Life Sciences Commons^™

Vertebrate Body Size Jumps The Wright Way, Peter J. Wagner

School of Biological Sciences: Faculty Publications

Fossil data provide copious evidence that anatomical (morphological) change within individual lineages is not constant: short bursts of great change commonly separate long durations of little change (1, 2). Despite this, most models of morphological change assume that probabilities of morphological character change are the same from one generation to the next: even if rates change over time—such as in “Cambrian explosion” or “early burst” models, where high disparity among anatomies evolves early—then it is still assumed that fast rates of continuous character change gave way to slow rates of continuous change (3). In statistical parlance, early bursts usually are …

Nitrogen Addition And Ecosystem Functioning: Both Species Abundances And Traits Alter Community Structure And Function, Anna R. Tatarko, Johannes M.H. Knops

School of Biological Sciences: Faculty Publications

Increased nutrient inputs can cause shifts in plant community composition and plant functional traits, both of which affect ecosystem function. We studied community- and species-level leaf functional trait changes in a full factorial nitrogen (N), phosphorus (P), and potassium (K) fertilization experiment in a semi-arid grassland. Nitrogen was the only nutrient addition to significantly affect leaf functional traits, and N addition increased community-weighted specific leaf area (SLA) by 19%, leaf chlorophyll content by 34%, height by 26%, and leaf dry matter content (LDMC) decreased by 11% while leaf thickness and toughness did not change significantly. At the species level, most …

American Society Of Parasitologists Newsletter, Volume 39, Number 2, Fall/ Winter, 2017, Scott L. Gardner

American Society of Parasitologists: Newsletter

Fall/Winter 2017 issue of the ASP newsletter.

Small Rna-Dependent Gene Silencing In The Green Alga Chlamydomonas Reinhardtii: Functions And Mechanisms, Eun Jeong Kim

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

Small RNAs (sRNAs), ~20-30 nucleotides in length, are non-coding RNAs that play essential roles in the regulation of gene expression in eukaryotes. They lead to inactivation of cognate sequences at the post-transcriptional level via a variety of mechanisms involved in translation inhibition and/or RNA degradation.

In the Chlorophyta Chlamydomonas reinhardtii, however, the molecular machinery responsible for sRNA-mediated translational repression remains unclear. To address the mechanisms of translation inhibition by sRNA, we have isolated an RNAi defective mutant (Mut26), which contains a deletion of the gene encoding the homolog of CCR4 in Chlamydomonas. We investigated the expression of …

Multiple Hypotheses Explain Variation In Extra-Pair Paternity At Different Levels In A Single Bird Family, Lyanne Brouwer, Martijn Van De Pol, Nataly Hidalgo Aranzamendi, Glen Bain, Daniel T. Baldassarre, Lesley C. Brooker, Michael G. Brooker, Diane Diane Colombelli-Négrel, Erik Enbody, Kurt Gielow, Michelle L. Hall, Allison E. Johnson, Jordan Karubian, Sjouke A. Kingma, Sonia Kleindorfer, Marina Louter, Raoul A. Mulder, Anne Peters, Stephen Pruett-Jones, Keith A. Tarvin, Derrick J. Thrasher, Claire W. Varian-Ramos, Michael S. Webster, Andrew Cockburn

School of Biological Sciences: Faculty Publications

Extra-pair paternity (EPP), where offspring are sired by a male other than the social male, varies enormously both within and among species. Trying to explain this variation has proved difficult because the majority of the interspecific variation is phylogenetically based. Ideally, variation in EPP should be investigated in closely related species, but clades with sufficient variation are rare. We present a comprehensive multifactorial test to explain variation in EPP among individuals in 20 populations of nine species over 89 years from a single bird family (Maluridae). Females had higher EPP in the presence of more helpers, more neighbors or …

The North American Quails, Partridges, And Pheasants, Paul A. Johnsgard

Zea E-Books Collection

This book documents the biology of six species of New World quails that are native to North America north of Mexico (mountain, scaled, Gambel’s, California, and Montezuma quails, and the northern bobwhite), three introduced Old World partridges (chukar, Himalayan snowcock, and gray partridge), and the introduced common (ring-necked) pheasant. Collectively, quails, partridges, and pheasants range throughout all of the continental United States and the Canadian provinces. Two of the species, the northern bobwhite and ring-necked pheasant, are the most economically important of all North American upland game birds. All of the species are hunted extensively for sport and are highly …

Field Evidence Challenges The Often-Presumed Relationship Between Early Male Maturation And Female-Biased Sexual Size Dimorphism, Marie Claire Chelini, Eileen Hebets

Eileen Hebets Publications

Female-biased sexual size dimorphism (SSD) is often considered an epiphenomenon of selection for the increased mating opportunities provided by early male maturation (i.e., protandry). Empirical evidence of the adaptive significance of protandry remains nonetheless fairly scarce. We use field data collected throughout the reproductive season of an SSD crab spider, Mecaphesa celer, to test two hypotheses: Protandry provides fitness benefits to males, leading to female-biased SSD, or protandry is an indirect consequence of selection for small male size/large female size. Using field-collected data, we modeled the probability of mating success for females and males according to their timing of …

Phosphate Starvation Induces Replacement Of Phospholipids With The Betaine Lipid Diacylglycerol-N,N,N-Trimethylhomoserine In The Human Fungal Pathogen Candida Albicans, Surabhi Naik, Rebecca E. Cahoon, Bridget Tripp, Christian Elowsky, Sophie Alvarez, Kan Liu, Chi Zhang, Wayne R. Riekhof

School of Biological Sciences: Faculty Publications

We have previously demonstrated that phosphate starvation induces replacement of phosphatidylcholine with the betaine lipid diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) in fungi. In Neurospora crassa, the BTA1 gene encodes the betaine lipid synthase, which is necessary and sufficient for DGTS synthesis. BTA1 expression and DGTS accumulation are part of the fungal phosphorus (P_i) deprivation (PHO) regulon, mediated by the NUC-1/Pho4p transcription factor. We now demonstrate that the human pathogen Candida albicans encodes a BTA1 ortholog (CaBTA1), which is activated during P_i scarcity. The CaBTA1 gene is also induced under certain biofilm-promoting conditions independent of P …

Characterization Of A Novel Mitochondrial Plasmid In Brassica, Mackenzie Strehle

UCARE Research Products

Possessing some of the largest and most complex genomes of any eukaryotic organelles, plant mitochondria are notorious for their rapidly rearranging genetic framework. In addition to containing a large and complex mitochondrial genome, the mitochondria of several plants in the genus Brassica have also been shown to contain an independent, self-replicating linear plasmid. Interestingly, the plasmid appears to be able to move independently between the cytoplasm and the mitochondria, and it can be paternally inherited, unlike the rest of the mitochondrial genome. The plasmid also has features similar to those of adenoviruses, including terminal inverted repeats and covalently bound proteins …

Multiple Streptomyces Species With Distinct Secondary Metabolomes Have Identical 16s Rrna Gene Sequences, Sanjay Antony-Babu, Didier Stien, Véronique Eparvier, Delphine Parrot, Sophie Tomasi, Marcelino Suzuki

School of Biological Sciences: Faculty Publications

Microbial diversity studies using small subunit (SSU) rRNA gene sequences continue to advance our understanding of biological and ecological systems. Although a good predictor of overall diversity, using this gene to infer the presence of a species in a sample is more controversial. Here, we present a detailed polyphasic analysis of 10 bacterial strains isolated from three coastal lichens Lichina confinis, Lichina pygmaea and Roccella fuciformis with SSU rRNA gene sequences identical to the type strain of Streptomyces cyaneofuscatus. This analysis included phenotypic, microscopic, genetic and genomic comparisons and showed that despite their identical SSU rRNA sequences the …

Assessing The Influence Of Temporal Autocorrelations On The Population Dynamics Of A Disturbance Specialist Plant Population In A Random Environment, Eric A. Eager, Diana Pilson, Helen M. Alexander, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Biological populations are strongly influenced by random variations in their environment, which are often autocorrelated in time. For disturbance specialist plant populations, the frequency and intensity of environmental stochasticity (via disturbances) can drive the qualitative nature of their population dynamics. In this article, we extended our earlier model to explore the effect of temporally autocorrelated disturbances on population persistence. In our earlier work, we only assumed disturbances were independent and identically distributed in time. We proved that the plant seed bank population converges in distribution, and we showed that the mean and variance in seed bank population size were both …

Geographical Variation In Community Divergence: Insights From Tropical Forest Monodominance By Ectomycorrhizal Trees*, Tadashi Fukami, Mifuyu Nakajima, Claire Fortunel, Paul V. Fine, Christopher Baraloto, Sabrina E. Russo, Kabir G. Peay

School of Biological Sciences: Faculty Publications

Convergence occurs in both species traits and community structure, but how convergence at the two scales influences each other remains unclear. To address this question, we focus on tropical forest monodominance, in which a single, often ectomycorrhizal (EM) tree species occasionally dominates forest stands within a landscape otherwise characterized by diverse communities of arbuscular mycorrhizal (AM) trees. Such monodominance is a striking potential example of community divergence resulting in alternative stable states. However, it is observed only in some tropical regions. A diverse suite of AM and EM trees locally codominate forest stands elsewhere. We develop a hypothesis to explain …

Ectoparasitic Mites Of The Genus Gigantolaelaps (Acari: Mesostigmata: Laelapidae) Associated With Small Mammals Of The Genus Nephelomys (Rodentia: Sigmodontinae), Including Two New Species From Peru, Donald D. Gettinger, Scott Lyell Gardner

Scott L. Gardner Publications

An extensive survey of small mammals and ectoparasites along an altitudinal transect in the Manu Biodiversity Reserve in Peru found the sigmodontine rodent genus Nephelomys infested by mites of the genus Gigantolaelaps Fonseca, 1939. Two distinct species co-occurred exclusively in the pelage of Nephelomys keaysi, G. inca Fonseca and G. minima n. sp. Nephelomys levipes, which replaces N. keaysi at higher elevations, was infested exclusively with a single new species, G. nebulosa n. sp. In this paper, we formally describe these new mite species, and provide more information on the morphology of G. inca.

Identification Of The Atpase Subunit Of The Primary Maltose Transporter In The Hyperthermophilic Anaerobe Thermotoga Maritima, Raghuveer Singh, Derrick White, Paul H. Blum

School of Biological Sciences: Faculty Publications

Thermotoga maritima is a hyperthermophilic anaerobic bacterium that produces molecular hydrogen (H₂) by fermentation. It catabolizes a broad range of carbohydrates through the action of diverse ABC transporters. However, in T. maritima and related species, highly similar genes with ambiguous annotation obscure a precise understanding of genome function. In T. maritima, three putative malK genes, all annotated as ATPase subunits, exhibited high identity to each other. To distinguish between these genes, malK disruption mutants were constructed by gene replacement, and the resulting mutant cell lines were characterized. Only a disruption of malK3 produced a defect in maltose …

Abundance And Distribution Of Microbial Cells And Viruses In An Alluvial Aquifer, Donald Pan, Jason Nolan, Kenneth H. Williams, Karrie A. Weber

School of Biological Sciences: Faculty Publications

Viruses are the most abundant biological entity on Earth and their interactions with microbial communities are recognized to influence microbial ecology and impact biogeochemical cycling in various ecosystems. While the factors that control the distribution of viruses in surface aquatic environments are well-characterized, the abundance and distribution of continental subsurface viruses with respect to microbial abundance and biogeochemical parameters have not yet been established. In order to begin to understand the factors governing virus distribution in subsurface environments, we assessed microbial cell and virus abundance in groundwater concurrent with groundwater chemistry in a uranium impacted alluvial aquifer adjoining the Colorado …

How Question Types Reveal Student Thinking: An Experimental Comparison Of Multiple-True-False And Free-Response Formats, Joanna K. Hubbard, Macy A. Potts, Brian Couch

School of Biological Sciences: Faculty Publications

Assessments represent an important component of undergraduate courses because they affect how students interact with course content and gauge student achievement of course objectives. To make decisions on assessment design, instructors must understand the affordances and limitations of available question formats. Here, we use a crossover experimental design to identify differences in how multiple-true-false (MTF) and free-response (FR) exam questions reveal student thinking regarding specific conceptions. We report that correct response rates correlate across the two formats but that a higher percentage of students provide correct responses for MTF questions. We find that MTF questions reveal a high prevalence of …

Nitrogen Addition And Ecosystem Functioning: Changes In Species Composition Leaf Traits Amplify Increases In Leaf Area Index And Canopy Chlorophyll, Anna R. Tatarko

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

Increased nutrient inputs can cause shifts in plant community composition and plant functional traits, both of which affect ecosystem function. We studied community- and species-level changes in specific leaf area (SLA), chlorophyll, leaf thickness, leaf toughness, plant height and leaf dry matter content (LDMC) in a full factorial nitrogen (N), phosphorus (P), potassium (K) fertilization experiment in a semi-arid grassland. Nitrogen was the only nutrient addition to significantly affect leaf functional traits, and N addition increased community weighted SLA by 19%, leaf chlorophyll content by 34%, height by 26%, and resulted in an 11% decrease in LDMC while leaf thickness …

Nutrient Addition Shifts Plant Community Composition Towards Earlier Flowering Species In Some Prairie Ecoregions In The U.S. Central Plains, Lori A. Biederman, Brent Mortensen, Philip Fay, Nicole Hagenah, Johannes M. H. Knops, Kimberly J. La Pierre, Ramesh Laungani, Eric Lind, Rebecca Mcculley, Sally Power, Eric W. Seabloom, Pedro Tognetti

School of Biological Sciences: Faculty Publications

The distribution of flowering across the growing season is governed by each species' evolutionary history and climatic variability. However, global change factors, such as eutrophication and invasion, can alter plant community composition and thus change the distribution of flowering across the growing season. We examined three ecoregions (tall-, mixed, and short-grass prairie) across the U.S. Central Plains to determine how nutrient (nitrogen (N), phosphorus, and potassium (+micronutrient)) addition alters the temporal patterns of plant flowering traits. We calculated total community flowering potential (FP) by distributing peakseason plant cover values across the growing season, allocating each species' cover to only those …

Behavioral Plasticity Across Non-Social Contexts In Female Green Swordtails, Xiphophorus Hellerii, 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 …

Phytohormone Signaling In Chlorella Sorokiniana: Perspectives On The Evolution Of Plant Cell-To-Cell Signaling, Maya Khasin

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

Cell-to-cell communication is a key aspect of microbial physiology and population dynamics, and a cornerstone in understanding the evolution of multicellularity. Quorum sensing in bacteria is a canonical example of microbial cell-to-cell signaling, in which bacteria use small molecule signals in order to monitor their population size and modulate their physiology accordingly. We propose that the evolution of plant hormone signaling arose in unicellular green algae, analogously to quorum sensing in bacteria, and that the complexity of these pathways required the recruitment of increasingly specific enzymes to increasingly sophisticated gene networks throughout the course of phytohormone signaling evolution. Using Chlorella …

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 …

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 …

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 …

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 …