Biology Commons^™

Behavioral Plasticity Across Non-Social Contexts In Female Green Swordtails, Xiphophorus Helleri, Lindsey M. Coit

School of Biological Sciences: Dissertations, Theses, and Student Research

Phenotypic plasticity is the ability of an individual to alter its phenotype in response to environmental change. Individuals that express plasticity in behavior can quickly respond to changes that occur in the environment. Therefore, individuals that exhibit behavioral plasticity can alter their behavioral expression to best match current environmental conditions. The degree and direction of behavioral plasticity may be influenced by variation in individual characteristics. Understanding how variation in individual traits affects behavioral plasticity, and, whether patterns of behavioral plasticity are consistent across behavioral contexts are important topics to explore as we try to better understand how plasticity evolves and …

Variation In Density Dependent Seedling Survival Across Forests Of Different Successional Age And Hunting Protection Status, Nohemi Huanca-Nunez

School of Biological Sciences: Dissertations, Theses, and Student Research

Over 50% of the original extent of tropical forests has been cleared. Restoration of secondary forests is important for maintaining the ecosystem services that mature tropical forests provide. Density dependence (DD) is thought to be a major mechanism for shaping forest community structure and may cause reduced spatial aggregation among individuals of the same species, allowing for maintenance of diversity. While much research has focused on DD in mature tropical forests, few studies have examined how DD may influence community structure in secondary forests, many of which are also exposed to hunting. There are several important agents of negative and …

Development Of Site Fidelity In The Nocturnal Amblypygid, Phrynus Marginemaculatus, Jacob M. Graving, Verner P. Bingman, Eileen Hebets, Daniel D. Wiegmann

Eileen Hebets Publications

Amblypygids are capable of navigation in the complex terrain of rainforests in near complete darkness. Path integration is unnecessary for successful homing, and the alternative mechanisms by which they navigate have yet to be elucidated. Here, our aims were to determine whether the amblypygid Phrynus marginemaculatus could be trained to reliably return to a target shelter in a laboratory arena—indicating goal recognition—and to document changes in behavior associated with the development of fidelity. We recorded nocturnal movements and space use by individuals over five nights in an arena in which subjects were provided with two shelters that differed in quality. …

Unexpected Nongenetic Individual Heterogeneity And Trait Covariance In Daphnia And Its Consequences For Ecological And Evolutionary Dynamics, Clayton E. Cressler, Stefan Bengtson, William A. Nelson

School of Biological Sciences: Faculty Publications

Individual differences in genetics, age, or environment can cause tremendous differences in individual life-history traits. This individual heterogeneity generates demographic heterogeneity at the population level, which is predicted to have a strong impact on both ecological and evolutionary dynamics. However, we know surprisingly little about the sources of individual heterogeneity for particular taxa or how different sources scale up to impact ecological and evolutionary dynamics. Here we experimentally study the individual heterogeneity that emerges from both genetic and nongenetic sources in a species of freshwater zooplankton across a large gradient of food quality. Despite the tight control of environment, we …

Genetic Code Expansion In Biochemical Investigations And Biomedical Applications, Nanxi Wang

Department of Chemistry: Dissertations, Theses, and Student Research

Genetic code expansion provides a powerful tool for site-specific incorporation of unnatural amino acids (unAAs) with novel biochemical and physiological properties into proteins in live cells and organisms. To achieve this, a nonsense codon suppression system, which consists of an orthogonal aminoacyl-tRNA synthetase (aaRS) and tRNA pair that specifically decodes a nonsense codon (e.g., amber codon and quadruplet codon) with an unAA but do not “cross talk” with their endogenous counterparts, was established. This Ph.D. thesis presents our efforts on evolution and application of nonsense codon suppression systems for biochemical and biomedical investigations.

In Chapter 1, a brief overview of …

Hitching A Ride: First Record Of A Least Chipmunk (Tamias Minimus) In Eastern Nebraska, Keith Geluso, Michael L. Forsberg

Transactions of the Nebraska Academy of Sciences and Affiliated Societies

On 10 October 2016, a Least Chipmunk (Tamias minimus) was discovered in a residential area of Lincoln, Lancaster County, Nebraska. The closest populations of Least Chipmunks reside > 640 km to the west in northwestern Nebraska and southeastern Wyoming. The most parsimonious explanation for this unusual observation is that the chipmunk was transported to the city by humans. A likely scenario is that the chipmunk hitched a ride to Lincoln in a motor vehicle on 2 October 2016, when one of us drove 1500 km in a single day from Jackson, Teton County, Wyoming, after residing in that area …

Biotic And Abiotic Factors Predicting The Global Distribution And Population Density Of An Invasive Large Mammal, Jesse S. Lewis, Mathew L. Farnsworth, Christopher L. Burdett, David M. Theobald, Miranda Gray, Ryan S. Miller

Other Publications in Wildlife Management

Biotic and abiotic factors are increasingly acknowledged to synergistically shape broad-scale species distributions. However, the relative importance of biotic and abiotic factors in predicting species distributions is unclear. In particular, biotic factors, such as predation and vegetation, including those resulting from anthropogenic land-use change, are underrepresented in species distribution modeling, but could improve model predictions. Using generalized linear models and model selection techniques, we used 129 estimates of population density of wild pigs (Sus scrofa) from 5 continents to evaluate the relative importance, magnitude, and direction of biotic and abiotic factors in predicting population density of an invasive large mammal …

The Combined Effects Of Reactant Kinetics And Enzyme Stability Explain The Temperature Dependence Of Metabolic Rates, John Delong, J. P. Gibert, Thomas M. Luhring, Gwendolyn C. Bachman, B. Reed, A. Neyer, Kristi Montooth

School of Biological Sciences: Faculty Publications

A mechanistic understanding of the response of metabolic rate to temperature is essential for understanding thermal ecology and metabolic adaptation. Although the Arrhenius equation has been used to describe the effects of temperature on reaction rates and metabolic traits, it does not adequately describe two aspects of the thermal performance curve (TPC) for metabolic rate—that metabolic rate is a unimodal function of temperature often with maximal values in the biologically relevant temperature range and that activation energies are temperature dependent. We show that the temperature dependence of metabolic rate in ectotherms is well described by an enzyme-assisted Arrhenius (EAAR) model …

Microbial Strains And Methods Of Making And Using, Nicole Roswitha Buan Murphy, Jennifer Catlett

School of Biological Sciences: Faculty Publications

Microbial strains are provided, as are methods of making and using such microbial strains.

Methane is an increasingly important global energy Source, both as the primary component of natural gas and as a biologically produced fuel. Currently, Sweden uses 100% renewable methane (biogas) in place of compressed natural gas (CNG) for transportation fuel, and several European countries are implementing policies to increase their pro portion of biogas transportation fuel. In addition, methane is a valuable chemical for conversion into other higher-order carbon compounds (e.g., methanol, formate, alkanes, ter penes). More than 50% of the world's methane is produced biologically by …

Testing The Terminal Investment Hypothesis In California Oaks, Walter D. Koenig, Johannes M.H. Knops, William J. Carmen, Mario B. Pesendorfer

School of Biological Sciences: Faculty Publications

The terminal investment hypothesis—which proposes that reproductive investment should increase with age-related declines in reproductive value—has garnered support in a range of animal species but has not been previously examined in long-lived plants, such as trees. We tested this hypothesis by comparing relative acorn production and radial growth among 1,0001 mature individuals of eight species of California oaks (genus Quercus) followed for up to 37 years, during which time 70 trees died apparently natural deaths. We found no significant differences in the radial growth, acorn production, or index of reproductive effort, taking into consideration both growth and reproduction among dying …

Ecological Pleiotropy Suppresses The Dynamic Feedback Generated By A Rapidly Changing Trait, John Delong

School of Biological Sciences: Faculty Publications

Population dynamics may carry a signature of an ecology- evolution-ecology feedback, known as eco-evolutionary dynamics, when functionally important traits change. Given current theory, the absence of a feedback from a trait with strong links to species interactions should not occur. In a previous study with the Didinium-Paramecium predator-prey system, however, rapid and large-magnitude changes in predator cell volume occurred without any noticeable effect on the population dynamics. Here I resolve this theory-data conflict by showing that ecological pleiotropy—when a trait has more than one functional effect on an ecological process—suppresses shifts in dynamics that would arise, given the links between …

Contribution Of Pentose Catabolism To Molecular Hydrogen Formation By Targeted Disruption Of Arabinose Isomerase (Araa) In The Hyperthermophilic Bacterium Thermotoga Maritima, Derrick White, Raghuveer Singh, Deepak Rudrappa, Jackie Mateo, Levi Kramer, Laura Freese, Paul H. Blum

School of Biological Sciences: Faculty Publications

Thermotoga maritima ferments a broad range of sugars to form acetate, carbon dioxide, traces of lactate, and near theoretic yields of molecular hydrogen (H₂). In this organism, the catabolism of pentose sugars such as arabinose depends on the interaction of the pentose phosphate pathway with the Embden-Myerhoff and Entner-Doudoroff pathways. Although the values for H₂ yield have been determined using pentose-supplemented complex medium and predicted by metabolic pathway reconstruction, the actual effect of pathway elimination on hydrogen production has not been reported due to the lack of a genetic method for the creation of targeted mutations. Here, …

Cognition-Mediated Evolution Of Low-Quality Floral Nectars, Vladislav Nachev, Kai Petra Stich, Clemens Winter, Alan B. Bond, Alan Kamil, York Winter

Alan Bond Publications

Plants pollinated by hummingbirds or bats produce dilute nectars even though these animals prefer more concentrated sugar solutions. This mismatch is an unsolved evolutionary paradox. Here we show that lower quality, or more dilute, nectars evolve when the strength of preferring larger quantities or higher qualities of nectar diminishes as magnitudes of the physical stimuli increase. In a virtual evolution experiment conducted in the tropical rainforest, bats visited computer-automated flowers with simulated genomes that evolved relatively dilute nectars. Simulations replicated this evolution only when value functions, which relate the physical stimuli to subjective sensations, were nonlinear. Selection also depended on …

Neural Circuitry For Target Selection And Action Selection In Animal Behavior, Daizaburo Shizuka, Eileen Hebets, Kim L. Hoke

Papers in Behavior in Biological Sciences

Animal behaviorists have long strived for a comprehensive understanding of the proximate and ultimate causes of complex behavior, and we propose that recent advances in neurobiology can help reshape or clarify this behavior-oriented understanding. We begin with an overview of current views of neural circuit mechanisms that mediate target selection and action selection. In target selection, different stimuli compete for priority in sensory-motor process- ing. Action selection is the process by which multiple possible motor actions compete for priority in a manner which balances the needs of the animal with opportunities or threats in the environment. We next discuss spatial …

Cooperative Processing Of Primary Mirnas By Dus16 And Dcl3 In The Unicellular Green Alga Chlamydomonas Reinhardtii, Tomohito Yamasaki, Heriberto D. Cerutti

School of Biological Sciences: Faculty Publications

We have previously reported that the RNA-binding protein Dull slicer 16 (DUS16) plays a key role in the processing of primary miRNAs (pri-miRNAs) in the unicellular green alga Chlamydomonas reinhardtii. In the present report, we elaborate on the interaction of DUS16 with Dicer-like 3 (DCL3) during pri-miRNA processing. Comprehensive analyses of small RNA libraries derived from mutant and wild-type algal strains allowed the de novo prediction of 35 pri-miRNA genes, including 9 previously unknown ones. The pri-miRNAs dependent on DUS16 for processing largely overlapped with those dependent on DCL3. Our findings suggest that DUS16 and DCL3 work cooperatively, presumably …

Host Allometry Influences The Evolution Of Parasite Host-Generalism: Theory And Meta-Analysis, Josephine G. Walker, Amy Hurford, Jo Cable, Amy R. Ellison, Stephen J. Price, Clayton E. Cressler

School of Biological Sciences: Faculty Publications

Parasites vary widely in the diversity of hosts they infect: some parasite species are specialists—infecting just a single host species, while others are generalists, capable of infecting many. Understanding the factors that drive parasite host-generalism is of basic biological interest, but also directly relevant to predicting disease emergence in new host species, identifying parasites that are likely to have unidentified additional hosts, and assessing transmission risk. Here, we use mathematical models to investigate how variation in host body size and environmental temperature affect the evolution of parasite host-generalism. We predict that parasites are more likely to evolve a generalist strategy …

Host Allometry Influences The Evolution Of Parasite Host-Generalism: Theory And Meta-Analysis, Josephine G. Walker, Amy Hurford, Jo Cable, Amy R. Ellison, Stephen J. Price, Clayton E. Cressler

School of Biological Sciences: Faculty Publications

Parasites vary widely in the diversity of hosts they infect: some parasite species are specialists—infecting just a single host species, while others are generalists, capable of infecting many. Understanding the factors that drive parasite host-generalism is of basic biological interest, but also directly relevant to predicting disease emergence in new host species, identifying parasites that are likely to have unidentified additional hosts, and assessing transmission risk. Here, we use mathematical models to investigate how variation in host body size and environmental temperature affect the evolution of parasite host-generalism. We predict that parasites are more likely to evolve a generalist strategy …

Distinct Transcriptome Profiles Of Gag-Specific Cd8+ T Cells Temporally Correlated With The Protection Elicited By Sivδnef Live Attenuated Vaccine, Wuxun Lu, Yanmin Wan, Fangrui Ma, R. Paul Johnson, Qingsheng Li

School of Biological Sciences: Faculty Publications

The live attenuated vaccine (LAV) SIVmac239Δnef (SIVΔnef) confers the best protection among all the vaccine modalities tested in rhesus macaque model of HIV-1 infection. This vaccine has a unique feature of time-dependent protection: macaques are not protected at 3±5 weeks post vaccination (WPV), whereas immune protection emerges between 15 and 20 WPV. Although the exact mechanisms of the time-dependent protection remain incompletely understood, studies suggested that both cellular and humoral immunities contribute to this time-dependent protection. To further elucidate the mechanisms of protection induced by SIVΔnef, we longitudinally compared the global gene expression profiles of SIV Gag-CM9+ CD8+ (Gag-specific CD8+) …

Sensory System Plasticity In A Visually Specialized, Nocturnal Spider, Jay A. Stafstrom, Peter Michalik, Eileen Hebets

School of Biological Sciences: Faculty Publications

The interplay between an animal’s environmental niche and its behavior can influence the evolutionary form and function of its sensory systems. While intraspecific variation in sensory systems has been documented across distant taxa, fewer studies have investigated how changes in behavior might relate to plasticity in sensory systems across developmental time. To investigate the relationships among behavior, peripheral sensory structures, and central processing regions in the brain, we take advantage of a dramatic within-species shift of behavior in a nocturnal, net-casting spider (Deinopis spinosa), where males cease visually-mediated foraging upon maturation. We compared eye diameters and brain region volumes across …

The Economic Value Of Grassland Species For Carbon Storage, Bruce A. Hungate, Edward B. Barbier, Amy W. Ando, Samuel P. Marks, Peter B. Reich, Natasja Van Gestel, David Tilman, Johannes M. H. Knops, David U. Hooper, Bradley J. Butterfield, Bradley J. Cardinale

School of Biological Sciences: Faculty Publications

Carbon storage by ecosystems is valuable for climate protection. Biodiversity conservation may help increase carbon storage, but the value of this influence has been difficult to assess. We use plant, soil, and ecosystem carbon storage data from two grassland biodiversity experiments to show that greater species richness increases economic value: Increasing species richness from 1 to 10 had twice the economic value of increasing species richness from 1 to 2. The marginal value of each additional species declined as species accumulated, reflecting the nonlinear relationship between species richness and plant biomass production. Our demonstration of the economic value of biodiversity …

Increased Productivity In Wet Years Drives A Decline In Ecosystem Stability With Nitrogen Additions In Arid Grasslands, Junfeng Wang, Johannes M.H. Knops, Chad E. Brassil, Chunsheng Mu

School of Biological Sciences: Faculty Publications

Adding nutrients to nutrient-limited ecosystems typically lowers plant diversity and decreases species asynchrony. Both, in turn, decrease the stability of productivity in the response to negative climate fluctuations such as droughts. However, most classic studies examining stability have been done in relatively wet grasslands dominated by perennial grasses. We examined how nutrient additions influence the stability of productivity to rainfall variability in an arid grassland with a mix of perennial and annual species. Of the nutrients, only nitrogen increased productivity, and only in wet years. In addition, only nitrogen decreased the stability of productivity. Thus, nutrient addition makes ecosystem productivity …

Glaciation As A Migratory Switch, Robert M. Zink, Aubrey S. Gardner

School of Biological Sciences: Faculty Publications

Migratory behavior in birds is evolutionarily plastic, but it is unclear how this behavior responded during glacial cycles. One view is that at glacial maxima, species simply shifted their breeding ranges south of glacial ice and remained migratory. To test this hypothesis, we constructed ecological niche models for breeding and wintering ranges of 56 species, finding that 70% of currently long-distance North American migrant species likely lacked suitable breeding habitat in North America at the Last Glacial Maximum (LGM), and we hypothesized that they reverted to the ancestral state of being tropical sedentary residents. A smaller percentage of short-distance migrants …

Increased Insertion Number Leads To Increased Sperm Transfer And Fertilization Success In A Nursery Web Spider, Alissa G. Anderson, Eileen Hebets

Eileen Hebets Publications

Across animals, a male's fitness is largely dictated by his ability to fertilize eggs; and there exists a plethora of male adaptations associated with increasing fertilization success. In the nursery web spider, Pisaurina mira, males restrain females prior to and during copulation by wrapping them with silk. Previous research demonstrates that copulatory silk wrapping reduces a male's chance of being sexually cannibalized and increases the number of sperm transfer opportunities (termed insertions) that a male can achieve within a mating. While avoiding cannibalism provides an obvious survival benefit to males, the impact of insertion number on male fitness remains …

Importance Of The Antenniform Legs, But Not Vision, For Homing By The Neotropical Whip Spider Paraphrynus Laevifrons, Verner P. Bingman, Jacob M. Graving, Eileen Hebets, Daniel D. Wiegmann

Eileen Hebets Publications

Amblypygids, or whip spiders, are nocturnal, predatory arthropods that display a robust ability to navigate to their home refuge. Prior field observations and displacement studies in amblypygids demonstrated an ability to home from distances as far away as 10 m. In the current study, micro-transmitters were used to take morning position fixes of individual Paraphrynus laevifrons following an experimental displacement of 10 m from their home refuge. The intention was to assess the relative importance of vision compared with sensory input acquired from the antenniform legs for navigation as well as other aspects of their spatial behavior. Displaced individuals were …

Measurement Instrument For Scientific Teaching (Mist): A Tool To Measure The Frequencies Of Research-Based Teaching Practices In Undergraduate Science Courses, Mary F. Durham, Jennifer K. Knight, Brian A. Couch

School of Biological Sciences: Faculty Publications

The Scientific Teaching (ST) pedagogical framework provides various approaches for science instructors to teach in a way that more closely emulates how science is practiced by actively and inclusively engaging students in their own learning and by making instructional decisions based on student performance data. Fully understanding the impact of ST requires having mechanisms to quantify its implementation. While many useful instruments exist to document teaching practices, these instruments only partially align with the range of practices specified by ST, as described in a recently published taxonomy. Here, we describe the development, validation, and implementation of the Measurement Instrument for …

Student Buy-In Toward Formative Assessments: The Influence Of Student Factors And Importance For Course Success, Kathleen R. Brazeal, Brian A. Couch

School of Biological Sciences: Faculty Publications

Formative assessment (FA) techniques, such as pre-class assignments, in-class activities, and post-class homework, have been shown to improve student learning. While many students find these techniques beneficial, some students may not understand how they support learning or may resist their implementation. Improving our understanding of FA buy-in has important implications, since buy-in can potentially affect whether students fully engage with and learn from FAs. We investigated FAs in 12 undergraduate biology courses to understand which student characteristics influenced buy-in toward FAs and whether FA buy-in predicted course success. We administered a mid-semester survey that probed student perceptions toward several different …

Sigma Virus (Dmelsv) Incidence In Lines Of Drosophila Melanogaster Selected For Survival Following Infection With Bacillus Cereus, Meghan L. Bentz, Eve A. Humphrey, Lawrence G. Harshman

School of Biological Sciences: Faculty Publications

The immune response of Drosophila melanogaster is complex and involves both specific and general responses to parasites. In this study we tested for cross-immunity for bacteria and viruses by scoring the incidence of infection with the vertically transmitted Sigma virus (DMelSV) in the progeny of a cross between females transmitting DMelSV at high frequencies and males from lines subjected to three selection regimes related to resistance to Bacillus cereus. There was no significant difference in transmission of DMelSV among selection regimes, though results suggest that the B. cereus selected lines had lower rates of infection by DMelSV. We found …

Record Breaking Achievements By Spiders And The Scientists Who Study Them, Stefano Mammola, Peter Michalik, Eileen Hebets, Marco Isaia

Eileen Hebets Publications

Organismal biology has been steadily losing fashion in both formal education and scientific research. Simultaneous with this is an observable decrease in the connection between humans, their environment, and the organisms with which they share the planet. Nonetheless, we propose that organismal biology can facilitate scientific observation, discovery, research, and engagement, especially when the organisms of focus are ubiquitous and charismatic animals such as spiders. Despite being often feared, spiders are mysterious and intriguing, offering a useful foundation for the effective teaching and learning of scientific concepts and processes. In order to provide an entryway for teachers and students—as well …

Cumulative Herbivory Outpaces Compensation For Early Floral Damage On A Monocarpic Perennial Thistle, Natalie M. West, Svata M. Louda

School of Biological Sciences: Faculty Publications

Floral herbivory represents a major threat to plant reproductive success, driving the importance of plant tolerance mechanisms that minimize fitness costs. However, the cumulative insect herbivory plants experience under natural conditions complicates predictions about tolerance contributions to net fitness. Apical damage can lead to compensatory seed production from late season flowering that ameliorates early season fitness losses. Yet, the compensation realized depends on successful development and herbivore escape by later season flowers. Using monocarpic perennial Cirsium canescens, we quantified seed-reproductive fitness of plants with vs. without experimental damage to the early-developing large apical flower head, with and without a …

Nematodes Associated With Mammals In The Great American Biotic Interchange (Gabi), F. Agustin Jimenez, Juliana Notarnicola, Scott Lyell Gardner

Scott L. Gardner Publications

The Great American Biotic Interchange (GABI) is a large-scale zoogeographic event that illustrates the exchange and diversification of mammals between North and South America. This phenomenon was accelerated by the connection of both landmasses during the Pliocene. Support for this phenomenon includes the extant distribution of xenarthrans, didelphiomorph marsupials, hystricognath and cricetine rodents, sciurids and carnivores, as well as the distribution of fossils in the stratigraphic record and the coalescence of genotypes. Contrasting with the relatively well-documented role and history of mammals in GABI, the role of their parasites has been largely neglected. As a consequence, the reconstructions of the …