Life Sciences Commons^™

Climate Change And Grasslands: Ecosystem-Level Responses To Elevated Carbon Dioxide, Clenton E. Owensby

IGC Proceedings (1993-2023)

Elevated CO2 is the major greenhouse gas associated with global climate change. The impact of increasing atmospheric CO2 on grassland ecosystems has been studied little. Studies with single plants or populations in controlled environments have provided knowledge of the mechanisms involved in plant response to elevated CO21 but without ecosystem-level studies over an extended period, we will be unable to make any valid predictions. Primary production of grassland ecosystems under elevated CO2 will likely increase, with the greatest increase coming with C3-dominated plant communities, or plant communities that are .subjected to frequent drought stress. Increased nitrogen-use efficiency and reduced nitrogen …

Herbivore Effects On Litter Quality And Quantity And Influences On Carbon Cycling, Taylor Saunders

All Graduate Theses and Dissertations, Fall 2023 to Present

Plants are responsible for a large amount of the movement of carbon (C) and nitrogen (N) through terrestrial systems. One way that plants affect the movement of C and N is through plant litter inputs to soils. Plant litter highly influences processes such as soil microbial respiration and decomposition. Herbivores, such as geese in the Yukon Delta National Wildlife Refuge, affect these processes by changing litter quality and quantity. These changes cause differences in soil respiration, microbial communities, and nutrient turnover. However, because geese influence litter quality, quantity, and habitat characteristics simultaneously, it is not yet clear which of these …

Socially Valued, Ecologically In Decline: Place Attachment Influences Support For Management Actions In A Quaking Aspen Forest Impacted By Recreation, Soil Contamination, And Ungulates, Georgie Corkery

All Graduate Theses and Dissertations, Fall 2023 to Present

Quaking aspen (Populus tremuloides Michx.) spark strong emotional attachments among many people, yet they are ecologically in decline across North America. Aspen landscapes are also popular outdoor recreation destinations. Site-specific strategies are required for both managing for healthy aspen landscapes and enhancing the outdoor recreation experience. Our study investigated a highly-recreated and ecologically declining aspen forest in Summit County, Utah facing population decline. There were two distinct phases of data collection. First, we evaluated the condition of the aspen and identified potential management actions that could improve the condition of the aspen. Second, we surveyed people who visited the site …

Nitrogen Nutrition Of Brant (Branta Bernicla L.) Grazing On Saltmarsh And Pasture Species, G Q.A Anderson, M Andrews, S M. Percival, J S. Kirby

IGC Proceedings (1993-2023)

Captive brant Branta bernicla were fed a range of food plants to determine their ability to digest nitrogen and specifically soluble protein. Soluble protein levels in droppings were only a small fraction of those in plants, indicating substantial uptake or conversion. For white clover Trifolium repens L., uric acid content indicated that at least 50% of excreted nitrogen had been metabolised, strongly suggesting that a substantial fraction of soluble protein is utilised by the geese. Carbon/nitrogen ratios increased from plants to droppings while carbon/hydrogen ratios remained nearly constant indicating greater uptake of nitrogen relative to carbon. T. repens was found …

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 …

Theoretical And Observed Relationships Between Defoliation And Partitioning In Grasses, C P.D. Birch, B Thornton

IGC Proceedings (1993-2023)

A model is presented that analyses the potential effect of vertebrate grazing on the partitioning of grasses. Its conclusions are: 1) When grazing is sufficiently frequent and severe, grasses can increase their net increase in biomass by partitioning growth to reserves. 2) Partitioning growth to reserves greatly reduces leaf growth between defoliations. After repeated clipping, dryland browntop (Agrostis castellana) and red fescue (Festuca rubra) allocated a smaller proportion of growth between defoliations to leaves than ryegrass (Lolium perenne) or rough meadow-grass (Poa trivialis). Browntop and fescue achieved less leaf growth than ryegrass …

Aspen Recovery In Northern Yellowstone: A Comment On Brice Et Al. (2021), Luke E. Painter, Robert L. Beschta, William J. Ripple

Aspen Bibliography

Aspen sapling recruitment increased as browsing by elk decreased, following the 1995–96 reintroduction of wolves in Yellowstone National Park. We address claims by Brice et al. (2021) that previous studies exaggerated recent aspen recovery. We conclude that their results actually supported previous work showing a trophic cascade benefiting aspen.

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 …

Stressed, But Doing Fine. An Investigation Of Apocynum Canabinum Patches And Individuals, Lauren Kyburz, Lily Monnett, Quincie Simmons, Dana Dudle

Annual Student Research Poster Session

Apocynum cannabinum (hemp dogbane) is a native Indiana plant that is abundant in the DePauw University Nature Park’s quarry, a heterogeneous site that contains stretches of dry, rocky terrain in addition to many temporary ponds. In 2023, I mapped the distribution of A. cannabinum in the quarry to see if its habitats are associated with elevation and/or the presence of temporary ponds. I also conducted a study of diurnal pollinator visitation, and an examination of damage caused by the dogbane saucrobotys moth (Saucrobotys futilalis).

Meta-Analysis Of The Effects Of Endophytes And Their Secondary Metabolites On Herbivory From Insects, Derrick Taylor

All Theses

Endophyte-infected plants have reduced the level of herbivory. The defense to herbivory can vary due to the metabolites in the plant and the method of feeding from the pest. Secondary metabolites produced by the endophytes are mainly alkaloids. The associations between endophytes and some alkaloid groups are studied in greater detail. The lack of research of certain alkaloid groups ultimately means that some alkaloids had more data that could be analyzed. As a result, the alkaloid groups were not evenly represented in the meta-analysis. The meta-analysis analyzed the relative effectiveness of the metabolites or endophytes in each of the articles …

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 …

Are Epicuticular Waxes A Surface Defense Comparable To Trichomes? A Test Using Two Solanum Species And A Specialist Herbivore., Sakshi Watts, Rupesh R. Kariyat

Biology Faculty Publications and Presentations

Although plants possess a suite of structural defenses, most studies have focused on trichomes. Trichomes can have both pre- and post-ingestive effects and have been consistently found to reduce herbivory. Along with trichomes, a few studies have focused on epicuticular waxes as an important defense; however, manipulated comparisons examining herbivore growth and development is limited. In this study, using two Solanum species (Solanum glaucescens and Solanum macrocarpon) that vary in both defenses, we tested the hypothesis that variation in defenses will affect herbivore feeding, primarily by restricting feeding commencement. We used electron microscopy together with a series of plant- and …

The Influence Of Abiotic And Biotic Conditions On Lifecycle Stages Is Critical For Estuarine Seagrass Resilience, Chanelle Webster, Paul S. Lavery, Caitlyn O'Dea, Marta Sanchez Alarcon, Chandra Salgado Kent, Mcmahon

Research outputs 2022 to 2026

Abiotic and biotic factors influence seagrass resilience, but the strength and relative importance of the effects are rarely assessed over the complete lifecycle. This study examined the effects of abiotic (salinity, temperature, water depth) and biotic (grazing by black swans) factors on Ruppia spp. over the complete lifecycle. Structures were set up in two estuaries ( – 33.637020, 115.412608) that prevented and allowed natural swan grazing of the seagrasses in May 2019, before the start of the growing season. The density of life stage(s) was measured from June 2019 when germination commenced through to January 2020 when most of the …

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 …

A Field Synopsis, Systematic Review, And Meta-Analyses Of Cophylogenetic Studies: What Is Affecting Congruence Between Phylogenies?, Valeria Trivellone, Bernd Panassiti

MANTER: Journal of Parasite Biodiversity

We conducted a field synopsis and systematic meta-analysis of studies that carried out cophylogenetic analyses using algorithms and available software. We evaluated the influence of three factors—namely, cophylogenetic method, association, and ecosystem type—on the outcome of the analyses, that is, the degree of congruence between phylogenies of interacting species.

The published papers were identified using 4 different databases and 13 keywords; we included all studies for which statistical approaches to compare phylogenies (cophylogenetic analyses) of interacting lineages were used. After the initial screening, 296 studies were selected to extract response variable (outcome of the cophylogenetic analyses, i.e., congruent, incongruent, or …

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. …

Increased Extent Of Waterfowl Grazing Lengthens The Recovery Time Of A Colonizing Seagrass (Halophila Ovalis) With Implications For Seagrass Resilience, Caitlyn M. O’Dea, Paul S. Lavery, Chanelle L. Webster, Kathryn M. Mcmahon

Research outputs 2022 to 2026

Herbivore distributions and abundance are shifting because of climate change, leading to intensified grazing pressure on foundation species such as seagrasses. This, combined with rapidly increasing magnitudes of change in estuarine ecosystems, may affect seagrass resilience. While the overall resilience of seagrasses is generally well-studied, the timeframes of recovery has received comparatively little attention, particularly in temperate estuaries. We investigated how the recovery time (RT) of seagrass is affected by simulated grazing in a southwestern Australian estuary. Whilst excluding swans, we simulated different grazing intensities (25, 50, 75, and 100 % removal from 1 m2 plots) at four locations in …

Drought Tolerance Of Artemisia Tridentata In Response To Herbivory And Mycorrhizal Colonization, Mathew Geisler

Boise State University Theses and Dissertations

Interactions with other organisms can affect a plant’s ability to cope with drought. The re-establishment of Artemisia tridentata, a keystone species of the sagebrush steppe, is often limited by summer drought. This study investigated the effect of two biotic factors, herbivory and symbiosis with arbuscular mycorrhizal fungi (AMF), on the drought tolerance of Artemisia tridentata ssp. wyomingensis (Wyoming big sagebrush) seedlings. For this purpose, I conducted two separate but concurrent field experiments. The herbivory experiment had three treatments: seedlings without tree protectors and seedlings within Vexar or metal-mesh tree protectors. In the mycorrhizal experiment, all seedlings were within metal-mesh …

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 …

Investigation Into The Responses Of Physcomitrella Patens To Herbivory And The Influence Of Light On The Production Of Defense Compounds, Matthew Morris

Undergraduate Honors Thesis Collection

Plant defense mechanisms are well studied in many agriculturally relevant crops such as corn and tomatoes. Though less studied, the more ancestral nonvascular plants may be able to provide insights into the origin and working of modern plant defense systems. In this study, the bryophyte Physcomitrella patens was researched and the role of the jasmonic acid pathway in response to herbivory was investigated. Additionally, the impact of light intensity on the efficacy of this pathway was to be determined. After exposing the moss to various chemical elicitors and mechanical wounding, the activity of proteins produced in the JA pathway was …

Native And Non-Native Plant Species Differentially Affect Arthropod Community Dynamics With Consequences For Crop Production In Lower Rio Grande Valley, Kaitlynn Lavallee, Pushpa G. Soti, Alexis Racelis, Rupesh R. Kariyat

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

In agricultural ecosystems, arthropods play critical roles- including biocontrol, pollination services, and as herbivores. While herbivory negatively affects crop production, the recent decline in beneficial insect numbers have created a global concern, and consequently have led into multiple lines of conservation strategies. Agroecological practices that can provide sustenance, nesting, and refuge for beneficial organisms are considered as some of them, except we lack a better understanding of how seasonal and crop specific variation can affect their community dynamics. In this study, we examined this by investigating how native and non-native plants, when incorporated into a vegetable agroecosystem in Lower Rio …

Soil Biodiversity, Root Herbivory And Carbon And Nitrogen Cycling In Grassland Soils, R. Cook, L. A. Dawson, A. C. Gange, S. J. Grayston, P. J. Murray, A. M. Treonis

IGC Proceedings (1993-2023)

This paper describes research on the relationships between grassland management practices and the diversity of biological communities in soil. Observations are being made in field trials with applications of nitrogen and lime and of insecticide to an original diverse sward and to a single species grass re-seed. The treatments are designed to produce different degrees of diversity in communities of soil animals and microbes. Assessments are being made over three years of the effects on the populations, activity and diversity of root-feeding animals, arbuscular mycorrhizal fungi, soil bacteria, fungi and micro fauna, including nonplant feeding nematodes. Associated laboratory experiments assess …

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 …

Deciphering The Role Of Ion Channels In Early Defense Signaling Against Herbivorous Insects, Akanksha Gandhi, Rupesh R. Kariyat, Amaravadhi Harikishore, Marzieh Ayati, Anirban Bhunia, Nirakar Sahoo

Biology Faculty Publications and Presentations

Plants and insect herbivores are in a relentless battle to outwit each other. Plants have evolved various strategies to detect herbivores and mount an effective defense system against them. These defenses include physical and structural barriers such as spines, trichomes, cuticle, or chemical compounds, including secondary metabolites such as phenolics and terpenes. Plants perceive herbivory by both mechanical and chemical means. Mechanical sensing can occur through the perception of insect biting, piercing, or chewing, while chemical signaling occurs through the perception of various herbivore-derived compounds such as oral secretions (OS) or regurgitant, insect excreta (frass), or oviposition fluids. Interestingly, ion …

Dogbane Under Stress: Habitat Differentiation Of Anthocyanins In Apocynum Cannabinum, Marie Spehlmann '22, Rose Keith Phd

Annual Student Research Poster Session

The quarry in DePauw’s Nature Park, which was previously stripped of soil and layers of bedrock, offers an ideal study system for understanding how plants adapt to disturbances. The quarry bottom is particularly stressful for plants because of this loss in soil, high variability in water availability due to the poor porosity of the bedrock, and high light intensity. Therefore, plants that live there must have traits suitable for this harsh environment. One response elicited to stress in plants is the production of red pigments called anthocyanins. Anthocyanins are versatile and have been found to be protective in a multitude …

Fear Effects And Group Size Interact To Shape Herbivory On Coral Reefs, Andrew G. Bauman, Andrew S. Hoey, Glenn Dunshea, Jenny Fong, Ian Z. W. Chan, Peter A. Todd

Marine & Environmental Sciences Faculty Articles

1. Fear of predators (‘fear effects’) is an important determinant of foraging decisions by consumers across a range of ecosystems. Group size is one of the main behavioural mechanisms for mitigating fear effects while also providing foraging benefits to group members. Within coral reef ecosystems, fear effects have been shown to influence the feeding rates of herbivorous fishes, a key functional group that prevents macroalgal overgrowth. Yet, how fear effects and group size interact to shape macroalgal removal on coral reefs remains unclear.
2. Here, we conducted field-based experiments using models of a common piscivorous fish, the leopard coral grouper Plectropomus leopardus …

Poplar Allene Oxide Synthase 1 Gene Promoter Drives Rapid And Localized Expression By Wounding, Bin Lei, Christopher J. Frost, Tao Xu, Joshua Herr, John E. Carlson, Haiying Liang

Department of Plant Pathology: Faculty Publications

Promoters play critical roles in controlling the transcription of genes and are important as tools to drive heterologous expression for biotechnological applications. In addition to core transcription factor-binding motifs that assist in the binding of RNA polymerases, there are specific nucleotide sequences in a promoter region to allow regulation of gene expression. The allene oxide synthase (AOS) gene family are cytochrome P450s that are responsive to a variety of environmental stress, making them good candidates for the discovery of inducible promoters. Populus AOS homologs separate phylogenetically into two clades. Based on the 19 promoter motifs with significant abundance differences between …