Life Sciences Commons^™

Context-Dependency And Sex-Specificity Of Dispersal Syndromes, Allyssa Kilanowski

Theses and Dissertations--Biology

For populations in landscapes with increasingly heterogeneous and fragmented habitat patches (e.g., metapopulations), dispersal is an important behavior that leads to gene flow and connectivity among isolated patches. Because dispersal is a complex process, there are many traits involved. When suites of morphological, behavioral, physiological, and life-history traits covary with dispersal (e.g., a dispersal syndrome), the correlated traits can assist dispersing individuals through the complex process. Furthermore, once dispersal is completed, the correlated traits can influence the fitness of those dispersed individuals. Dispersal syndromes will likely interact with the local environment to produce ecological and evolutionary feedbacks on the metapopulation. …

Parental Effects On Offspring Reaction Norms: Consequences For Complex Phenotypes In Variable Environments, Alexandra G. Cones

Theses and Dissertations--Biology

Organismal traits all exhibit some degree of environmental sensitivity, and both the strength and direction of these phenotypically plastic responses to the environment can evolve in adaptive ways. For example, parents can use information about their own environment to precondition the traits of their offspring so that they thrive in their future environment. This transgenerational plasticity can also alter the plasticity of offspring, but explicit investigations of this specific phenomenon are rare. I begin with a review of the literature and provide a quantitative genetic framework to investigate this phenomenon, which I then explore empirically using avian embryos. The metabolic …

Multilevel Phenotypic Integration Of Metabolism And Behavior In House Sparrows And Mice, Tim Salzman

Theses and Dissertations--Biology

Patterns of multilevel variation in behavior, both within and among individuals, raise challenging questions about underlying mechanisms and the selective pressures acting on them. One intriguing hypothesis is that physiology shows parallel multilevel variation, and so might represent a latent trait that integrates multilevel behavioral responses. For example, foraging acquires the fuel needed to maintain metabolism, and in turn, an individual’s metabolism affects expression of foraging, and other, behaviors. Metabolism and behavior thus might coevolve to become integrated traits. Despite the appeal of this hypothesis, numerous investigations into the link between metabolism and behavior have yielded largely equivocal results.

To …

Brain Glycogen – Beyond Energy Storage In Glycogen Storage Diseases, Kia H. Markussen

Theses and Dissertations--Molecular and Cellular Biochemistry

Glycogen is a carbohydrate molecule that is traditionally viewed as a convenient and easily accessible energy storage form of glucose. However,emerging evidence supports the role of glycogen as more than a glucose storage form. During the last 20 years, glycogen has been shown to play pivotal roles in learning and memory, signaling events, viscosity, protein glycosylation, and be acritical hallmark in devastating diseases. Not only, does glycogen play a role as an energy substrate and critical metabolite during energy deprivation, glycogen is central for neurotransmitter homeostasis, tumor initiation, and ontributes to proper protein glycosylation in the brain. In this work, …

Improving Baking Quality Of Soft Red Winter Wheat In Kentucky Through Breeding And Sulfur-Nitrogen Fertility Management, Maria Paula Castellari

Theses and Dissertations--Plant and Soil Sciences

Soft Red Winter (SRW) wheat is an important crop grown on about 400,000 acres in Kentucky as a pivotal cash crop in the 3-crops-in-2-years rotation of corn, wheat, and soybean. The humid environment of Kentucky generates a high yielding wheat crop, with low protein concentration and weak gluten strength. This wheat is mainly sold to millers and used by the industry for cakes, pastries, cookies, and crackers. Conversely, there is a rapidly growing interest in identifying other value-added markets for this wheat different to commodity commercialization, such as artisan-baked goods and craft-distilled beverages. Evaluating the quality characteristics of wheat grown …

Metabolic Reprogramming Driven By Ezh2 Inhibition Depends On Cell–Matrix Interactions, Teresa W-M Fan, Jahid M. M. Islam, Richard M. Higashi, Penghui Lin, Christine F. Brainson, Andrew N. Lane

Markey Cancer Center Faculty Publications

EZH2 (Enhancer of Zeste Homolog 2), a subunit of Poly- comb Repressive Complex 2 (PRC2), catalyzes the trimethyla- tion of histone H3 at lysine 27 (H3K27me3), which represses expression of genes. It also has PRC2-independent functions, including transcriptional coactivation of oncogenes, and is frequently overexpressed in lung cancers. Clinically, EZH2 in- hibition can be achieved with the FDA-approved drug EPZ- 6438 (tazemetostat). To realize the full potential of EZH2 blockade, it is critical to understand how cell-cell/cell-matrix interactions present in 3D tissue and cell culture systems in- fluences this blockade in terms of growth-related metabolic functions. Here, we show that …

A Monoadduct Generating Ru(Ii) Complex Induces Ribosome Biogenesis Stress And Is A Molecular Mimic Of Phenanthriplatin, Richard Joseph Mitchell, Sarah M. Kriger, Alexander D. Fenton, Dmytro Havrylyuk, Ankit Pandeya, Yang Sun, Tami Smith, Jason E. Derouchey, David K. Heidary, Edith C. Glazer

Markey Cancer Center Faculty Publications

Ruthenium complexes are often investigated as potential replacements for platinum-based chemotherapeutics in hopes of identifying systems with improved tolerability in vivo and reduced susceptibility to cellular resistance mechanisms. Inspired by phenanthriplatin, a non-traditional platinum agent that contains only one labile ligand, monofunctional ruthenium polypyridyl agents have been developed, but until now, few demonstrated promising anticancer activity. Here we introduce a potent new scaffold, based on [Ru(tpy)(dip)Cl]Cl (tpy = 2,20:60,200-terpyridine and dip = 4,7-diphenyl-1,10-phenanthroline) in pursuit of effective Ru(II )-based monofunctional agents. Notably, the extension of the terpyridine at the 40 position with an aromatic ring resulted in a molecule that …

Bilirubin Levels Are Negatively Correlated With Adiposity In Obese Men And Women, And Its Catabolized Product, Urobilin, Is Positively Associated With Insulin Resistance, Zachary A. Kipp, Mei Xu, Evelyn A. Bates, Wang-Hsin Lee, Philip A. Kern, Terry D. Hinds Jr.

Markey Cancer Center Faculty Publications

Bilirubin levels in obese humans and rodents have been shown to be lower than in their lean counterparts. Some studies have proposed that the glucuronyl UGT1A1 enzyme that clears bilirubin from the blood increases in the liver with obesity. UGT1A1 clearance of bilirubin allows more conjugated bilirubin to enter the intestine, where it is catabolized into urobilin, which can be then absorbed via the hepatic portal vein. We hypothesized that when bilirubin levels are decreased, the urobilin increases in the plasma of obese humans, as compared to lean humans. To test this, we measured plasma levels of bilirubin and urobilin, …

Dysregulated Polycomb Repressive Complex 2 Contributes To Chronic Obstructive Pulmonary Disease By Rewiring Stem Cell Fate, Aria Byrd, Xufeng Qu, Alexsandr Lukyanchuk, Jinpeng Liu, Fan Chen, Kassandra J. Naughton, Tanner Ducote, Xiulong Song, Hannah Bowman, Yanming Zhao, Abigail R Edgin, Chi Wang, Jinze Liu, Christine Fillmore Brainson

Markey Cancer Center Faculty Publications

Aberrant lung cell differentiation is a hallmark of many lung diseases including chronic obstructive pulmonary disease (COPD). The EZH2-containing Polycomb Repressive Complex 2 (PRC2) regulates embryonic lung stem cell fate, but its role in adult lung is obscure. Histological analysis of patient tissues revealed that loss of PRC2 activity was correlated with aberrant bronchiolar cell differentiation in COPD lung. Histological and single-cell RNA-sequencing analyses showed that loss of EZH2 in mouse lung organoids led to lowered self- renewal capability, increased squamous morphological development, and marked shifts in progenitor cell populations. Evaluation of in vivo models revealed that heterozygosity of Ezh2 …

Extracellular Vesicle Distribution And Localization In Skeletal Muscle At Rest And Following Disuse Atrophy, Ahmed Ismaeel, Douglas W. Van Pelt, Zachary Hettinger, Xu Fu, Christopher I. Richards, Timothy A. Butterfield, Jonathan J. Petrocelli, Ivan J. Vechetti Jr., Amy L. Confides, Micah J. Drummond, Esther E. Dupont-Versteegden

Markey Cancer Center Faculty Publications

Background Skeletal muscle (SkM) is a large, secretory organ that produces and releases myokines that can have autocrine, paracrine, and endocrine effects. Whether extracellular vesicles (EVs) also play a role in the SkM adaptive response and ability to communicate with other tissues is not well understood. The purpose of this study was to investigate EV biogenesis factors, marker expression, and localization across cell types in the skeletal muscle. We also aimed to investigate whether EV concentrations are altered by disuse atrophy.

Methods To identify the potential markers of SkM‑derived EVs, EVs were isolated from rat serum using density gradient ultracentrifugation, …

Polycomb Deficiency Drives A Foxp2-High Aggressive State Targetable By Epigenetic Inhibitors, Fan Chen, Aria Byrd, Jinpeng Liu, Robert M. Flight, Tanner Ducote, Kassandra J. Naughton, Xiulong Song, Abigail R Edgin, Alexsandr Lukyanchuk, Danielle T. Dixon, Christian M. Gosser, Dave-Preston Esoe, Rani Jayswal, Stuart H. Orkin, Hunter N. B. Moseley, Chi Wang, Christine Fillmore Brainson

Markey Cancer Center Faculty Publications

Inhibitors of the Polycomb Repressive Complex 2 (PRC2) histone methyltransferase EZH2 are approved for certain cancers, but realizing their wider utility relies upon understanding PRC2 biology in each cancer system. Using a genetic model to delete Ezh2 in KRAS-driven lung adenocarcinomas, we observed that Ezh2 haplo-insufficient tumors were less lethal and lower grade than Ezh2 fully-insufficient tumors, which were poorly differentiated and metastatic. Using three-dimensional cultures and in vivo experiments, we determined that EZH2-deficient tumors were vulnerable to H3K27 demethylase or BET inhibitors. PRC2 loss/inhibition led to de-repression of FOXP2, a transcription factor that promotes migration and stemness, and FOXP2 …

Suppressing Hepatic Ugt1a1 Increases Plasma Bilirubin, Lowers Plasma Urobilin, Reorganizes Kinase Signaling Pathways And Lipid Species And Improves Fatty Liver Disease, Evelyn A. Bates, Zachary A. Kipp, Genesee J. Martinez, Olufunto O. Badmus, Mangala M. Soundarapandian, Donald Foster, Mei Xu, Justin F. Creeden, Jennifer R. Greer, Andrew J. Morris, David E. Stec, Terry D. Hinds Jr.

Markey Cancer Center Faculty Publications

Several population studies have observed lower serum bilirubin levels in patients with non-alcoholic fatty liver disease (NAFLD). Yet, treatments to target this metabolic phenotype have not been explored. Therefore, we designed an N-Acetylgalactosamine (GalNAc) labeled RNAi to target the enzyme that clears bilirubin from the blood, the UGT1A1 glucuronyl enzyme (GNUR). In this study, male C57BL/6J mice were fed a high-fat diet (HFD, 60%) for 30 weeks to induce NAFLD and were treated subcutaneously with GNUR or sham (CTRL) once weekly for six weeks while continuing the HFD. The results show that GNUR treatments significantly raised plasma bilirubin levels and …

The Link Between Intracellular Calcium Signaling And Exosomal Pd-L1 In Cancer Progression And Immunotherapy, Rakibul Alam, Mizanur Rahman, Zhiguo Li

Markey Cancer Center Faculty Publications

Exosomes are small membrane vesicles containing microRNA, RNA, DNA fragments, and proteins that are transferred from donor cells to recipient cells. Tumor cells release exo- somes to reprogram the factors associated with the tumor microenvironment (TME) causing tu- mor metastasis and immune escape. Emerging evidence revealed that cancer cell-derived exosomes carry immune inhibitory molecule program death ligand 1 (PD-L1) that binds with re- ceptor program death protein 1 (PD-1) and promote tumor progression by escaping immune response. Currently, some FDA-approved monoclonal antibodies are clinically used for cancer treatment by blocking PD-1/PD-L1 interaction. Despite notable treatment outcomes, some pa- tients show …

Xylazine Suppresses Fentanyl Consumption During Self-Administration And Induces A Unique Sex-Specific Withdrawal Syndrome That Is Not Altered By Naloxone In Rats, Shailesh N. Khatri, Safiyah M. Sadek, Percell T. Kendrick, Emma O. Bondy, Mei Hong, Sally Pauss, Dan Luo, Thomas E. Prisinzano, Kelly E. Dunn, Julie A. Marusich, Joshua S. Beckmann, Terry D. Hinds Jr., Cassandra D. Gipson

Markey Cancer Center Faculty Publications

Prescription and illicit opioid use are a public health crisis, with the landscape shifting to fentanyl use. Since fentanyl is 100-fold more potent than morphine, its use is associated with a higher risk of fatal overdose that can be remediated through naloxone (Narcan) administration. However, recent reports indicate that xylazine, an anesthetic, is increasingly detected in accidental fentanyl overdose deaths. Anecdotal reports suggest that xylazine may prolong the fentanyl “high,” alter the onset of fentanyl withdrawal, and increase resistance to naloxone-induced reversal of overdose. To date, no preclinical studies have evaluated the impacts of xylazine on fentanyl self-administration (SA; 2.5 …

Comparison Of Botanical Composition Methods And Change Over Time In Kentucky Pastures, Echo Elizabeth Gotsick

Theses and Dissertations--Plant and Soil Sciences

Botanical composition of pastures has been measured with numerous methods over the last century, but there have been limited direct comparisons between methods. The objective of this study was to compare botanical composition methods, to determine the most accurate and efficient method, and to access pasture composition change over time. Six farms with two pastures each were monitored across the state of Kentucky. Sampling occurred fall 2020 through fall 2022, three times a year using the following methods: step point, visual estimation, occupancy grid, and point quadrat (used as a reference method). The occupancy grid showed the highest similarity to …

To Determine The Role Of The Platelet Activating Factor - Receptor In Folfirinox Therapy-Mediated Microvesicles Particle Generation, Krishna Awasthi

Browse all Theses and Dissertations

Given that Pancreatic cancer continues to be one of the primary causes of cancer-related death and that existing treatment options have a poor success rate, it is important to investigate the role of potential factor(s) involved in pancreatic cancer growth or diminishing the effectiveness of chemotherapeutic agents. An alternative regimen for pancreatic cancer treatment called FOLFIRINOX has shown to increase the survival rate and improve Eastern Cooperative Oncology Group (ECOG) performance status score among the pancreatic cancer patients. However, FOLFIRINOX therapy is associated with several side effects. Through mechanisms involving the secretion of microvesicle particles (MVP), studies, including ours have …

Characterization Of Western Corn Rootworm (Coleoptera: Chrysomelidae) Susceptibility To Foliar Insecticides In Northeast Nebraska, Timothy B. Dang, Ana M. Vélez, Arnubio Valencia-Jiménez, Jordan Reinders, Emily E. Stricklin, Matthew W. Carroll, Clinton D. Pilcher, Jeffrey T. Krumm, Graham P. Head, Lance Meinke

Department of Entomology: Faculty Publications

Foliar-applied insecticides are commonly used for adult Western Corn Rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), control in Nebraska but little efficacy data is available. Anecdotal reports of reduced efficacy in areas of northeast Nebraska led to the conduct of this study. Objectives were to (i) evaluate the efficacy of commercial applications of commonly used formulated insecticides (bifenthrin, lambda-cyhalothrin, chlorpyrifos, or tank mixes) for WCR control in 7 northeast Nebraska counties during 2019 and 2020 and (ii) conduct adult WCR concentration-response vial bioassays with bifenthrin, chlorpyrifos, and dimethoate active ingredients on a subset of field populations. Whole plant counts …

Insect And Pest Management For Sustaining Crop Production Under Changing Climatic Patterns Of Drylands, Ruchika Kashyap, Sajjan Grover, Heena Puri, Sandeep Kaur, Jagmohan Singh, Karansher S. Sandhu, Gagandeep Kaur, Hinal Kharva, Shivreet Kaur, Balwinder Kaur

Department of Entomology: Faculty Publications

Climate change is alarming, particularly for agriculturists as it severely impacts the development, distribution, and survival of insects and pests, affecting crop production globally. Over time, climate change is drastically tumbling the crop productivity in all the cropping systems, whereas the dryland agriculture with existing low productivity is immensely hit. While all the existing species in drylands, including humans, are coping with extreme climate variations for millennia, future climate change predictions put dryland agriculture in a threat zone. Drylands support 38% of the world’s population; therefore, climate change coupled with population growth and global food security draws the attention of …

Teaching Forensic Entomology With Common Grocery Items: Decomposition And Insect Succession Studies, Erin Bauer, Charles Murrieta, Larry Barksdale

Department of Entomology: Faculty Publications

Forensic science and entomology programs may benefit from using deceased pigs as teaching resources due to anatomical similarities to humans. The use of such animals provides opportunities for students to learn the effects of geographical location and climate on insects; understand insect succession; practice insect collection and identification; and learn post-mortem interval procedures, taphonomic principles of decomposition, and crime scene investigation and management techniques. Forensic entomology and taphonomic studies fit well with educational interests in experiential learning. Pigs may be readily available through animal science departments or local producers, and many institutions may have property where this research can be …

Intercontinental Comparisons Of Subterranean Host-Parasite Communities Using Bipartite Network Analyses, Altangerel Tsogtsaikhan Dursahinhan, Sebastian Botero-Cañola, Scott L. Gardner

Scott L. Gardner Publications

Rodents living in a subterranean ecotope face a unique combination of evolutionary and ecological pressures and while host species evolution may be driven by the selective pressure from the parasites they harbour, the parasites may be responding to the selective pressures of the host. Here we obtained all available subterranean rodent host-parasite records from the literature and integrated these data by utilizing a bipartite network analysis to determine multiple critical parameters to quantify and measure the structure and interactions of the organisms present in host-parasite communities. A total of 163 species of subterranean rodent hosts, 174 parasite species, and 282 …

Host-Genetic-Based Outcome Of Co-Infection By Pcv2b And Prrsv In Pigs, Christian W. Eaton, Hiep Vu, Arabella L. Hodges, Seth P. Harris, Stephen D. Kachman, Daniel C. Ciobanu

School of Veterinary and Biomedical Sciences: Faculty Publications

Replication of porcine circovirus type 2 (PCV2), an important worldwide swine pathogen, has been demonstrated to be influenced by host genotype. Specifically, a missense DNA polymorphism (SYNGR2 p.Arg63Cys) within the SYNGR2 gene was demonstrated to contribute to variation in PCV2b viral load and subsequent immune response following infection. PCV2 is known to induce immunosuppression leading to an increase in susceptibility to subsequent infections with other viral pathogens such as porcine reproductive and respiratory syndrome virus (PRRSV). In order to assess the role of SYNGR2 p.Arg63Cys in co-infections, pigs homozygous for the favorable SYNGR2 p.63Cys (N = 30) …

Oligogalactolipid Production During Cold Challenge Is Conserved In Early Diverging Lineages, Allison C. Barnes, Jennifer L. Myers, Samantha M. Surber, Zhikai Liang, Jeffrey P. Mower, James Schnable, Rebecca Roston

Department of Biochemistry: Faculty Publications

Oligogalactolipid production is a response to severe cold in many land plant lineages. It occurs during times of membrane damage and can be reproduced in multiple species by cytosolic acidification.

Severe cold, defined as a damaging cold beyond acclimation temperatures, has unique responses, but the signaling and evolution of these responses are not well understood. Production of oligogalactolipids, which is triggered by cytosolic acidification in Arabidopsis (Arabidopsis thaliana), contributes to survival in severe cold. Here, we investigated oligogalactolipid production in species from bryophytes to angiosperms. Production of oligogalactolipids differed within each clade, suggesting multiple evolutionary origins of severe …

A Facile Strategy For The Fabrication Of Cell-Laden Porous Alginate Hydrogels Based On Two-Phase Aqueous Emulsions, Wen Xue, Donghee Lee, Yunfan Kong, Mitchell Kuss, Ying Huang, Taesung Kim, Soonkyu Chung, Andrew T. Dudley, Seung-Hyun Ro, Bin Duan

Department of Biochemistry: Faculty Publications

Porous alginate (Alg) hydrogels possess many advantages as cell carriers. However, current pore generation methods require either complex or harsh fabrication processes, toxic components, or extra purification steps, limiting the feasibility and affecting the cellular survival and function. In this study, a simple and cell-friendly approach to generate highly porous cell-laden Alg hydrogels based on two-phase aqueous emulsions is reported. The pre-gel solutions, which contain two immiscible aqueous phases of Alg and caseinate (Cas), are cross-linked by calcium ions. The porous structure of the hydrogel construct is formed by subsequently removing the Cas phase from the ion-cross-linked Alg hydrogel. Those …

Conformal Electrodeposition Of Antimicrobial Hydrogels Formed By Self-Assembled Peptide Amphiphiles, Gervasio Zaldivar, Jiachen Feng, Leonardo Lizarraga, Yafan Yu, Luana De Campos, Kelly Mari Pires De Oliveira, Kurt Piepenbrink, Martin Conda-Sheridan, Mario Tagliazucchi

Department of Biochemistry: Faculty Publications

The colonization of biomedical surfaces by bacterial biofilms is concerning because these microorganisms display higher antimicrobial resistance in biofilms than in liquid cultures. Developing antimicrobial coatings that can be easily applied to medically-relevant complex-shaped objects, such as implants and surgical instruments, is an important and challenging research direction. This work reports the preparation of antibacterial surfaces via the electrodeposition of a conformal hydrogel of self-assembling cationic peptide-amphiphiles (PAs). Hydrogels of three PAs are electrodeposited: C₁₆K₂, C₁₆K₃, and C₁₈K₂, where C_n is an alkyl chain of n methylene …

Impact Of Eastern Redcedar Encroachment On Water Resources In The Nebraska Sandhills, Yaser Kishawi, Aaron R. Mittelstet, Troy E. Gilmore, Dirac Twidwell, Tirthankar Roy, Nawaraj Shrestha

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Worldwide, tree or shrub dominated woodlands have encroached into herbaceous dominated grasslands. While very few studies have evaluated the impact of Eastern Redcedar (redcedar) encroachment on the water budget, none have analyzed the impact on water quality. In this study, we evaluated the impact of redcedar encroachment on the water budget in the Nebraska Sand Hills and how the decreased streamflow would increase nitrate and atrazine concentrations in the Platte River. We calibrated a Soil and Water Assessment Tool (SWAT model) for streamflow, recharge, and evapotranspiration. Using a moving window with a dilate morphological filter, encroachment scenarios of 11.9%, 16.1%, …

A Graduate-Level Field Course In Irrigation And Agricultural Water Management For An Immersive Learning Experience, Derek M. Heeren, László G. Hayde, Dean Eisenhauer, Peter G. Mccornick, Ali T. Mohammed, Aaron R. Mittelstet, Alan L. Boldt, Xin Qiao, David Mabie, Francisco Muñoz-Arriola

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Effective irrigation and agricultural water management (IAWM) is critical for food security and water security. A key requirement in designing, implementing and operation of IWM is the necessary knowledge and capacity on the farm, in the service industry and within the supply chain. Educational opportunities that not only teach the relevant principles of irrigated agriculture, but also the necessary applied skills are essential. An Irrigation Field Course was initiated by the IHE Delft Institute for Water Education (IHE Delft) and was later developed as a joint field course with IHE Delft, the University of Nebraska-Lincoln (UNL), and the Daugherty Water …

Estimating Battery Size Requirements For Tractor Electrification Of Row-Crop Planting Operations, Cheetown Liew, Andrew Donesky, Mark Freyhof, Ian Tempelmeyer, Santosh Kumar Pitla

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Power sources such as batteries, used for both on-road and off-road vehicles, are advancing at a rapid pace. Electric batteries are becoming more power dense, thus allowing them to be used as a power source to replace previous diesel or gasoline-powered systems. Efforts are underway to transition off-road agricultural vehicles from Internal Combustion Engine (ICE) vehicles to electric vehicles (EVs); however, the energy requirements of typical agricultural field operations need to be fully understood before such a transition can occur. Theoretical prediction equations available in the American Society of Agricultural and Biological Engineers (ASABE) standards or the use of engine …

Stochasticity Directs Adaptive Evolution Toward Nonequilibrium Evolutionary Attractors, John Delong, Clayton E. Cressler

School of Biological Sciences: Faculty Publications

Stochastic processes such as genetic drift may hinder adaptation, but the effect of such stochasticity on evolution via its effect on ecological dynamics is poorly understood. Here we evaluate patterns of adaptation in a population subject to variation in demographic stochasticity. We show that stochasticity can alter population dynamics and lead to evolutionary outcomes that are not predicted by classic eco-evolutionary modeling approaches. We also show, however, that these outcomes are governed by nonequilibrium evolutionary attractors— these are maxima in lifetime reproductive success when stochasticity keeps the ecological system away from the deterministic equilibrium. These NEEAs alter the path of …

The Consumption Of Viruses Returns Energy To Food Chains, John Delong, James L. Van Etten, Zeina Al-Ameeli, Irina Agarkova, David Dunigan

School of Biological Sciences: Faculty Publications

Viruses impact host cells and have indirect effects on ecosystem processes. Plankton such as ciliates can reduce the abundance of virions in water, but whether virus consumption translates into demographic consequences for the grazers is unknown. Here, we show that small protists not only can consume viruses they also can grow and divide given only viruses to eat. Moreover, the ciliate Halteria sp. foraging on chloroviruses displays dynamics and interaction parameters that are similar to other microbial trophic interactions. These results suggest that the effect of viruses on ecosystems extends beyond (and in contrast to) the viral shunt by redirecting …

Pathways Of Density Dependence And Natural Selection In Modern Humans, John Delong

School of Biological Sciences: Faculty Publications

Living things depend on a flow of energy and materials to grow, reproduce, and maintain their bodies. Populations are aggregations of individuals, so they too depend on resources. Humans use many fuels derived from the Earth’s photosynthetic energy, which in turn support a population that often occurs at unusually high densities for a mammal. Like most populations, growing human populations may experience negative feedbacks from population size unless the socio-economic system in which the population lives grows fast enough to maintain resource flows to individuals and to limit the downsides of high density. I map out a simple view of …