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Doctoral Dissertations

2020

Articles 1 - 16 of 16

Full-Text Articles in Ecology and Evolutionary Biology

Don't Delay: The Effects Of Tide Gates And Road-Stream Crossing Culverts On River Herring (Alosa Spp.) Spawning Migrations, Derrick J. Alcott Dec 2020

Don't Delay: The Effects Of Tide Gates And Road-Stream Crossing Culverts On River Herring (Alosa Spp.) Spawning Migrations, Derrick J. Alcott

Doctoral Dissertations

River herring (Alosa spp.) are anadromous fish that spawn in freshwater rivers and lakes in North America from Florida to Nova Scotia, CA. They have been listed as a species of conservation concern due to dramatic stock declines observed in the 1970’s. Stocks have failed to show significant signs of recovery despite over a decade of harvest restrictions throughout their range. Bycatch in commercial fisheries and reduced access to spawning habitat due to anthropogenic barriers to migration, such as dams and tide gates, have been identified as major causes of the decline in herring populations. Physical barriers to …

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Improving Understanding Of Forest Communities And Biodiversity With Multi-Dimensional Landscape Gradients, Ben J. Padilla Dec 2020

Improving Understanding Of Forest Communities And Biodiversity With Multi-Dimensional Landscape Gradients, Ben J. Padilla

Doctoral Dissertations

This dissertation was motivated by a desire to understand the effects of habitat degradation and urbanization on a single species in a single study system in western Massachusetts, the red-backed salamander (Plethodon cinereus), but along the way unexpected conceptual and methodological hurdles caused the work to grow into a multi-species, multi-region, and multi-scale endeavor. As I designed my dissertation research and began considering approaches to quantifying heterogeneity and human influence in my study landscape, I recognized inconsistencies in methods used to define and quantify landscape metrics, particularly in urban systems. To investigate further, I conducted a critical review …

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Prevalence Of Rats And Rodent Borne Pathogens Across Post-Katrina New Orleans, Bruno Marco Ghersi Dec 2020

Prevalence Of Rats And Rodent Borne Pathogens Across Post-Katrina New Orleans, Bruno Marco Ghersi

Doctoral Dissertations

Disasters are happening at an increasingly higher rate and intensity a trend that is expected to continue as more humans migrate to coastal urban areas. Disasters, and as importantly, disaster recovery can affect how native and pest populations will recover. My aim was to improve understanding of disease risk by evaluating the socioecological conditions that have shaped commensal rat recovery and distribution, as well as the pathogens they carry, across New Orleans after Hurricane Katrina. I first estimated relative abundance and distribution of commensal rats from rodent trapping conducted between mid-2014 and early-2017 across 96 sites in 10 areas of …

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Root Stage Distributions And Their Importance In Plant-Soil Feedback Models, Tyler Poppenwimer Dec 2020

Root Stage Distributions And Their Importance In Plant-Soil Feedback Models, Tyler Poppenwimer

Doctoral Dissertations

Roots are fundamental to PSFs, being a key mediator of these feedbacks by interacting with and affecting the soil environment and soil microbial communities. However, most PSF models aggregate roots into a homogeneous component or only implicitly simulate roots via functions. Roots are not homogeneous and root traits (nutrient and water uptake, turnover rate, respiration rate, mycorrhizal colonization, etc.) vary with age, branch order, and diameter. Trait differences among a plant’s roots lead to variation in root function and roots can be disaggregated according to their function. The impact on plant growth and resource cycling of changes in the distribution …

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A High Resolution Study Of Long-Term Vertebrate Decomposition In Human And Animal Model Systems, Lois S. Taylor Dec 2020

A High Resolution Study Of Long-Term Vertebrate Decomposition In Human And Animal Model Systems, Lois S. Taylor

Doctoral Dissertations

The effects of vertebrate decomposition are wide-ranging across multiple foodwebs, and have been shown to persist in the environment, however there is a lack of systematic assessment of these changes over long periods of time or in sufficiently high resolution as to resolve seasonal flux patterns. The ultimate aim of this body of research was to explore nematode systematics in decomposition environments, culminating in a pair of long-term human decomposition seasonal trials, in high resolution, with the specific intent of integrating the fields of soil chemistry, microbial ecology, and nematology in order to assess the relationships of cross-disciplinary impacts. Of …

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Root Phosphomonoesterase As A Vital Component Of Increasing Phosphorus Availability In Tropical Forests, Kristine Grace Manno Cabugao Dec 2020

Root Phosphomonoesterase As A Vital Component Of Increasing Phosphorus Availability In Tropical Forests, Kristine Grace Manno Cabugao

Doctoral Dissertations

Tropical forests, relative to other terrestrial ecosystems, exchange the largest amount of carbon with the atmosphere and also constitute a significant carbon sink. However, nutrient limitation, particularly of phosphorus (P), could limit growth of tropical forests and their function with the global carbon cycle. Thus, understanding root mechanisms to acquire P is necessary to representing the P cycle and corresponding interactions with plant growth. A large portion of total soil P in tropical forests occurs in organic forms, only accessible through root and microbial production of phosphatase enzymes. These phosphatase enzymes mineralize organic P into orthophosphate, the form of P …

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Costs Of Protected Areas In The United States, Diane Lebouille Dec 2020

Costs Of Protected Areas In The United States, Diane Lebouille

Doctoral Dissertations

Protected areas, or land owned in fee by agencies and non-profits to further conservation goals, have traditionally been the go-to choice for conservation interests. The UN Environment World Conservation Monitoring Centre estimates that, currently, close to 15% of all terrestrial and inland water areas are protected. This figure falls short of the Aichi Biodiversity Target of 17% in 2020, that was added to the Convention on Biological Diversity by its 196 signatories in 2010. But as the Convention prepares to set new post-2020 targets, this percentage is expected to keep increasing. Although acquiring a parcel of land is only one …

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Fear, Parental Behavior, And Community Structure In Residential Lands, Aaron M. Grade Sep 2020

Fear, Parental Behavior, And Community Structure In Residential Lands, Aaron M. Grade

Doctoral Dissertations

In an urbanizing world, residential lands present an opportunity for conservation of biodiversity right in our backyards. Informed conservation necessitates a mechanistic understanding of how development influences animal populations and communities. Birds nesting in residential lands are less productive in urban yards than rural yards. Urban yards also have higher densities of potential predators, but lower per capita predation, indicating that direct predation is not entirely responsible for lack of productivity. I suggest that fear effects, also known as non-lethal effects, could be a mechanism by which predators exert indirect influence on bird parental behavior and nestling condition in urban …

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Connecting The Social And Spatial Behaviors Of A Territorial Species (Anolis Carolinensis), Jordan M. Bush Aug 2020

Connecting The Social And Spatial Behaviors Of A Territorial Species (Anolis Carolinensis), Jordan M. Bush

Doctoral Dissertations

Why animals live where they do is a key question in ecology and evolution. An individual’s home range determines the resources they have access to, conspecifics they encounter, and predators and pitfalls they must avoid. Home range behaviors also have an inherently social component; where animals live affects the rivals they compete with and the mates they have access to. This is especially true in territorial species, as defensive displays make up a large portion of their social behaviors. In this dissertation, I sought to understand how territorial behaviors affect the social lives of the green anole lizard (Anolis …

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Incorporating The “Invisibles” In Ant Seed Dispersal: Microbial Mortality Agents In Myrmecochory, Chloe L. Lash Aug 2020

Incorporating The “Invisibles” In Ant Seed Dispersal: Microbial Mortality Agents In Myrmecochory, Chloe L. Lash

Doctoral Dissertations

Ant-mediated seed dispersal, myrmecochory, is a diffuse mutualism in which ants are rewarded for seed dispersal services with food via a seed-coat derived appendage, the elaiosome. Seeds gain dispersal benefits including escape from distance- and density- dependent mortality agents, protection from seed predators, and a nutrient-rich germination site in or near ant nests. However, microbes, have been essentially overlooked in this mutualism, despite their pathogenicity to the ants and plants involved. The work presented here investigates the effects of microbial mortality agents on the risks and benefits offered to ant and plant partners in myrmecochory. First, I investigate the effects …

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Interacting Effects Of Climate And Biotic Factors On Mesocarnivore Distribution And Snowshoe Hare Demography Along The Boreal-Temperate Ecotone, Alexej P. Siren Jul 2020

Interacting Effects Of Climate And Biotic Factors On Mesocarnivore Distribution And Snowshoe Hare Demography Along The Boreal-Temperate Ecotone, Alexej P. Siren

Doctoral Dissertations

The motivation of my dissertation research was to understand the influence of climate and biotic factors on range limits with a focus on winter-adapted species, including the Canada lynx (Lynx canadensis), American marten (Martes americana), and snowshoe hare (Lepus americanus). I investigated range dynamics along the boreal-temperate ecotone of the northeastern US. Through an integrative literature review, I developed a theoretical framework building from existing thinking on range limits and ecological theory. I used this theory for my second chapter to evaluate direct and indirect causes of carnivore range limits in the northeastern US, …

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How Do Adult Songbirds Learn New Sounds? Using Neuromodulators To Probe The Function Of The Auditory Association Cortex, Matheus Macedo-Lima Jul 2020

How Do Adult Songbirds Learn New Sounds? Using Neuromodulators To Probe The Function Of The Auditory Association Cortex, Matheus Macedo-Lima

Doctoral Dissertations

The ability to associate sounds and outcomes is vital in the life history of many species. Animals constantly assess the soundscape for cues associated with threats, competitors, allies, mates or prey, and experience is crucial for those associations. For vocal learning species such as humans and songbirds, learning sounds (i.e. perception and association learning) is also the first step in the process of vocal learning. Auditory learning is thought to depend on high-order cortical brain structures, where sounds and meaning are bound. In songbirds, the caudomedial nidopallium (NCM) is part of the auditory association cortex and is known to be …

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From Genes To Ecosystems: Resource Availability And Dna Methylation Drive The Diversity And Abundance Of Restriction Modification Systems In Prokaryotes, Spiridon E. Papoulis Jun 2020

From Genes To Ecosystems: Resource Availability And Dna Methylation Drive The Diversity And Abundance Of Restriction Modification Systems In Prokaryotes, Spiridon E. Papoulis

Doctoral Dissertations

Together, prokaryotic hosts and their viruses numerically dominate the planet and are engaged in an eternal struggle of hosts evading viral predation and viruses overcoming defensive mechanisms employed by their hosts. Prokaryotic hosts have been found to carry several viral defense systems in recent years with Restriction Modification systems (RMs) were the first discovered in the 1950s. While we have biochemically elucidated many of these systems in the last 70 years, we still struggle to understand what drives their gain and loss in prokaryotic genomes. In this work, we take a computational approach to understand the underlying evolutionary drivers of …

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Investigating The Effects Of Winter Drawdowns On The Ecological Character Of Littoral Zones In Massachusetts Lakes, Jason R. Carmignani Mar 2020

Investigating The Effects Of Winter Drawdowns On The Ecological Character Of Littoral Zones In Massachusetts Lakes, Jason R. Carmignani

Doctoral Dissertations

Anthropogenic alteration of water levels in lakes is a major stressor to the ecological integrity of littoral zones, which provide critical heterogenous resources that support diverse biological communities. Annual winter drawdowns have been practiced in Massachusetts (MA) for several decades; however, few studies have estimated impacts to littoral zone habitat and biological communities, particularly at relatively mild magnitudes (i.e., m) and in lakes that co-occur with other anthropogenic pressures (e.g., lakeshore development) as seen in MA lakes. My dissertation reviewed the winter drawdown literature and collected empirical data in MA lakes to characterize winter drawdown hydrological regimes and estimate responses …

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De-Coding The Impact Of Evolved Changes In Gene Expression And Cellular Phenotype On Primate Evolution, Trisha Zintel Feb 2020

De-Coding The Impact Of Evolved Changes In Gene Expression And Cellular Phenotype On Primate Evolution, Trisha Zintel

Doctoral Dissertations

The goal of the dissertation work outlined here was to investigate the influence of proximal processes contributing to evolutionary differences in phenotypes among primate species. There are numerous previous comparative analyses of gene expression between primate brain regions. However, primate brain tissue samples are relatively rare, and my results have contributed to the pre-existing data on more well-studied primates (i.e. humans, chimpanzees, macaques, marmosets) as well as produced information on more rarely-studied primates (i.e. patas monkey, siamang, spider monkey). Additionally, the primary visual cortex has not previously been as extensively studied at the level of gene expression as other brain …

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Neogene History Of The Kuroshio Current Extension And Planktic Foraminifera Evolutionary Implications, Adriane Lam Feb 2020

Neogene History Of The Kuroshio Current Extension And Planktic Foraminifera Evolutionary Implications, Adriane Lam

Doctoral Dissertations

There are outstanding questions as to how important currents are to dispersal, especially for the evolution of planktic foraminifera. During the Neogene Period there were significant increases in the diversity of planktic foraminifera that occurred during major tectonic gateway closures, episodes of warming and cooling, and reorganization and development of ocean gyres and currents. Relatedly, the behavior of some currents, namely western boundary currents, remains unknown through these times of global tectonic and climate events. This dissertation addresses outstanding questions related to how the Kuroshio Current Extension, the western boundary current of the northwest Pacific, responded to major tectonic and …

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