Population Biology Commons^™

A Genetic Analysis Of The Rare Endemic Astragalus Ripleyi Barneby, Juan Antonio Jaramillo-Chico

Master's Theses

Astragalus ripleyi Barneby is a rare endemic species found in the San Luis Valley of the southern portions of the Rocky Mountains in Colorado and New Mexico. Though not federally listed as endangered, the species is on the Bureau of Land Management’s Sensitive Species List, warranting protection and continued management. This study aims to provide information about the genetic health of the species to inform conservation efforts and provide updated management recommendations. A genetic health analysis was conducted investigating the levels of diversity present in the species, how genetic diversity is structured across the known range of the species and …

Investigating Cryptic Diversity In The Hawaiian Endemic Plant, Psychotria Mariniana (Rubiaceae), Uyen Thi Hoang Nguyen

Master's Theses

Islands, with their isolation and steep environmental gradients, serve as natural laboratories for studying speciation. Molecular phylogenetic and population genetic methods utilizing Next-Generation Sequencing (NGS) have revolutionized our ability to document patterns of genetic divergence and diversity. Cryptic diversity, genetically distinct populations that were previously unrecognized as unique, and cryptic speciation, where divergent genetic populations may be deserving of status as unique species, have been observed in many taxa. The Hawaiian Islands provide an ideal setting for studying divergence and speciation due to their extreme isolation, known ages, and volcanic origin. Previous work has investigated the evolutionary relationships of the …

Quantifying Genetic Diversity In Nematode Feeding Rate, Jacob King

Honors Theses

Understanding how populations persist under changing environmental conditions is a central question in ecology and evolutionary biology. Variation in traits related to resource acquisition may play a key role in determining population survival when resources are limited or fluctuate over time. In this study, I investigated how variation in feeding-related traits influences population persistence using a combination of computational modeling and laboratory experiments. I developed a stochastic, individual-based consumer–resource model to simulate population dynamics across varying levels of trait variance and resource regimes. Across 60,000 simulated populations, increased trait variation consistently reduced extinction risk and extended persistence time, although the …

Alabama Prairie Reconstruction: Comparing Management Pathways For A Southeastern Landscape, Cecelia R. Geyer

Theses

Southeastern prairies are highly biodiverse yet increasingly threatened by land-use change, fire suppression, and habitat fragmentation. These disturbance-dependent systems rely on periodic fire and grazing to maintain plant diversity and ecosystem function. This study evaluates prairie restoration strategies by testing predictions from the Intermediate Disturbance Hypothesis and the Patch Mosaic Burn Hypothesis. The study site was divided into three treatments: prescribed burned only (B), prescribed burned with mowing (BM) to simulate grazing, and an undisturbed control (C). A standardized mix of native plant seeds was broadcast across all treatments. Ecosystem health and function were evaluated using plant community diversity and …

Decoupling Of Reproduction And Lifespan Trade-Off In Caenorhabditis Elegans Through Microbial Programming, Nora M. Villafuerte

LSU Master's Theses

The microbiome is increasingly recognized as a major regulator of host physiology. Using the Caenorhabditis elegans model, we investigated how natural commensal bacteria modulate host reproduction and lifespan through internal egg hatching, a phenotype in which retained embryos hatch within the maternal body. Screening strains from the CeMbio collection identified four focal strains Ochrobactrum BH3, Lelliottia JUb66, Pantoea BIGb0393, and Enterobacter CEent1 that significantly increased internal egg hatching during the late reproductive period. This contrasts with pathogenic bacteria, which induce early-onset internal egg hatching. Across the focal strains, worms exhibited reduced total brood size but an expanded reproductive window relative …

Using Camera-Based Unmarked Spatial Capture-Recapture Modeling To Estimate Reintroduced Elk (Cervus Canadensis) Population Parameters And Distribution In Southeastern Kentucky, Claire Marie Muia

Theses and Dissertations--Forestry and Natural Resources

Estimation of population parameters is important for wildlife management decisions. Elk reintroduced to southeastern Kentucky experienced early irruptive population growth and are currently monitored using a statewide harvest-based statistical population reconstruction model (SPR) across the Kentucky Elk Restoration Zone (KERZ). Because the SPR model is spatially coarse and difficult to scale to the smaller management units comprising the KERZ, we conducted a spatially explicit capture-recapture study using a clustered camera-trapping array deployed for 10 weeks from June–August 2024 to estimate elk population parameters within Management Unit 4. Due to a lack of resights of GPS-marked elk, population parameters were estimated …

An Ecological-Evolutionary Investigation Of Phenotypic, Genetic, And Environmental Variation And Correlations Among Reproductive Traits Of Tall Goldenrod (Solidago Altissima), Michael J. Wise, Daniel Lavy, David E. Carr, Warren G. Abrahamson Ii

Faculty Journal Articles

Although fitness-related traits are expected to be under strong selection, traits related to reproduction are often quite variable within plant populations. We used data from two large greenhouse experiments to quantify phenotypic, genetic, and environmental variation, as well as genetic tradeoffs that might help explain the maintenance of withinpopulation variation in four traits related to sexual or vegetative reproduction in tall goldenrod (Solidago altissima). The goldenrod population exhibited high levels of both phenotypic and genetic variation for capitulum (flower head) number and size, seed production, and rhizome growth. Significant negative genetic correlations were present between the number of capitula and …

Hybridization And Introgression In Marine Invertebrates: Population Genomics Of Phymactis Papillosa And Asterias Sea Stars, Christopher J. Dookie

Dissertations and Theses

Hybridization and introgression are evolutionary significant processes in marine invertebrates (Sanford & Kelly,2011) yet genome-wide investigations of gene flow in these taxa remain limited relative to vertebrate systems (Marchi et al., 2021). This thesis presents genomic analyses of hybridization and introgression in two marine invertebrates occupying contrasting oceanographic settings and characterized by contrasting genomic datasets: restriction-site associated DNA sequencing (RADseq) SNP data for the eastern Pacific sea anemone Phymactis papillosa and whole genome sequencing (WGS) data for the North Atlantic sea stars Asterias rubens and Asterias forbesi. For each system, I applied coalescent-based species tree inference using CASTER (Zhang …

A Review Of Mockingbird Song, Jacqueline Milander

Student Theses

The northern mockingbird (Mimus polyglottos) is known for its large repertoire and highly versatile song patterns.  It is a frequent mimic that is thought to continue learning sounds from its environment for the duration of its life.  Utilizing available song studies, this is a comprehensive review of northern mockingbird song, including learning, mimicry, repertoires, song dependence on seasonal cyclicity, and song function, particularly interspecific territoriality. While much discussion has surrounded the idea that northern mockingbirds engage in interspecific territoriality and that vocal mimicry functions in intersexual selection, this review provides new insight into the possibility that latitudinal differences among populations …

Using Side Looking Hydroacoustics And Community Size Spectra To Assess Invasive Carp’S Impact On Fish Assemblage Integrity, Daniel Jacob Bryan

Graduate Theses, Dissertations, and Problem Reports (ETD)

Often accounting for over half of total fish biomass, invasive silver carp have dramatically reshaped the ecosystem of the Mississippi River and its tributaries. These high silver carp densities have been shown to affect native fish body condition, abundance, and community structure, highlighting the need for efficient methods to quantify silver carp’s effect on the native fish assemblage. Community size spectra (CSS) is a metric that quantifies fish assemblage body size structure based on the decrease in fish abundance with increasing size. To estimate silver carp’s effects on CSS in the Ohio River, side looking hydroacoustic monitoring was used alongside …

Current Threat To The Native Endemic Muckalee Crayfish (Procambarus Gibbus) From An Invasive Crayfish (Faxonius Palmeri Creolanus) And Tests Of Cold Tolerance As A Limiting Factor, Alexandria L. Exum, Nickeya Wynn, William Ellerbee, Madaline Toth, Otto T. Lorenz

Georgia Journal of Science

Surveys for native and invasive crayfish were conducted in Muckalee creek in 2015 and 2021. Both surveys used passive minnow traps and examined upstream and downstream sites, including at the mouth of the creek where it connects with the Flint River. The Flint River has been overrun with an invasive crayfish species, Faxonius palmeri creolanus (Creole Painted Crayfish) and its range has spread rapidly throughout southwest Georgia. In Muckalee Creek there were only a few F. p. creolanus found during each survey and both times they were only found at the mouth of the creek. One hypothesis on why they …

The Ecology Of Arthropod Rain In A Tropical Forest., Andrew Robert Seiler

Electronic Theses and Dissertations

Tropical forests are structured by complex vertical linkages and nutrient exchanges between canopy and understory habitats. These linkages include the downward flux of organisms, the movement of canopy fauna, and the recycling of nutrients through litter and organic matter deposition. This dissertation investigates arthropod rain and its role in connecting the canopy and forest floor processes in a lowland tropical forest in Panama. Chapter 2 quantifies “arthropod rain”, the fall of canopy arthropods into the understory. Using pan and pole traps, I measured the composition, abundance, and biomass of arthropods falling from the canopy and assessed environmental drivers of the …

Understanding The Spread Of Black Sigatoka Disease: A Deterministic And Stochastic Modeling Approach, Bernard Asamoah Afful, Luis F. Gordillo

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Drivers And Consequences Of Changes In Nectar Microbiome Composition Across Spatial And Biological Scales, Daniel A. Barker

Electronic Theses and Dissertations

Microbial communities inhabiting floral nectar, known as the nectar microbiome, are important mediators of plant-pollinator interactions. However, the ecological and environmental factors that shape the composition of these microbial communities remain poorly understood. While previous studies have examined the effects of a few microbial groups, typically independent of one another, on one plant or pollinator species, this dissertation takes a wide-scale approach to explore how abiotic conditions and biotic interaction’s structure microbial communities within floral nectar. Furthermore, I also quantify how variation in microbial richness and identity influences pollinator behavior and plant reproductive success.

This dissertation shows that microbial abundance …

Pollinator Plant Communities Within Restored Montane Longleaf Pine Ecosystems, Hanen Van Rossem

Master's Theses

Historically the fire-dependent and biodiverse longleaf pine (Pinus palustris) ecosystem was the dominant ecosystem of the Southeastern US. This ecosystem’s range was massively reduced due to land conversion and fire exclusion, causing the decline of many native species. Efforts to restore and protect longleaf pine stands are now ongoing with the goal of expanding habitat and refuge for threatened species. Differences in restoration practices and prior land use may influence the extent to which restored habitat patches can support pollinators and their plants. This study compared pollinator plant biodiversity between restored neighboring montane longleaf pine stands that differed in …

Balancing Burrowing Owl (Athene Cunicularia Hypugaea) Protections While Maintaining Renewable Energy Development Within The San Joaquin Valley, Madison Lenzi Mcginn

Master's Projects and Capstones

Balancing the needs of wildlife and people has long been a complex challenge. The San Joaquin Valley exemplifies this tension, as space for agriculture and urbanization compete for land use of native grasslands– often resulting in the conversion of grasslands for agriculture fields, commercialized areas, or energy development. With an increasing number of agricultural landscapes going fallow and the passing of SB-100 in 2018, solar farm development has emerged as an attractive option to offset financial losses from unproductive farmland. However, the same landscapes favored for solar development also provide suitable habitat for sensitive species such the western burrowing owl …

New Mexico Cooper's Hawk Demographic Study: 2024 Annual Report, Brian A. Millsap Dr.

New Mexico Cooper’s Hawk: Publications

The 2024 Annual Report for a long-term (2011 -  present) demographic study of Cooper's hawks (Astur cooperii) in Albuquerque, New Mexico.

A Genetic And Spatial Analysis Of The Last Megafaunal Species (Tapirus Terrestris) In The Paraguayan Dry Chaco Forest, Emily Bowers

LSU New Orleans Theses and Dissertations

No abstract provided.

We Found Love In A Wetter Climate: The Impact Of Varying Climatic Conditions On The Prevalence Of A Fungal Endophyte In Elymus Virginicus Populations, Audrey Yung

Scripps Senior Theses

Epichloë is a genus of endophytes– symbiotic fungi residing within a plant’s tissue– that can provide mutualistic benefits to its host. The stress gradient hypothesis predicts that mutualism between species becomes stronger in conditions of high abiotic stress. We tested this idea by assessing how Epichloë prevalence in Elymus virginicus populations is affected by varying climatic conditions. We established plots of E. virginicus with known endophyte frequencies in the spring of 2023 at five sites across a precipitation gradient in Texas and Louisiana. We collected E. virginicus recruits in June and July 2024 at all field sites. To determine recruits’ …

Exploring The Reproductive Phenology Of Feral Horses In North America, Mattie Budine

Undergraduate Theses, Professional Papers, and Capstone Artifacts

Feral horses (Equus ferus caballus) are a prolific species in western North America. Due to their life history traits and history of domestication, they have a longer foaling period compared to native ungulates, such as elk (Cervus canadensis) and mule deer (Odocoileus hemionus). I examined the observed foaling seasons of different regional herds throughout North America to identify if foaling seasons are uniform across latitudes or if they present a latitudinal shift similar to ungulates. My dataset (n=523 foals) consisted of various research studies and unpublished observations of different feral horse herds throughout North America. The results are graphs comparing …

Assessing The Effects Of Wildfire Season Pm2.5 Exposure And Environmental Variables On Breeding Season Avian Body Condition, Cira Seyer-Ochi

Scripps Senior Theses

The increasing frequency and intensity of wildfires pose growing threats to wildlife, yet the indirect effects of wildfire smoke on avian populations remain largely unstudied. This exploratory study provides an initial assessment of how particulate matter 2.5 (PM2.5) associated with smoke pollution from the 2017 California wildfire season, in conjunction with precipitation and habitat type, influences the body condition of four resident bird species during the 2018 breeding season. Using bird banding data from 29 Monitoring Avian Productivity and Survivorship (MAPS) stations, I assessed the potential interactions between PM2.5 concentrations, precipitation, and habitat type with body condition for Song Sparrows …

Distribution And Ecology Of The Cedar Keys Mole Skink (Plestiodon Egregius Insularis), Kevin M. Enge, Louis A. Somma, Paul E. Moler, Travis M. Thomas, Matthew T. Fedler, John M. Matter, Dennis C. Haney

Papers in Herpetology

We conducted surveys for the Cedar Keys Mole Skink, Plestiodon egregius insularis (Mount), during 1989– 1999 and 2015–2024, examined museum vouchers, and compiled personal observations from others to determine the status and distribution of this subspecies, which has the smallest geographic distribution of the five subspecies and is being considered for federal listing. We observed Cedar Keys Mole Skinks on Airstrip Island, Atsena Otie, Cedar Point, Deer Island, North Key, Scale Key, Seahorse Key, Snake Key, and possibly Dog Island. We have anecdotal reports of Mole Skinks on Way Key, which contains the most potential habitat and is the main …

Exploring Coastal Plain Fish Ecology Across A Range Of Early-Life-History Traits And River Types, Bridgette Nicolosi

College of Graduate Studies: Theses & Dissertations

The ecological complexity of southeastern Coastal Plain rivers is reflected in the diversity of fish communities they support, yet the processes structuring early life dynamics remain poorly understood. This thesis explores the influence of environmental gradients on larval fish assemblage composition and American Shad (Alosa sapidissima) spawning phenology across two Georgia Coastal Plain river systems.

In the unregulated Ogeechee River, I investigated spatial and temporal variation in larval fish communities by comparing mainstem and tributary habitats to understand the role of tributaries in watershed-wide larval production. Larvae were collected biweekly from May to September 2024 at eight paired mainstem-tributary sites …

Bioindicators Of Mercury In Riverine Systems, Kathryn Mudica

All-Inclusive List of Electronic Theses and Dissertations

This study focuses on the bioaccumulation and biomagnification of mercury in freshwater food webs, with emphasis on bioindicators, such as macroinvertebrates, crayfish, and river otters. Despite regulatory efforts and advancements in monitoring, significant gaps remain in understanding mercury dynamics in freshwater systems—especially regarding its transport, methylation, and bioavailability across different ecosystems. To address these knowledge gaps, this study adopts a biocentric approach, emphasizing the role of living organisms in their environment. By utilizing macroinvertebrates, crayfish, and river otters as bioindicators, we aim to assess mercury bioavailability and distribution. These organisms provide varying temporal and spatial scales of mercury accumulation, offering …

Analyzing Head Morphology Trends With Increasing Population Density In A Jamaican Lizard Species, Lillian Durand

2024 Fall Honors Capstone Projects - Archive

Anolis lizards are model organisms for studying natural selection and evolutionary processes. One trait that is hypothesized to be advantageous for males is head size, as larger heads lead to stronger bite forces and increased likelihood in outcompeting other males for mates. To better understand how linked head size and intraspecific competition are, the head morphology of male A. lineatopus was analyzed among Jamaican populations with varying levels of population density. Population densities were determined using standardized plot surveys and mark resight models. Head dimensions and body condition for individual lizards were measured at each site. My study found that …

Insights Into Past Extreme Environments Through Ancient Biomolecules, Ioana Nicoleta Meleg, Magdalena Năpăruş-Aljancic, Yuichi Naito, Hervé Bocherens, Axel Barlow

FRONTIERS UNBOUND: Exploring Extreme Environments

No abstract provided.

The Influence Of Environmental Change On Genetic Diversity Across Spatial And Taxonomic Scales, Connor M. French

Dissertations, Theses, and Capstone Projects

The spatial distribution of genetic diversity is of interest to biodiversity scientists and conservationists and is a fundamental metric of biodiversity. Genetic diversity patterns across spatial and taxonomic scales contain information about population and assemblage dynamics that can convey their resilience to environmental change. Ectotherms are especially linked to their environments and may be especially sensitive to fluctuations in the environment over time. Herein, I investigate global and regional patterns of genetic diversity in two groups of ectotherms, insects and lizards, to understand the relationship between environmental change and genetic diversity, from populations to assemblages. Overall, my research aims to …

The Role Of Sexual Network Core Groups In Disease Epidemics, Jason Janeaux

LSU Doctoral Dissertations

Sexually transmitted infections (STIs) remain an economic and social burden, non-discriminately affecting sexually active individuals worldwide. The unique transmission of STIs is dependent upon host and pathogen life histories, as well as the underlying network structure of the host population. Within a population there is a group of individuals, the core group, that maintains STI presence and helps sustain ongoing transmission both within the core group and in the surrounding population. While the presence of these core groups is well documented, the criteria for inclusion into a sexual core group is not. In this dissertation, I explore common factors that …

High Intraspecific Diversity Of Pocillopora Damicornis In Southeast Asia Reflects Adaptive Potential To Climate Change, Maria Lucille Carr

Theses and Dissertations

Marine heatwaves are increasing in intensity and frequency because of increased emissions of greenhouse gases. On coral reefs, warmer temperatures cause coral bleaching, mortality, and shifts in benthic composition. However, coral bleaching responses and survival vary geographically. Several hypotheses may explain such geographical differences in thermal tolerance, including the possibility that some localities may support higher intraspecific diversity than other localities, increasing the likelihood of survival of some individuals through heatwaves. Here we assessed geographic patterns of intraspecific genetic diversity in the ubiquitous coral Pocillopora damicornis. Intraspecific genetic diversity was assessed for 428 sequences across 44 sites in the Pacific …

Trophic Ecology Of Black Swallowers (Scombriformes: Chiasmodontidae: Chiasmodon) In The Deep-Pelagic Gulf Of Mexico, Travis J. Kirk

All HCAS Student Capstones, Theses, and Dissertations

The ecology of deep-pelagic predatory fishes remains poorly understood despite their importance as ecosystem regulators and energy transfer vectors. This study investigated the trophic ecology of three species of the predatory fish genus Chiasmodon (“black swallowers”) in the Gulf of Mexico, a region that serves as an analog for the global low-latitude deep pelagial, the world’s largest cumulative ecosystem. Foraging habits (e.g., selectivity, chronology, daily ration) of an “advanced” evolutionary fish in a system that is otherwise dominated by basal fish taxa, were quantitatively estimated via high-resolution stomach content analysis. A quantitative dataset of both predator and prey abundance, the …