasingly common and larger in scale. This dissertation addresses these questions of …

Songbird-Mediated Insect Pest Control In Low Intensity New England Agriculture, Samuel J. Mayne

Masters Theses

Global agricultural intensification has caused large-scale wildlife declines, but agricultural lands that maintain natural habitats can support healthy wildlife populations and receive significant ecosystem services from these natural communities. However, how on-farm biodiversity results in beneficial ecosystem services is highly variable and is reported to differ among taxa and guilds. One group that has attracted attention for their potential beneficial role in reducing pest abundance are birds. Understanding the role of bird communities and individual species in pest control could be important for managing farms under a low intensity agroecological framework. In New England, farmers are increasingly applying low intensity …

The Influence Of Climate Change On The Ecology Of The Arctic Ground Squirrel In Denali National Park, Ak., Nigel A. Golden

Doctoral Dissertations

This dissertation research focuses on the ecology of the Arctic ground squirrel (Urocitellus parryii) in Denali National Park and Preserve, AK. The Arctic ground squirrels is a species of interest for monitoring efforts under the National Park Services’ Vital Signs Monitoring Program under the Vital Signs Monitoring program. The focus of this program is to monitor what is considered to be the most significant indicators of ecological conditions of the specific park resources that are of the greatest concern. The CAKN designated the Arctic ground squirrel (Urocitellus parryii) as one indicator species of park ecosystems. Despite being easy to observe …

The Spatial Distribution Of Invasive Plant Presence, Abundance, And Impact, Evelyn M. Beaury

Doctoral Dissertations

Across the globe, native ecosystems are increasingly threatened by the spread and negative impacts of non-native, invasive plants. While many hypotheses explore what contributes to the damage caused by invasive species, few studies have tested these hypotheses at the macroscale. My dissertation addresses this knowledge gap by synthesizing thousands of vegetation surveys from ecosystems across the United States. I leverage existing, as well as explore new macroecological methods to deepen our understanding of the spatial ecology of plant invasions. My dissertation also asks how effective management and policy has been at reducing plant invasions. The primary introduction pathway for invasive …

Drivers And Direct Impacts Of Lean Mass Dynamics On The Stopover Ecology And Migratory Pace Of Nearctic-Neotropical Migrant Songbirds In Spring, Mariamar Gutierrez Ramirez

Doctoral Dissertations

Annual migration in songbirds is one of the most demanding life-history stages. It represents a period of high mortality, yet there is still much unknown about the ecological correlates that influence its successful completion. After long non-stop migratory flights, birds require a stopover period to rest and replenish depleted energy reserves. Birds use fat as the primary fuel to power long-distance flights. However, birds also burn lean tissue, which results in significant reductions in muscle and organ masses. The discovery and quantification of lean mass catabolism represented a paradigm shift in migration ecology because non-fat components were thought to remain …

Thermal Ecophysiology Of Juvenile Anadromous River Herring, Lian W. Guo

Doctoral Dissertations

Temperature controls the rate of all biochemical processes, and thus can significantly influence the physiology and ecology of all living organisms on earth. Understanding how temperature influences fitness can therefore provide insight into mechanisms affecting population size, dynamics, and geographic distributions, especially in the context of climate change. Early life stages of fishes experience significant selective pressure to grow large and accumulate energy reserves in order to avoid predation and starvation. Increasing temperatures will increase routine metabolic rates, which may result in less energy being available for growth and energy storage. In this thesis, I examine the effects of temperature, …

Developing A Restoration Strategy For Brook Floater (Alasmidonta Varicosa) In Massachusetts, Ayla Skorupa

Doctoral Dissertations

The brook floater (Alasmidonta varicosa) is a freshwater mussel (Order: Unionida) native to Atlantic Slope drainages from Canada (Nova Scotia and New Brunswick) to Georgia, U.S. The precipitous loss of brook floater populations and extant low densities in many regions evokes an urgency to establish conservation initiatives for the species. A targeted approach to population restoration is critical in Massachusetts (MA) where brook floater remain in low abundances in only 4 of the 11 originally occupied watersheds (Hydrologic unit code-12). A succinct strategy to restore a rare freshwater mussel species is unavailable yet critical to aid restoration. The …

The Effect Of Disturbance And Invasion On Fungal And Plant Communities Over An Elevational Gradient, Adam N. Trautwig

Doctoral Dissertations

High-elevation ecosystems are at risk of disruption from the future effects of climate change. Sub-alpine meadows are a source of unique plant populations, intraspecific variation of elevationally extreme populations, and vital sources of fresh water resources. We evaluated the whole fungal communities, arbuscular mycorrhizal fungal (AMF) communities, plant communities, and edaphic variables of sub-alpine meadows in undisturbed, disturbed, and disturbed with a non-native member of the Brassicaceae (Thlaspi arvense) plots. In conjunction with measuring the effects of disturbance on native communities we conducted potting experiments on a dominant grass of sub-alpine meadows (Festuca thurberi). We also …

Hydrologic Controls On Phosphorus Speciation And Mobilization In A Subalpine Watershed (East River, Colorado), Lucia Isobel Arthen-Long

Masters Theses

The cycling of phosphorus (P) through floodplain environments is critical to ecosystem productivity and has significant implications on both water quality and soil fertility. P export from soils in response to saturation has been well documented, but the relative vulnerability of specific P pools to mobilization remains poorly constrained, as do the mechanisms mediating its release. The prediction of P availability in and export from mountainous floodplain soils is of great importance as global climate change is projected to significantly alter precipitation regimes in alpine systems. This study combined a thorough characterization of P distribution across a hillslope to floodplain …

Statistical Improvements For Ecological Learning About Spatial Processes, Gaetan L. Dupont

Masters Theses

Ecological inquiry is rooted fundamentally in understanding population abundance, both to develop theory and improve conservation outcomes. Despite this importance, estimating abundance is difficult due to the imperfect detection of individuals in a sample population. Further, accounting for space can provide more biologically realistic inference, shifting the focus from abundance to density and encouraging the exploration of spatial processes. To address these challenges, Spatial Capture-Recapture (“SCR”) has emerged as the most prominent method for estimating density reliably. The SCR model is conceptually straightforward: it combines a spatial model of detection with a point process model of the spatial distribution of …

Data Access, Distribution Models, And Stable Isotopes: Merging Approaches To Improve Bear Distribution Estimates And Bear Carnivory For Conservation, Nereyda Falconi

Doctoral Dissertations

My dissertation aims to contribute to the knowledge of Andean bears in Peru. The Andean bear (Tremarctos ornatus) is the sole bear species in south America. The lack of knowledge on different aspects of Andean bear ecology, biogeography, and abundance patterns hinders current conservation efforts for the species. I compiled Andean bear occurrence records in Peru with collaboration from many colleagues and created an open-access database at the GBIF data repository. Next, I modeled the distribution of Andean bear within Peru and compared estimates including and excluding unpublished records. I found that models combining published and unpublished records …

On Spatiotemporal Connectivity Dynamics: Perspectives From A Naturally Fragmented Metapopulation, Joseph Drake

Doctoral Dissertations

Connectivity has quickly become a central tenet of ecological research, frequently evoked for conservation research and management activities. However, the concept of connectivity has proliferated into many forms for many different perspectives. Generally said, population distributions, demography, landscape, and dispersal all contribute to connectivity in a meaningful way. While great progress has been made in increasing realism in connectivity, one component seemed to stand out as being underappreciated: the role of population dynamics in the application of landscape connectivity. I began to acquire an appreciation for how common modeling approaches make assumptions about these core components of connectivity. In Chapter …

Monitoring Mammals At Multiple Scales: Case Studies From Carnivore Communities, Kadambari Devarajan

Doctoral Dissertations

Carnivores are distributed widely and threatened by habitat loss, poaching, climate change, and disease. They are considered integral to ecosystem function through their direct and indirect interactions with species at different trophic levels. Given the importance of carnivores, it is of high conservation priority to understand the processes driving carnivore assemblages in different systems. It is thus essential to determine the abiotic and biotic drivers of carnivore community composition at different spatial scales and address the following questions: (i) What factors influence carnivore community composition and diversity? (ii) How do the factors influencing carnivore communities vary across spatial and temporal …

Discovering Mechanisms Driving Adaptive Evolution In The Cross-Kingdom Fungal Pathogen Fusarium Oxysporum, Dilay Hazal Ayhan

Doctoral Dissertations

Fusarium oxysporum is a cross-kingdom pathogenic fungus that can cause vascular wilt disease in many economically important plants and local or disseminated infections in humans. Although it lacks a sexual stage in its life cycle, F. oxysporum can adapt to a wide range of hosts because of accessory chromosomes (ACs) which are enriched in host-specific genes and repeat content. This dissertation investigates the mechanisms that drive the adaptive evolution in the cross-kingdom pathogen F. oxysporum using comparative genomics and an experimental evolution approach. The first chapter compares phenotypes and genomes of a plant pathogenic isolate F. oxysporum f. sp. lycopersici …

Factors Influencing Primate Hair Microbiome Diversity, Catherine Kitrinos

Masters Theses

Primate hair is both a substrate upon which essential social interactions occur and an important host-pathogen interface. As commensal microbes provide important immune functions for their hosts, understanding the microbial diversity in primate hair could provide insight into primate immunity and disease transmission. While studies of human hair and skin microbiomes show differences in microbial communities across body regions, little is known about the nonhuman primate hair microbiome. In this study, we collected hair samples (n=159) from 8 body regions across 12 nonhuman primate species housed at 3 US institutions to examine 1) the diversity and composition of the primate …