Ecology and Evolutionary Biology Commons^™

The Effects Of Aboveground Herbivory On Root Traits And Root Decomposition, Emily A. Chavez

All Graduate Theses and Dissertations, Fall 2023 to Present

Soil holds more carbon (C) than the Earth's atmosphere and vegetation combined. Soil loses carbon through soil respiration and releases CO₂ from the soil. The soil respiration rate can vary based on the chemistry of the plant litter inputs and physical factors, such as soil temperature and nutrient content. In Alaska's Yukon-Kuskokwim (YK) Delta, grazing by geese affects the chemistry of plants and the soil's physical qualities, thus altering the rate of soil respiration. Although we know that goose herbivory leads to changes in the rate of soil respiration, we know very little about how goose herbivory affects the …

Deconstructing The Mangrove Carbon Cycle: Gains, Transformation, And Losses, M. F. Adame, N. Cormier, P. Taillardat, N. Iram, A. Rovai, T. M. Sloey, E. S. Yando, J. F. Blanco-Libreros, M. Arnaud, T. Jennerjahn, C. E. Lovelock, D. Friess, G. M. S. Reithmaier, C. A. Buelow, S. M. Muhammad-Nor, R. R. Twilley, R. A. Ribeiro

Biological Sciences Faculty Publications

Mangroves are one of the most carbon-dense forests on the Earth and have been highlighted as key ecosystems for climate change mitigation and adaptation. Hundreds of studies have investigated how mangroves fix, transform, store, and export carbon. Here, we review and synthesize the previously known and emerging carbon pathways in mangroves, including gains (woody biomass accumulation, deadwood accumulation, soil carbon sequestration, root and litterfall production), transformations (food web transfer through herbivory, decomposition), and losses (respiration as CO₂ and CH₄, litterfall export, particulate and dissolved carbon export). We then review the technologies available to measure carbon fluxes in …

Revisiting Trophic Cascades And Aspen Recovery In Northern Yellowstone, Robert L. Beschta, Luke E. Painter, William J. Ripple

Aspen Bibliography

We revisit the nature and extent of trophic cascades and quaking aspen (Populus tremuloides) recovery in the northern range of Yellowstone National Park (YNP), where studies have reported on Rocky Mountain elk (Cervus canadensis) browsing and young aspen heights following the St. John, 1995-96 reintroduction of gray wolves (Canis lupus). A recent study by Brice et al. (2021) expressed concerns about methodologies employed in earlier aspen studies and that results from those studies exaggerated the extent to which a trophic cascade has benefitted aspen, concerns such as: (a) the selection of aspen stands, (b) …

Bison Influences On Composition And Diversity Of Riparian Plant Communities In Yellowstone National Park, J. Boone Kauffman, Dian Lyn Cummings, Cimarron Kauffman, Robert L. Beschta, Jeremy Brooks, Keeley Macneill, William J. Ripple

Aspen Bibliography

Riparian zones are among the most biologically diverse ecosystems in the Intermountain West, USA, and provide valuable ecosystem services, including high rates of biotic productivity, nutrient processing, and carbon storage. Thus, their sustainability is a high priority for land managers. Large ungulates affect composition and structure of riparian/stream ecosystems through herbivory and physical effects, via trailing and trampling. Bison (Bison bison) in Yellowstone National Park (YNP) have been characterized as "ecosystem engineers" because of their demonstrated effects on phenology, aboveground productivity of grasses, and woody vegetation structure. Bison have greatly increased in numbers during the last two decades …

Revisiting Plant Defense-Fitness Trade-Off Hypotheses Using Solanum As A Model Genus, Sakshi Watts, Satinderpal Kaur, Rupesh R. Kariyat

Biology Faculty Publications and Presentations

Plants possess physical and chemical defenses which have been found to deter herbivores that feed and oviposit on them. Despite having wide variety of defenses which can be constitutive or induced, plants are attacked and damaged by insects associated with different mouthparts and feeding habits. Since these defenses are costly, trade-offs for growth and defense traits play an important role in warding off the herbivores, with consequences for plant and herbivore growth, development and fitness. Solanum is a diverse and rich genus comprising of over 1,500 species with economic and ecological importance. Although a large number of studies on Solanum …

Competition And Herbivory Influence The Survival, Growth, And Physiology Of Native Tree Seedlings In The Kentucky Inner Bluegrass Savanna-Woodland, James D. Shaffer

Theses and Dissertations--Biology

Terrestrial plant communities are shaped by competition for resources, herbivory, and abiotic processes. Savanna systems represent a dynamic coexistence of contrasting life forms (grasses and trees) shaped by competition and disturbance. The Kentucky Inner Bluegrass Savanna-Woodland (KIBSW) is described as an open woodland of shade intolerant species; however, climatic, and edaphic conditions can support closed-canopy forest. After European pioneer settlement (c1750-1800), over 99% of “savanna-woodlands” have been lost. KIBSW remnants are experiencing a recruitment failure, leading to a dominance shift in tree communities. I researched how tree-grass competition and mammalian herbivory influence KIBSW regeneration and maintenance. The KIBSW does not …

Vegetation And Nutritional Changes Over 20 Years Of White-Tailed Deer Exclusion, Gabrielle Nicole Ripa

Theses and Dissertations

Knowledge of the impacts of white-tailed deer (Odocoileus virginianus; hereafter deer) as dominant herbivores throughout the Southeastern United States of America is lacking. To address this, three paired experimental units of exclosures and controls were constructed in 2000 on three Wildlife Management Areas across Mississippi within the ecoregions of the Upper Coastal Plain, Lower Coastal Plain, and the Mississippi Alluvial Valley. Vegetation was sampled in the summers of 2000, 2005, and 2021 including vegetation structure, canopy coverage, basal area, and species composition. Additionally, in 2005 and 2021, biomass was sampled to determine potential impacts on nutritional carrying capacity. Among the …

Pando's Pulse: Vital Signs Signal Need For Course Correction At World-Renowned Aspen Forest, Paul C. Rogers

Aspen Bibliography

Upland aspen (Populus spp.) forests contribute significantly to biodiversity in their circumboreal role as keystone species. As aspen ecosystems flourish or diminish, myriad dependent species follow suit. The 43-hectare Pando aspen (Populus tremuloides Michx.) clone in Utah, USA, is thought to be the largest living organism on earth, but is faltering due to chronic herbivory. Long-term resilience in aspen communities, including Pando, rests on successful recruitment of vegetative suckers that are nutritiously desirable to browsing ungulates. Here, I evaluate aspen reproduction alongside numerous vital indicators of Pando's status in the first trend assessment of this embattled iconic forest. …

Understanding How Whole Genome Duplication In Plants Impacts Herbivore-Plant Interactions, Anne Curé

Dissertations - ALL

Herbivory by insect herbivores is a strong selective force in many communities. Although herbivore-plant interactions have been a focus of interest for decades, we are still exploring how large-scale genetic changes in the host plant alters their interactions with insect herbivores. One such prevalent change in plants is whole-genome duplication (WGD), or polyploidy, but we are still learning how WGD affects ecological interactions. In particular, studies of herbivory on polyploids have primarily focused on established polyploid plant populations. Although this approach has yielded exciting results that suggest WGD affects insect herbivores feeding on polyploids, this approach also confounds the effects …

Growth–Defense Trade-Offs Shape Population Genetic Composition In An Iconic Forest Tree Species, Olivia L. Cope, Ken Keefover-Ring, Eric L. Kruger, Richard L. Lindroth

Aspen Bibliography

All organisms experience fundamental conflicts between divergent metabolic processes. In plants, a pivotal conflict occurs between allocation to growth, which accelerates resource acquisition, and to defense, which protects existing tissue against herbivory. Trade-offs between growth and defense traits are not universally observed, and a central prediction of plant evolutionary ecology is that context-dependence of these trade-offs contributes to the maintenance of intraspecific variation in defense [Züst and Agrawal, Annu. Rev. Plant Biol., 68, 513–534 (2017)]. This prediction has rarely been tested, however, and the evolutionary consequences of growth–defense trade-offs in different environments are poorly understood, especially in long-lived species …

Feeding Specificity Of The Photosynthetic Sacoglossan Sea Slug Elysia Papillosa, Kourtney Sui Barber

USF Tampa Graduate Theses and Dissertations

The sacoglossan sea slug, Elysia papillosa is associated with two species of the siphonaceous green alga, Penicillus, which co-occur in mixed macrophyte beds at Tarpon Springs, FL, USA. Field collections revealed that Elysia papillosa is frequently collected from the alga, P. capitatus, but is also present in much lower abundance on P. lamourouxii. Past studies have shown that some species of sacoglossans consume algal species that differ from the algae from which they are collected so, in order to determine whether E. papillosa was consuming either or both species of Penicillus, total DNA was extracted from individual slugs collected from …

Nutrient Availability Controls The Impact Of Mammalian Herbivores On Soil Carbon And Nitrogen Pools In Grasslands, Judith Sitters, E. R. Jasper Wubs, Elisabeth S. Bakker, Thomas W. Crowther, Peter B. Adler, Sumanta Bagchi, Jonathan D. Bakker, Lori Biederman, Elizabeth T. Borer, Elsa E. Cleland, Nico Eisenhauer, Jennifer Firn, Laureano Gherardi, Nicole Hagenah, Yann Hautier, Et Al.

Ecology Center Publications

Grasslands are subject to considerable alteration due to human activities globally, including widespread changes in populations and composition of large mammalian herbivores and elevated supply of nutrients. Grassland soils remain important reservoirs of carbon (C) and nitrogen (N). Herbivores may affect both C and N pools and these changes likely interact with increases in soil nutrient availability. Given the scale of grassland soil fluxes, such changes can have striking consequences for atmospheric C concentrations and the climate. Here, we use the Nutrient Network experiment to examine the responses of soil C and N pools to mammalian herbivore exclusion across 22 …

Bottom-Up Herbivore-Plant Feedbacks Trump Trophic Cascades In A Wolf-Elk-Grassland System, Trevor C. Weeks

Undergraduate Theses, Professional Papers, and Capstone Artifacts

Top-down predator-prey effects that alter the abundance, biomass, or productivity of a population community across more than one link in a food web are referred to as trophic cascades. While these effects have been extensively studied in aquatic environments, fewer studies have examined trophic cascades in terrestrial ecosystems. And fewer still terrestrial studies have tested for trophic cascades between vertebrates and grassland vegetation. Across the globe, grassland plant biomass is driven by both precipitation and non-linear positive feedbacks between grazing and plant productivity, as predicted by the Intermediate Grazing Hypothesis. Yet little is known about the role that apex carnivores …

Past Management Spurs Differential Plant Communities Within A Giant Single-Clone Aspen Forest, Paul C. Rogers, Jan ŠEbesta

Ecology Center Publications

Sustainable aspen ecosystems hold great promise for global biodiversity conservation. These forests harbor relatively high species diversity, yet are threatened by fire suppression, land development, timber-focused management, extended droughts, and chronic herbivory. “Pando” is a high-profile quaking aspen (Populus tremuloides) forest in Utah, USA which is putatively the ‘largest living organism on earth.’ Pando comprises an estimated 47,000 genetically identical stems, but is threatened by human impacts. Our interest in the present study is whether changes to the giant organism were affecting understorey vegetation and whether discrete zones are displaying divergent community compositions. For instance, recent research has demonstrated strong …

Ecological Responses Of Seascape Heterogeneity, Dinorah H. Chacin

USF Tampa Graduate Theses and Dissertations

A core aim of landscape ecologists as well as conservation and management practices has been to understand how processes that structure communities vary as a function of landscape context. Landscape heterogeneity (i.e. landscape composition, configuration) and fine-scale habitat characteristics can influence ecological interactions across habitat patches at a range of scales. Therefore, the main objective of this work is to apply a landscape ecology perspective to understand how seascape heterogeneity can influence demographic rates, community patterns, and ecological processes. To accomplish this overall goal, I conducted a literature review on oyster reefs from a seascape ecology perspective (Chapter 1) and …

Marine Reserves Shape Seascapes On Scales Visible From Space, Elizabeth M. P. Madin, Alastair R. Harborne, Aaron M. T. Harmer, Osmar J. Luiz, Trisha Brooke Atwood, Brian J. Sullivan, Joshua S. Madin

Watershed Sciences Faculty Publications

Marine reserves can effectively restore harvested populations, and ‘mega-reserves’ increasingly protect large tracts of ocean. However, no method exists of monitoring ecological responses at this large scale. Herbivory is a key mechanism structuring ecosystems, and this consumer–resource interaction's strength on coral reefs can indicate ecosystem health. We screened 1372, and measured features of 214, reefs throughout Australia's Great Barrier Reef using high-resolution satellite imagery, combined with remote underwater videography and assays on a subset, to quantify the prevalence, size and potential causes of ‘grazing halos’. Halos are known to be seascape-scale footprints of herbivory and other ecological interactions. Here we …

Migratory Goose Arrival Time Plays A Larger Role In Influencing Forage Quality Than Advancing Springs In An Arctic Coastal Wetland, Karen H. Beard, Ryan T. Choi, A. Joshua Leffler, Lindsay G. Carlson, Katharine C. Kelsey, Joel A. Schmutz, Jeffrey M. Welker

Ecology Center Publications

With warmer springs, herbivores migrating to Arctic breeding grounds may experience phenological mismatches between their energy demands and the availability of high quality forage. Yet, how the timing of the start of the season and herbivore arrival influences forage quality is often unknown. In coastal western Alaska, approximately one million migratory geese arrive each spring to breed, where foliar %N and C:N ratios are linked to gosling survival and population growth. We conducted a three-year experiment where we manipulated the start of the growing season using warming chambers and grazing times using captive Pacific black brant (Branta bernicla nigricans) to …

High Phenolic Content Fails To Deter Mesograzer Consumption Of Myriophyllum Spicatum (Eurasian Watermilfoil) In New England, Latina Steele, Courtney Ray, Michele Guidone

Biology Faculty Publications

Eurasian watermilfoil (Myriophyllum spicatum) is often considered one of the most aggressive macrophyte invaders in freshwater habitats throughout the United States. However, conditions leading to successful milfoil invasions are not well understood. This study sought to illuminate the role of 4 herbivores in determining milfoil invasion success via either enemy release or biotic resistance. We determined feeding preferences of three herbivores native to the northeastern United States and measured milfoil phenolic content, which may act as an herbivore feeding deterrent. We found that phenolic content in milfoil was two times higher than in two of the most abundant native macrophytes …

Mule Deer Impede Pando’S Recovery: Implications For Aspen Resilience From A Single-Genotype Forest, Paul C. Rogers, Darren J. Mcavoy

Ecology Center Publications

Aspen ecosystems (upland Populus-dominated forests) support diverse species assemblages in many parts of the northern hemisphere, yet are imperiled by common stressors. Extended drought, fire suppression, human development, and chronic herbivory serve to limit the sustainability of this keystone species. Here we assess conditions at a renowned quaking aspen (Populus tremuloides) grove—purportedly the largest living organism on earth—with ramifications for aspen biogeography globally. The “Pando” clone is 43 ha and estimated to contain 47,000 genetically identical aspen ramets. This iconic forest is threatened in particular by herbivory, and current management activities aim to reverse the potential for …

Aspen Recruitment In The Yellowstone Region Linked To Reduced Herbivory After Large Carnivore Restoration, Luke E. Painter, Robert L. Beschta, Eric J. Larsen, William J. Ripple

Aspen Bibliography

Quaking aspen (Populus tremuloides) recruitment during the 1980s–90s was suppressed by Rocky Mountain elk (Cervus canadensis) herbivory on winter ranges in the Yellowstone region, and saplings (young aspen taller than 2 m) were rare. Following the 1995–96 reintroduction of gray wolves (Canis lupus), browsing decreased and sapling recruitment increased in Yellowstone National Park. We compared aspen data from inside the park to data collected in three winter ranges outside the park. For most areas, the percentage of young aspen browsed annually was 80–100% in 1997–98, decreasing to 30–60% in 2011–15. Sapling recruitment was inversely …

Predators Shape Sedimentary Organic Carbon Storage In A Coral Reef Ecosystem, Trisha Brooke Atwood, Elizabeth M. P. Madin, Alastair R. Harborne, Edd Hammill, Osmar J. Luiz, Quinn R. Ollivier, Chris M. Roelfsema, Peter I. Macreadie, Catherine E. Lovelock

Watershed Sciences Faculty Publications

Trophic cascade theory predicts that predator effects should extend to influence carbon cycling in ecosystems. Yet, there has been little empirical evidence in natural ecosystems to support this hypothesis. Here, we use a naturally-occurring trophic cascade to provide evidence that predators help protect sedimentary organic carbon stocks in coral reef ecosystems. Our results show that predation risk altered the behavior of herbivorous fish, whereby it constrained grazing to areas close to the refuge of the patch reefs. Macroalgae growing in “riskier” areas further away from the reef were released from grazing pressure, which subsequently promoted carbon accumulation in the sediments …

Gynodioecy And Biotic Interactions: Plant Traits, Insect Preferences, And Population-Level Consequences, Laura A. D. Doubleday

Doctoral Dissertations

In species with distinct sexes, differences between the sexes often affect interspecific interactions. In gynodioecious flowering plants, where individuals are female or hermaphrodite, both pollinators and herbivores tend to prefer hermaphrodites. Because pollinators and herbivores affect plant fitness, their preferences have consequences for plant mating patterns, natural selection on mating-related traits, and plant breeding system evolution. Being sessile, the spatial arrangement of females and hermaphrodites in gynodioecious plant populations alters conspecific density and sex ratio locally, which can also have important fitness effects. My dissertation combines observational studies in natural Silene vulgaris populations and simulation modeling to address questions about …

The Adaptive Evolution Of Herbivory In Freshwater Systems, Jessica Lynn Sanchez Montelongo

FIU Electronic Theses and Dissertations

Herbivory is thought to be nutritionally inefficient relative to carnivory and omnivory. But, herbivory evolved from carnivory in many lineages, suggesting that there are advantages to eating plants. To understand the adaptive significance of the transition from carnivory to herbivory, I proposed five hypotheses for the adaptive evolution of herbivory and reviewed the current freshwater literature to identify conditions where eating plants might be adaptive over eating animals. I tested three of these ideas (Suboptimal Habitat, Heterotroph Facilitation, and Lipid Allocation) using the herbivorous Sailfin Molly (Poecilia latipinna)and identified each as a potential mechanism for the evolution of …

The Effects Of Gopher Tortoise (Gopherus Polyphemus) Herbivory On Plant Community Composition And Seed Germination, And The Effects Of Gut Passage On The Germinability Of Seeds: A Meta-Analysis, Jason C. Richardson

USF Tampa Graduate Theses and Dissertations

Herbivory produces direct and indirect effects on plants and at different spatial scales will have varied consequences. Consumption of plants by vertebrate grazers may affect the plants on an organismal level through direct mortality, on a community level by changing species composition or by altering the rate of succession, and even at a whole ecosystem level by altering nutrient cycles.

The majority of the scientific literature has focused extensively on herbivory by mammals and birds. With regard to mammals, studies have shown how folivory affects individual plants, plant populations, and communities of plants.

Mammals, as well as birds, also ingest …

The Role Of Ferric Reduction Oxidases In Plant Anti-Herbivore Defense., Virginia C. Nunamaker

College of Arts & Sciences Senior Honors Theses

Iron is an essential element required for plants to carry out metabolic functions such as photosynthesis, heme biosynthesis, and chlorophyll biosynthesis. Within Arabidopsis thaliana, eight ferric reduction oxidase (FRO) genes function in iron uptake and homeostasis with tissue specific expression. However, little else is known regarding the biological role of FROs. Recent studies identify the FRO gene family as particularly responsive to the green leaf plant derived volatile (GLV) cis-3-hexenyl acetate (z3HAC). Since z3HAC acts as a wound signal and cues unaffected parts of the plant to prime defenses prior to herbivory, an increase in FRO activity in response …

The Effect Of Simulated Herbivory On Pea Plants (Pisum Sativum) Under Water Stress, Georgia Harrison

Conspectus Borealis

No abstract provided.

Specialization And Trade-Offs In Plant-Feeding Insects, Daniel Peterson

Doctoral Dissertations

The immense diversity of life on Earth has been attributed to the partitioning of available resources into ecological niches, but it is not obvious what determines the niche size of each species. For example, most plant-feeding insects consume only one or a few closely-related host-plant species despite the advantages of having a broader diet. Many researchers have therefore suggested that the evolution of broad diets in plant-feeding insects must be constrained by genetic trade-offs between adaptations to alternative host-plants. Despite its intuitive feel, however, little empirical evidence in support of the trade-off hypothesis has emerged from decades of experimental studies …

Marine Reserves Promote Coral Reef Resilience By Mitigating Human Impacts Through The Restoration Of Parrotfish Populations, Increasing Their Reproductive Output And Seeding Neighboring Overfished Reefs, Brian L. Stockwell

Biological Sciences Theses & Dissertations

Coral reefs are some of the most productive ecosystems on the planet, providing fisheries resources for over a billion people with billions of dollars in revenue from tourism for developing nations. Coral reefs are under threat from overfishing and water pollution, resulting in less productive algae dominated reefs. Marine reserves are widely expected to promote the resilience of reefs by protecting and increasing the abundance of herbivorous fishes that can graze on algae, therefore directly or indirectly preventing coral to algal phase shifts. However, the ability of marine reserves to mitigate human impacts, restore herbivorous fish populations and seed nearby …

Effects Of Livestock Grazing On Rangeland Biodiversity: A Meta-Analysis Of Grouse Populations, Seth J. Dettenmaier, Terry A. Messmer, Torre J. Hovick, David K. Dahlgren

Wildland Resources Faculty Publications

Livestock grazing affects over 60% of the world’s agricultural lands and can influence rangeland ecosystem services and the quantity and quality of wildlife habitat, resulting in changes in biodiversity. Concomitantly, livestock grazing has the potential to be detrimental to some wildlife species while benefiting other rangeland organisms. Many imperiled grouse species require rangeland landscapes that exhibit diverse vegetation structure and composition to complete their life cycle. However, because of declining populations and reduced distributions, grouse are increasingly becoming a worldwide conservation concern. Grouse, as a suite of upland gamebirds, are often considered an umbrella species for other wildlife and thus …

Natural Enemies Partially Compensate For Warming Induced Excess Herbivory In An Organic Growth System, Orsolya Beleznai, Jamin Dreyer, Zoltán Tóth, Ferenc Samu

Entomology Faculty Publications

Predators can limit prey abundance and/or levels of activity. The magnitudes of these effects are contingent on predator and prey traits that may change with environmental conditions. Aberrant thermal regimes could disrupt pest suppression through asymmetric effects, e.g. heat-sensitive predator vs. heat-tolerant prey. To explore potential effects of warming on suppressing pests and controlling herbivory in a vegetable crop, we performed laboratory experiments exposing an important pest species to two spider predator species at different temperatures. Heat tolerance was characterised by the critical thermal maxima parameter (CTM50) of the cucumber beetle (Diabrotica undecimpunctata), wolf spider (Tigrosa helluo …