Ecology and Evolutionary Biology Commons^™

The Concept 'Pollination' And Bee Pan-Trap Color And Uv Reflectance Determine The Taxonomic Compositions Of Bee Taxa Captures Across An Elevation Gradient And Seasons In The Jemez Mountains Of New Mexico, Esther A. Burton, Kelly B. Miller, Paul J. Watson, David C. Witherington, Steven Poe, David Lightfoot

Biology ETDs

This thesis examines the pollinator concept and tests how sampling methods shape bee communities. Chapter 1 provides a conceptual and philosophical analysis, arguing that pollination is a process and that pollinators are context-dependent functional roles rather than fixed taxonomic categories. It traces the concept’s development from natural history to ecological theory, introduces a dual-goal model separating plant reproduction from visitor foraging, and proposes a classification framework based on evidentiary certainty and pollination potential to resolve ambiguity in pollination research.

Chapter 2 applies these ideas empirically by evaluating how pan-trap color and ultraviolet (UV) reflectance influence bee assemblages across elevation and …

Reassembling Riparian Ecosystems: Stream Restoration Effects On Vegetation, Arthropods, And Aquatic-Terrestrial Connectivity, Katelyn P. Driscoll

Biology ETDs

Riparian areas exist at the aquatic-terrestrial interface and provide disproportionate ecosystem services, yet multiple stressors have degraded these zones globally. Stream restoration seeks to reverse degradation, but rigorous evaluation of treatment effectiveness remains limited. I conducted a before-after-control-impact (BACI) study in the southern Rocky Mountains to evaluate two stream restoration treatments—beaver dam analogs (BDAs) and plug-and-ponds (P&Ps)—across three dimensions of riparian ecosystem response. Using Bayesian analysis, I quantified treatment effects on functional diversity and composition of riparian plant communities. Using generalized linear mixed models, I evaluated restoration effects on riparian arthropod abundance, richness and guild composition across lateral gradients and …

Efficacy Of Oil And Gas Production Site Remediation In U.S. Arid/Semi-Arid Regions, Skye Ontiveros

Architecture and Planning ETDs

Oil and gas production (OGP) is expanding, paralleled by its polluting leaks and spills (LS), and outpaced by its waste. This raises the question: Does remediation of LS occur effectively when needed to protect the environment and public, particularly in major producing regions like arid/semi-arid regions (ASAR), which account for approximately 72% of US oil and 42% of gas production? To answer, a review of the eight largest national remedial laws, sourced from the Code of Federal Regulations (CFR), identified 14 OGP exemptions for remedial determinants (RDs): factors affecting remedial frequency and efficacy (e.g. LS monitoring and chemical disclosure). An …

Assessing The Ecological Drivers And Consequences Of Partial Migration In Hudson River Striped Bass Over Three Decades, Caitlin Egan Zimmer

Biology ETDs

Climate change and shifts in human land use have caused extensive impacts to the connectivity, structure, and resilience of aquatic populations. Partial migration (PM), where only some individuals from a population migrate while the rest remain resident, can mitigate population-level responses to environmental stressors. However, little is known of the underlying mechanisms promoting variation in migration and whether these shift over time. In the Hudson River Estuary, striped bass (Morone saxatilis) are known to exhibit anadromous PM behavior. Here, I measured carbon isotopes (δ¹³C) of essential amino acids in striped bass scales to determine variation in …

The Island Biogeography Of Mangrove-Dwelling Vertebrates: Isolation, Specialisation, And Extinction, Jian Xiong David Tan

Biology ETDs

Mangroves are highly dynamic ecosystems that are widely distributed across the coastlines of the tropics and subtropics. Despite their low plant diversity, mangroves host a disproportionately high number of terrestrial vertebrate taxa. However, mangrove specialists — taxa that only occur in mangrove habitats — exhibit a global distribution that is incongruous with the broader background distribution patterns of mangrove-associated fauna, exhibiting higher diversity in Australia and Southeast Asia. This dissertation therefore aims to assess how the diversity and distribution of mangrove specialist fauna may have been shaped by the historical biogeography of mangroves, and the effects of mangrove specialisation on …

Plant Reproductive Strategies Shift In Response To Restoration Using Beaver Dam Analogs, Laurel F. Martinez

Biology ETDs

As riparian communities become increasingly degraded, restoration treatments are being implemented in streams to recover ecosystem functions. In the Jemez Mountains, beaver dam analogs (BDAs) are used to restore degraded streams by connecting the floodplain and increasing the extent of anoxic soil conditions. These environmental disturbances are expected to alter how riparian plants recruit, particularly their allocation to seed-based and vegetative regeneration strategies. We investigated whether BDAs and associated changes in soil water filled pore space (WFPS) affected riparian plant recruitment. We investigated the number of flowering stems as a proxy for seed-based regeneration and rhizome length and mass as …

Using Triple Oxygen Isotopes To Investigate Water Usage In Desert Ecosystems, Cloe V. Knutson

Earth and Planetary Sciences ETDs

In arid environments, maintaining water balance can be more critical for survival than obtaining food. As droughts intensify, understanding how animals manage body water is essential. Triple oxygen isotope analysis provides a novel way to trace water sources in animals, distinguishing contributions from free water, food-derived oxygen, and atmospheric O₂. We developed an equilibration method using CO₂–H₂O oxygen exchange and measured δ^’18O and Δ^’17O values via tunable infrared laser direct spectroscopy (TILDAS). Validated against traditional fluorination methods, this technique enables streamlined analysis of whole blood and plant samples. Applied to …

Nitrogen Addition Additively Boosts Climate-Driven Salsola Tragus (Russian Thistle) Invasion Into Southwestern Usa Grasslands, Melissa A. Bacigalupa

Biology ETDs

Effective management of invasive, non-native plants requires understanding key drivers of invasion, including nitrogen enrichment from atmospheric deposition and agriculture. Long-term studies are essential for capturing complex invasion dynamics yet remain uncommon. We used 22 years of observations and 14 years of nitrogen experiments to examine invasion by Salsola tragus (Russian thistle) into three semi-arid grasslands of central New Mexico. Invasion patterns varied, with rapid expansion in Chihuahuan Desert grassland and the Desert-Plains ecotone but stability in Plains grassland. Under ambient nitrogen, precipitation most strongly correlated with Russian thistle biomass and high native grass biomass was associated with Russian thistle …

Life After Death: Investigating The Resistance And Recovery Of Fungal Communities To Foundation Tree Mortality, Jessie F. Marlenee

Biology ETDs

Tree mortality can have cascading effects on the composition and resilience of interacting fungal communities. Yet, little is known about the impact tree mortality, distinct from abiotic drivers (i.e., drought), has on these communities. This dissertation focuses on the resilience of fungal communities to experimental tree mortality in a piñon-juniper woodland. In chapter one, I found that piñon mortality reduced piñon fine root biomass and piñon mycorrhizal fungal diversity, whereas juniper mycorrhizal fungi were unaffected by juniper mortality. In chapter two, I revealed that piñon mortality altered the composition and spatial structure of mycorrhizal and saprotrophic fungi in the soil, …

Human Impacts On Mammal Diversity From The Pleistocene To The Present, Carson P. Hedberg

Biology ETDs

Humans have fundamentally altered the planet’s biodiversity. It is critical to characterize these changes, but also to understand how they impact the structure and function of modern ecosystems. This dissertation investigates how anthropogenically mediated species losses and/or introductions influence ecological function and community structure in mammals across multiple temporal and spatial scales. We found that selective loss of large-bodied mammals over the Late Quaternary has led to severe losses in functional diversity in modern ecosystems, suggesting megafaunal mammals contribute distinct ecological functions. These changes to mammal diversity and distribution over millennia have altered both global patterns in functional diversity and …

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 …

Connecting Climate And Geography With Diversification And Conservation Of A Western North American Endemic Mammal, Sorex Monticola, Antonia Androski

Biology ETDs

Repeated glacial cycles of the Pleistocene initiated complex sequences of divergence and secondary contact with gene flow for many North American species. In my first chapter, I expand our understanding of the phylogeography of the montane shrew, Sorex monticola, with range-wide genetic sampling and geospatial analyses to reconstruct the history of clades within this species and test whether evolutionarily divergent clades occupy distinct abiotic niches. In my second chapter, I build upon these hypotheses, providing the first estimates of evolutionary relationships and timing of diversification based on genome-wide markers. In my third chapter, I use a systematic review of the …

Patterns Of Stand Structure And Species Composition Through Time And Space In A Piñon- Juniper Woodland In The Southwestern Us, Kyle H. Gonterman

Biology ETDs

Piñon- juniper (PJ) woodlands in the Southwest United States are expected to see mortality and structural change in response to climate change. The extent to which this habitat structures itself as well as its response to these changes over time are not well known yet and have not been examined to this extent for the location of this study within the Sevilleta National Wildlife Refuge. Within a small range, we discovered these woodlands consist of persistent woodland, shrubby woodland, and juniper savanna in which structural, spatial, and regeneration patterns differ. In this study, we discovered the specific differences between these …

Sub-Stage Climatic Shifts During Mis 11 Refined From Diatom Assemblage Reconstruction In The Valles Caldera, New Mexico, Savannah Cutler

Earth and Planetary Sciences ETDs

Diatom assemblage reconstruction from the Valles Caldera sediment core (VC-3) was utilized to infer climatic and aquatic changes during a 50-thousand-year [ka] period in the Mid-Pleistocene (435-385 ka). This 50 ka interval spans most of Marine Isotope Stage 11 (MIS 11) – one of the most prominent interglacials of the past 500 ka – and is widely considered an analog for the Holocene and future climate regimes. Nearly all records from MIS 11 are either marine or ice-core based, making VC-3 unique among lacustrine sediment records as it captures insolation variations and climatic changes during the mid-Pleistocene. Analysis of the …

Agroecology And Soil Stewardship: Values And Techniques Of Smallholder Farmers In Bernalillo County, Stephanie Olivas

Geography ETDs

Agrarian movements around the world use agroecology to build sovereignty and steward dynamic ecosystems. Research has shown that agroecological farmers steward more resilient crops, more resilient soil biomes, and greater biodiversity than conventional agriculture. GIS and remote sensing offer many tools to detect the impacts of these farmers on the environment, but it is less clear how such technologies fit into agroecological goals. This study asks: what values, experiences and knowledge do smallholder producers in Bernalillo County embody in their soil stewardship practices? Also, what experience or knowledge do smallholder producers in Bernalillo County have about remote sensing, and would …

Paleoecology Of The Late Cretaceous Western Interior Seaway And Gulf Coastal Plain, Ceara Kathleen Quinn Purcell

Earth and Planetary Sciences ETDs

This dissertation presents research into the paleobiogeography and paleoecology of the Western Interior Seaway (WIS) and Gulf Coastal Plain (GCP) during the Late Cretaceous. The dataset utilized here includes an extensive record of marine invertebrates from over 200 years of fossil collecting and sedimentary data collated from over 45 different literature sources, representing approximately 17 million years of deposition. The high-resolution of this dataset, and its extensive geographic distribution and temporal duration, make it ideal for exploring various ecological questions. Using these data, I have attempted to reconstruct paleobiogeographic provinces as published in prior works, explore functional diversity patterns, and …

Unraveling The Paradox Of The 'Great Speciators': Evolutionary Dynamics Of A Geographic Radiation Of Island Kingfishers (Todiramphus), Jenna Merle Mccullough

Biology ETDs

The paradox of the ‘Great Speciators’ describes a biogeographic pattern in which geographically widespread lineages have strong overwater dispersal capabilities, yet exhibit genetic and phenotypic divergence between islands, suggesting limited dispersal and cessation of gene flow. In my dissertation, I leveraged whole genomes and two comprehensive trait datasets of dispersal ability and plumage coloration of all described diversity within Todiramphus kingfishers, a rapid radiation of largely island endemic ‘Great Speciators.’ Chapter 1 reveals that whole genome datasets do not outright solve the evolutionary relationships of this clade and that widespread incomplete lineage sorting (ILS) and gene flow are sources of …

Crossing The Ocean: The Importance Of Gene Flow In Island Evolution, Ethan F. Gyllenhaal

Biology ETDs

Islands have long been a critical arena for the development of ecological and evolutionary theory, particular due to persistent open-water gaps between them. In this dissertation I demonstrates how these caps are permeable, which can be leveraged to understand evolution on islands and more broadly. The first chapter develops this connection between ongoing, overwater gene flow and island biogeographic theory, and tests it on an archipelago species. The second take a three-pronged approach in demonstrating how over-water gene flow can bias phylogenetic inference, and how many phylogeographic metrics in islands are likely shaped by long-term gene flow. The final two …

The Descent Of Anolis: Assemblages, Convergence, And Ecomorphological Evolution, Christopher G. Anderson

Biology ETDs

The evolutionary outcomes we observe in modern organisms, particularly associations between phenotypes and environments, have been and remain an invaluable tool in interpreting the biological phenomena that shape our world. In the following chapters, I leverage a comprehensive phylogenetic and morphological dataset for 351 species comprising a diverse group of arboreal lizards, the Anolis clade, to explore how communities and morphologies evolve. First, I characterized patterns among coexisting lineages of Anolis to reveal a general pattern of phylogenetic relatedness among lineages comprising assemblages and identify differences attributable to a biogeographic variable. Then I examined the morphological consequences associated with the …

Quantifying The Influences Of Abiotic And Biotic Factors On Post-Fire Vegetation In The Southwestern Us, Joseph Lafayette Crockett

Biology ETDs

The ongoing warming associated with climate change is increasing the flammability of southwestern US dry forests. As larger fractions of the landscape are impacted by high-severity fire, the potential exists for forests to convert to non-forest. Given that the forested area in the southwestern US is an important contributor of ecosystem services, quantifying limitations to vegetation establishment is critical to informing post-fire recovery efforts and understanding how ongoing climate change will limit seedling establishment in the future. To that end, this dissertation focuses on post-fire vegetation recovery of southwestern forests. First, I report on the influence of precipitation and topography …

Evidence Of Competitive Release Following Overstory Mortality In A Semi-Arid Piñon-Juniper Woodland, Corrie D. Gonzalez

Biology ETDs

Extreme temperatures and severe drought events have led to widespread tree mortality worldwide. In semi-arid regions of the Southwest United States, these events pose a significant threat to piñon-juniper (PJ) woodlands. We studied the effects of piñon and juniper mortality on the growth and physiology of existing saplings in PJ woodlands by analyzing water status, photosynthetic activity, and tissue chemistry to gain insights into these impacts. Juniper saplings exhibited improved water status and water use efficiency in response to overstory mortality, whereas piñon saplings did not. Additionally, both piñon and juniper saplings exhibited increased photosynthetic rates, increased photosynthetic capacity, and …

Resolving The Paradox Of Polyploidy: Underexplored Facets Of Polyploid Plants, Benjamin P. Gerstner

Biology ETDs

Polyploidy, or whole genome duplication, is a common phenomenon in plants, but the establishment and persistence of mixed-ploidy populations remains a paradox. This dissertation explores factors that contribute to the persistence and establishment of mixed-ploidy populations in nature. The first chapter investigates the role of unreduced gametes in neopolyploid establishment and finds that variability in their formation rate can have a significant impact on polyploid establishment and persistence. The second chapter searches for evidence of soil microbes exhibiting ploidy-specificity, a pre-condition for microbe-mediated niche differentiation, a possible stabilizing mechanism contributing to ploidy coexistence. Finally, the third chapter tests for microbe-mediated …

Investigation Of Orthohantavirus Genetics In Rodent Reservoirs And Clinical Samples, Samuel Melvin Goodfellow

Biomedical Sciences ETDs

Orthohantaviruses are negative-sense, single stranded RNA viruses with trisegmented genomes that can cause severe disease in humans and are carried by several host reservoirs throughout the world. In the United States, Sin Nombre orthohantavirus (SNV) is the primary cause of hantavirus cardiopulmonary syndrome (HCPS) with a fatality rate of ~36% and the highest cases occuring in the southwest region. The primary SNV host reservoir is thought to be the western deer mouse, Peromyscus maniculatus, however it has been shown that other rodents can carry different orthohantaviruses. We designed a pan-orthohantavirus detection tool to survey several small mammal populations throughout New …

Phylogeographic History Of The Leaf-Eared Mouse, Phyllotis Xanthopygus Complex, Tabitha R. Mcfarland

Biology ETDs

Museum collections provide essential biodiversity sampling needed to understand the species limits, phylogeny, and biogeographic history of mammals, all key features of the foundation for comparative analyses in ecology and evolution. We add to this framework a diverse assemblage of species of leaf-eared mice (genus Phyllotis) in South America and then focus on the Phyllotis xanthopygus complex by combining available mitochondrial sequence (cytochrome b; cytb) data (351 GenBank samples) with 52 newly sequenced museum samples from the northern extent of this complex’s range (51 from Bolivia and 1 from northern Chile) to reconstruct evolutionary relationships using maximum …

Assessing Ecological Relationships Among Late Triassic Vertebrates In Petrified Forest National Park, Alexandra Davis Apgar

Earth and Planetary Sciences ETDs

The complex vertebrate ecosystem of the Late Triassic has not yet been fully understood, largely due to oversimplification of hypothesized trophic hierarchies and limited preservation of direct evidence of faunal interaction. Paleocommunity reconstruction attempts can also fall victim to taphonomic biases, time-averaging inaccuracies, and non-analogue paleoecologies. Utilizing a combination of PAIRS analysis and NMDS ordination, we highlight vertebrate faunal relationships within the Adamanian and Revueltian faunachrons of Petrified Forest National Park, assess the likelihood that these patterns have ecological rather than preservational drivers, and examine how these potential interactions may have been impacted by the Adamanian-Revueltian turnover event. We are …

Social Tolerance, Cooperation, And Constraint Shape Differentiated Social Relationships In Female Chimpanzees, Stephanie A. Fox

Anthropology ETDs

In this dissertation, I investigate variables that promote and constrain female-female social relationships in chimpanzees, a species where females disperse at sexual maturity, reside primarily among non-kin as adults, and where fission fusion social structure can reveal how female social behavior responds to different social contexts. I conducted my research using a combination of detailed behavioural data that I collected during a one-year field season (2019-2020) and long-term data (2010-2019) collected by the Kibale Chimpanzee Project. I show that female chimpanzees form stable, differentiated social relationships, which reflect active preferences and variation in social tolerance (Chapter 2); females leverage these …

Ecological Impacts Of Invasive Crayfish In A Naïve Riparian System, Gregor L. Hamilton

Biology ETDs

Aquatic and riparian food webs are inextricably linked. In deserts, they provide critical energy subsidies to surrounding terrestrial food webs, but these vital subsidies are not guaranteed; streams in arid lands are especially sensitive to perturbations. In this dissertation, I investigated the role of an oft-cited threat to stream communities in the lower Colorado River basin: non-native crayfish. I contributed to methodologies in passive integrated transponder use and length-weight relationships in crayfish to aid future research. I leveraged stable isotope analysis of δ¹⁵N, δ¹³C, and δ²H to understand crayfish role in the food webs. …

Combining Isotopic And Genetic Analyses To Quantify Microbial Facilitation Of Recalcitrant Resource Use By Terrestrial And Aquatic Consumers, Alexi Christina Besser

Biology ETDs

Quantifying the flow of energy and nutrients through food webs is foundational to understanding the structure and function of ecosystems. Here, I utilize the stable carbon and nitrogen isotope analysis of individual amino acids to trace the movement of essential amino acids through terrestrial and freshwater food webs in New Mexico, USA. I first explore isotopic patterns among co-occurring terrestrial plants and aquatic algae. I then combine this molecular isotopic approach with 16S and 18S rRNA sequencing to demonstrate the importance of gut microbiota as sources of essential amino acids to wild mammalian hosts. Next, I explore the roles of …

Above- And Belowground Responses To Environmental Change In The Northern Chihuahuan Desert, Renée Françoise Brown

Biology ETDs

Drylands cover 45% of the terrestrial surface and are expanding rapidly due to anthropogenic drivers. Altered precipitation regimes, atmospheric nitrogen deposition, and wildfire will likely have significant consequences in these regions where ecological processes are limited by water and nitrogen. In this dissertation, I explored temporal dynamics of net primary production (NPP) and related above- and belowground processes under several environmental change drivers in the Sevilleta National Wildlife Refuge, central New Mexico, USA. Located in the northern Chihuahuan Desert, this region experiences strong seasonal precipitation patterns driven by the North American Monsoon, historically characterized by frequent small rain events hypothesized …

Biodiversity And Global Change In Terrestrial Ecosystems, Timothy John Ohlert

Biology ETDs

Terrestrial ecosystems are critical to human and ecological processes but many gaps in our knowledge remain regarding how terrestrial plant communities assemble and respond to global change. I used field experiments distributed around the world, including long-term experiments from the Sevilleta National Wildlife Refuge (SNWR) in New Mexico and deserts of the southwestern U.S., to evaluate the consequences of drought and other abiotic stressors on plant communities. Dominant grasses were particularly important for the productivity and structure of grasslands at SNWR. In general, the structure of desert plant communities had high resistance to extreme drought, though grasses and other perennial …