Evolution Commons^™

Photosynthetic Thermal Tolerance And Recovery To Short Duration Temperature Stress In Desert And Montane Plants: A Comparative Study, David William Gallagher

Master's Theses

• Climate change models predict an increase in frequency and amplitude of extreme weather events, including heat waves. To better predict how the composition and distribution of plant assemblages might respond to these changes in temperature, it is important to understand how species currently respond to these extremes. Photosynthetic thermal tolerance (T₂₅)and photosynthetic recovery (RT₂₅) were quantified in 27 species. We also studied the relationships between T₂₅, RT₂₅ and leaf mass per area (LMA). Leaf temperature was also monitored in the field.
• Leaves used in this study were collected from two distinct …

Joint Phenotypes, Evolutionary Conflict And The Fundamental Theorem Of Natural Selection, David C. Queller

Biology Faculty Research

Multiple organisms can sometimes affect a common phenotype. For example, the portion of a leaf eaten by an insect is a joint phenotype of the plant and insect and the amount of food obtained by an offspring can be a joint trait with its mother. Here, I describe the evolution of joint phenotypes in quantitative genetic terms. A joint phenotype for multiple species evolves as the sum of additive genetic variances in each species, weighted by the selection on each species. Selective conflict between the interactants occurs when selection takes opposite signs on the joint phenotype. The mean fitness of …

Insights Into The Development And Evolution Of Exaggerated Traits Using De Novo Transcriptomes Of Two Species Of Horned Scarab Beetles, Ian A. Warren, J. Cristobal Vera, Annika Johns, Robert Zinna, James H. Marden, Douglas J. Emlen, Ian Dworkin, Laura C. Lavine

Biological Sciences Faculty Publications

Scarab beetles exhibit an astonishing variety of rigid exo-skeletal outgrowths, known as ‘‘horns’’. These traits are often sexually dimorphic and vary dramatically across species in size, shape, location, and allometry with body size. In many species, the horn exhibits disproportionate growth resulting in an exaggerated allometric relationship with body size, as compared to other traits, such as wings, that grow proportionately with body size. Depending on the species, the smallest males either do not produce a horn at all, or they produce a disproportionately small horn for their body size. While the diversity of horn shapes and their behavioural ecology …

Developmental Link Between Sex And Nutrition; Doublesex Regulates Sex-Specific Mandible Growth Via Juvenile Hormone Signaling In Stag Beetles, Hiroki Gotoh, Hitoshi Miyakawa, Asano Ishikawa, Yuki Ishikawa, Yasuhiro Sugime, Douglas J. Emlen, Laura C. Lavine, Toru Miura

Biological Sciences Faculty Publications

Sexual dimorphisms in trait expression are widespread among animals and are especially pronounced in ornaments and weapons of sexual selection, which can attain exaggerated sizes. Expression of exaggerated traits is usually male-specific and nutrition sensitive. Consequently, the developmental mechanisms generating sexually dimorphic growth and nutritiondependent phenotypic plasticity are each likely to regulate the expression of extreme structures. Yet we know little about how either of these mechanisms work, much less how they might interact with each other. We investigated the developmental mechanisms of sex-specific mandible growth in the stag beetle Cyclommatus metallifer, focusing on doublesex gene function and its …

A Unique Covalent Bond In Basement Membrane Is A Primordial Innovation For Tissue Evolution, Aaron L. Fidler, Roberto M. Vanacore, Sergei V. Chetyrkin, Vadim K. Pedchenko, Gautam Bhave, Viravuth P. Yin, Cody L. Stothers, Kristie Lindsey Rose, W. Hayes Mcdonald, Travis A. Clark, Dorin-Bogdan Borza, Robert E. Steele, Michael T. Ivy, The Aspirnauts, Julie K. Hudson, Billy G. Hudson

Biology Faculty Research

We recently discovered that the collagen IV scaffolds of bovine, mouse, and Drosophila melanogaster tissues are stabilized by sulfilimine chemical bonds (S = N) (20⇓–22). The bond is a covalent cross-link between methionine-93 (Met93) and lysine-211 or hydroxylysine-211 (Lys211/Hyl211) residues that stabilizes the noncollagenous (NC1) interface of adjoining triple helical protomers (Fig. 1A). Peroxidasin, an animal heme peroxidase embedded in basement membrane, forms these sulfilimine cross-links by producing hypohalous acids as intermediates for Met93 oxidization (21, 22). Here, we explored whether the sulfilimine cross-link of collagen IV is a fundamental requirement in the genesis and evolution of tissues in Eumetazoa. …

Effects Of Toxic Cyanobacteria (Microcystis Aeruginosa) On The Feeding And Reproduction Ecology Of The Copepod Eurytemora Affinis From Green Bay, Lake Michigan, Nicholas J. Barrett

Lawrence University Honors Projects

Toxic Cyanobacteria is known to be a bad food source to consumers as well as a main contributor to harmful algal blooms. This study investigates the feeding relationship between an invasive copepod in the Great Lakes system, Eurytemora affinis, and a toxic strain of cyanobacteria, Microcystis aeruginosa. E.affinis has been shown to feed on toxic cyanobacteria. By measuring the filtering rate, ingestion rate, egg production and offspring size between three different food conditions, we hope to gain insight into the effects of toxic cyanobacteria on the feeding and reproduction of this copepod. Food sources include a good green algal …

Endogenous Ros Levels In C. Elegans Under Exogenous Stress Support Revision Of Oxidative Stress Theory Of Life-History Tradeoffs, Samson W. Smith, Leigh C. Latta Iv, Dee R. Denver, Suzanne Estes

Biology Faculty Publications and Presentations

Background: The oxidative stress theory of life-history tradeoffs states that oxidative stress caused by damaging free radicals directly underpins tradeoffs between reproduction and longevity by altering the allocation of energetic resources between these tasks. We test this theory by characterizing the effects of exogenous oxidative insult and its interaction with thermal stress and diet quality on a suite of life-history traits and correlations in Caenorhabditis elegans nematodes. We also quantify demographic aging rates and endogenous reactive oxygen species (ROS) levels in live animals.

Results: Our findings indicate a tradeoff between investment in reproduction and antioxidant defense (somatic maintenance) consistent with …

Patterns Of Maximum Body Size Evolution In Cenozoic Land Mammals: Eco-Evolutionary Processes And Abiotic Forcing, Juha J. Saarinen, Alison G. Boyer, James H. Brown, Daniel P. Costa, S.K. Morgan Ernest, Alistair R. Evans, Mikael Fortelius, John L. Gittleman, Marcus J. Hamilton, Larisa E, Harding, Kari Lintulaakso, S. Kathleen Lyons, Jordan G. Okie, Richard M. Sibly, Patrick R. Stephens, Jessica Theodor, Mark D. Uhen, Felisa A. Smith

School of Biological Sciences: Faculty Publications

There is accumulating evidence that macroevolutionary patterns of mammal evolution during the Cenozoic follow similar trajectories on different continents. This would suggest that such patterns are strongly determined by global abiotic factors, such as climate, or by basic eco-evolutionary processes such as filling of niches by specialization. The similarity of pattern would be expected to extend to the history of individual clades. Here, we investigate the temporal distribution of maximum size observed within individual orders globally and on separate continents. While the maximum size of individual orders of large land mammals show differences and comprise several families, the times at …

Tactical Escape Behavior And Performance Of A Small Sceloporine Lizard In Two High Risk Habitats, Seth Parker

College of Graduate Studies: Theses & Dissertations

The negotiation of uneven and complex terrain has implications for many small terrestrial vertebrates. Variation in the running surface due to obstacles like woody debris or vegetation can alter escape paths and running performance. Additionally, these microhabitat features can influence behavioral tactics in complex environments. The ability to negotiate physical barriers in dense environments likely influences survivorship through important ecological tasks, such as finding mates, foraging, and evading predators. The Florida scrub lizard (Sceloporus woodi) is a small, rare species endemic to two distinct and structurally complex environments in Florida, i.e. sand-pine scrub and longleaf pine-wiregrass sand-hills. The …

The Prevalence And Effect Of Wolbachia Infection On The Brown Widow Spider (Latrodectus Geometricus), Brittany Dane' Arrington

College of Graduate Studies: Theses & Dissertations

Wolbachia was recently identified in the Brown Widow Spider (Latrodectus geometricus). This symbiont has not previously been found in this genus, therefore the consequences on the host’s population dynamics are unknown. The frequency of endosymbiont infection can provide insight into the population dynamics of the host as this bacteria is known to alter host life history. In my 1^st chapter I determine the prevalence of Wolbachia pipentis infection in in the Brown Widow Spider (Latrodectus geometricus) from five locations in the Southeastern United States. Infection frequency differed significantly among sampling locations, ranging from 20% to …

Statistical And Comparative Phylogeography Of Mexican Freshwater Taxa In Extreme Aquatic Environments, Lyndon M. Coghill

LSU New Orleans Theses and Dissertations

Phylogeography aims to understand the processes that underlie the distribution of genetic variation within and among closely related species. Although the means by which this goal might be achieved differ considerably from those that spawned the field some thirty years ago, the foundation and conceptual breakthroughs made by Avise are nonetheless the same and are as relevant today as they were two decades ago. Namely, patterns of neutral genetic variation among individuals carry the signature of a species’ demographic past, and the spatial and temporal environmental heterogeneity across a species’ geographic range can influence patterns of evolutionary change. Aquatic systems …

The Roles Of Phenotypic Plasticity And Genotypic Specialization In High Altitude Adaptation, Danielle M. Tufts

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

In vertebrates living at high altitude, arterial hypoxemia may be ameliorated by reversible changes in the oxygen-carrying capacity of the blood (regulated by erythropoiesis) and/or changes in blood–oxygen affinity (regulated by allosteric effectors of hemoglobin function). These hematological traits often differ between taxa that are native to different elevational zones, but it is often unknown whether the observed physiological differences reflect fixed, genetically based differences or environmentally induced acclimatization responses (phenotypic plasticity). Here, we report measurements of hematological traits related to blood–O₂ transport in populations of deer mice (Peromyscus maniculatus) that are native to high- and low-altitude …

Reversible Inactivation And Desiccation Tolerance Of Silicified Viruses, James R. Laidler, Jessica A. Shugart, Sherry L. Cady, Keith S. Bahjat, Kenneth M. Stedman

Biology Faculty Publications and Presentations

Long-distance host-independent virus dispersal is poorly understood, especially for viruses found in isolated ecosystems. To
demonstrate a possible dispersal mechanism, we show that bacteriophage T4, archaeal virus Sulfolobus spindle-shaped virus Kamchatka, and vaccinia virus are reversibly inactivated by mineralization in silica under conditions similar to volcanic hot
springs. In contrast, bacteriophage PRD1 is not silicified. Moreover, silicification provides viruses with remarkable desiccation
resistance, which could allow extensive aerial dispersal.

Multivariate Sexual Selection On Male Song Structure In Wild Populations Of Sagebrush Crickets, Cyphoderris Strepitans (Orthoptera: Haglidae), Scott K. Sakaluk, Sandra Steiger, John Hunt, Geoffrey D. Ower, Kevin A. Judge, Rebecca A. Smith, Kyle J. Caron

Faculty Publications – Biological Sciences

While a number of studies have measured multivariate sexual selection actingon sexual signals in wild populations, few have confirmed these findings withexperimental manipulation. Sagebrush crickets are ideally suited to such investi-gations because mating imposes an unambiguous phenotypic marker on malesarising from nuptial feeding by females. We quantified sexual selection operat-ing on male song by recording songs of virgin and mated males captured fromthree wild populations. To determine the extent to which selection on malesong is influenced by female preference, we conducted a companion study inwhich we synthesized male songs and broadcast them to females in choicetrials. Multivariate selection analysis revealed …

Signatures Of Rapid Evolution In Urban And Rural Transcriptomes Of White-Footed Mice (Peromyscus Leucopus) In The New York Metropolitan Area, Stephen Edward Harris, Jason Munshi-South, Craig Oberfell, Rachel O'Neill

Publications and Research

Urbanization is a major cause of ecological degradation around the world, and human settlement in large cities is accelerating. New York City (NYC) is one of the oldest and most urbanized cities in North America, but still maintains 20% vegetation cover and substantial populations of some native wildlife. The white-footed mouse, Peromyscus leucopus, is a common resident of NYC’s forest fragments and an emerging model system for examining the evolutionary consequences of urbanization. In this study, we developed transcriptomic resources for urban P. leucopus to examine evolutionary changes in protein-coding regions for an exemplar “urban adapter.” We used Roche 454 …

Experimental Demonstration Of Accelerated Extinction In Source-Sink Metapopulations, John M. Drake, Blaine D. Griffen

Faculty Publications

Population extinction is a fundamental ecological process which may be aggravated by the exchange of organisms between productive (source) and unproductive (sink) habitat patches. The extent to which such source-sink exchange affects extinction rates is unknown. We conducted an experiment in which metapopulation effects could be distinguished from source-sink effects in laboratory populations of Daphnia magna. Time-to-extinction in this experiment was maximized at intermediate levels of habitat fragmentation, which is consistent with a minority of theoretical models. These results provided a baseline for comparison with experimental treatments designed to detect effects of concentrating resources in source patches. These treatments showed …

The Rate And Effects Of Spontaneous Mutation On Fitness Traits In The Social Amoeba, Dictyostelium Discoideum, David W. Hall, Sara Fox, Jennie J. Kuzdzal-Fick, Joan E. Strassmann, David C. Queller

Biology Faculty Research

We performed a mutation accumulation (MA) experiment in the social amoeba Dictyostelium discoideum to estimate the rate and distribution of effects of spontaneous mutations affecting eight putative fitness traits. We found that the per-generation mutation rate for most fitness components is 0.0019 mutations per haploid genome per generation or larger. This rate is an order of magnitude higher than estimates for fitness components in the unicellular eukaryote Saccharomyces cerevisiae, even though the base-pair substitution rate is two orders of magnitude lower. The high rate of fitness-altering mutations observed in this species may be partially explained by a large mutational target …

Evolution Of A Higher Intracellular Oxidizing Environment In Caenorhabditis Elegans Under Relaxed Selection, Joanna Joyner-Matos, Kiley A. Hicks, Dustin Cousins, Michelle Keller, Dee R. Denver, Charles F. Baer, Suzanne Estes

Biology Faculty Publications and Presentations

We explored the relationship between relaxed selection, oxidative stress, and spontaneous mutation in a set of mutationaccumulation (MA) lines of the nematode Caenorhabditis elegans and in their common ancestor. We measured steady-state levels of free radicals and oxidatively damaged guanosine nucleosides in the somatic tissues of five MA lines for which nuclear genome base substitution and GC-TA transversion frequencies are known. The two markers of oxidative stress are highly correlated and are elevated in the MA lines relative to the ancestor; point estimates of the per-generation rate of mutational decay (DM) of these measures of oxidative stress are similar to …

Surprisingly Little Population Genetic Structure In A Fungus-Associated Beetle Despite Its Exploitation Of Multiple Hosts, Corlett W. Wood , '08, H. M. Donald, Vincent A. Formica, E. D. Brodie Iii

Biology Faculty Works

In heterogeneous environments, landscape features directly affect the structure of genetic variation among populations by functioning as barriers to gene flow. Resource-associated population genetic structure, in which populations that use different resources (e.g., host plants) are genetically distinct, is a well-studied example of how environmental heterogeneity structures populations. However, the pattern that emerges in a given landscape should depend on its particular combination of resources. If resources constitute barriers to gene flow, population differentiation should be lowest in homogeneous landscapes, and highest where resources exist in equal proportions. In this study, we tested whether host community diversity affects population genetic …

The Effects Of Starvation Selection On Drosophila Melanogaster Life History And Development, Lauren A. Reynolds

UNLV Theses, Dissertations, Professional Papers, and Capstones

In nature, animals may endure periods of famine to complete their life cycles. Starvation stress will increase in populations as climates around the world change. To predict how populations may respond to such a stress, laboratory experimentation becomes essential. The evolutionary process of adaptation, its innovations and their trade-offs, can be studied in populations experiencing starvation stress. For this purpose outbred populations ofDrosophila melanogasterwere selected for starvation resistance in the laboratory.

After 60+ generations of starvation selection the starvation-selected flies have gone from surviving 2-3 days without food to 12-14 days without food. How this amazing feat of resistance is …

Spontaneous Male Death And Monogyny In The Dark Fishing Spider Dolomedes Tenebrosus Hentz, 1843 (Araneae, Pisauridae), Steven K. Schwartz

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

Male animals typically attempt to mate with multiple females in order to increase their reproductive success. In some species, however, males instead invest in fertilizing the eggs of a single female. Monogyny (male monogamy) is found in a diverse assemblage of taxa, and recent theoretical work reveals that a male-biased sex ratio can favor the evolution of this relatively rare mating system. We integrate this theoretical framework with field observations and laboratory experiments involving the sexually size dimorphic fishing spider, Dolomedes tenebrosus. Results from mating trials revealed a novel form of self-sacrifice behavior where males spontaneously die when they …

Melanin Concentration Gradients In Modern And Fossil Feathers, Daniel J. Field, Liliana D’Alba, Jakob Vinther, Samuel M. Webb, William Gearty, Matthew D. Shawkey

School of Biological Sciences: Faculty Publications

In birds and feathered non-avian dinosaurs, within-feather pigmentation patterns range from discrete spots and stripes to more subtle patterns, but the latter remain largely unstudied. A ,55 million year old fossil contour feather with a dark distal tip grading into a lighter base was recovered from the Fur Formation in Denmark. SEM and synchrotron-based trace metal mapping confirmed that this gradient was caused by differential concentration of melanin. To assess the potential ecological and phylogenetic prevalence of this pattern, we evaluated 321 modern samples from 18 orders within Aves. We observed that the pattern was found most frequently in distantly …

Reproductive Isolation In The Elegans-Group Of Caenorhabditis, Scott Everet Baird, Sara Rose Seibert

Biological Sciences Faculty Publications

Reproductive isolation is the basis of the Biological Species Definition and can be a driving force of speciation. Theoretical studies have provided models of how reproductive isolation can arise within individual species. Genetic tests of these models are limited to populations in which reproductive isolation is present but not complete. Here, reproductive isolation in the Elgans-Group of the nematode genus Caenorhabditis is reviewed. Pre-mating barriers, assortative fertilization and post-zygotic barriers all have been observed in this clade. In some combinations of species, fertile F1 hybrids can be obtained. Therefore, the Elegans-Group of Caenorhabditis is poised to become an important experimental …

To 'Die Hel' And Back. Expeditions Of The Phylogeny Of World Tachinidae Project. Part I: Western Cape, South Africa, Pierfilippo Cerretti, James E. O'Hara, John O. Stireman Iii, Isaac S. Winkler, Ashley H. Kirk-Spriggs

Biological Sciences Faculty Publications

The “Phylogeny of World Tachinidae” project kicked off with an operational meeting in June 2012 at the Canadian National Collection of Insects (CNC) in Ottawa. Goals were discussed, work plans prepared, and of course the destinations and timing of major field expeditions were debated. During our three years of National Science Foundation funding we hope to gather fresh material for molecular analysis from all biogeographic regions of the world.

Axolotl Paedomorphosis: A Comparison Of Juvenile, Metamorphic, And Paedomorphic Ambystoma Mexicanum Brain Gene Transcription, Carlena Johnson

Theses and Dissertations--Biology

Unlike many amphibians, the paedomorphic axolotl (Ambystoma mexicanum) rarely undergoes external morphological changes indicative of metamorphosis. However, internally, some axolotl tissues undergo cryptic metamorphic changes. A previous study examined interspecific patterns of larval brain gene expression and found that these species exhibited unique temporal expression patterns that were hypothesized to be morph specific. This thesis tested this hypothesis by examining differences in brain gene expression between juvenile (JUV), paedomorphic (PAED), and metamorphic (MET) axolotls. I identified 828 genes that were expressed differently between JUV, PAED, and MET. Expression estimates from JUV were compared to estimates from PAED and …

Insight Into Human Brain Evolution Through Phylogenetic Analysis And Comparative Genomics, Amy Marie Boddy

Wayne State University Dissertations

As a species, humans are often considered to be unique among mammals, with respect to their large brain size and enhanced cognitive abilities. Humans are the most encephalized mammals, with a brain that is six times larger than expected relative to body mass. Presumably, it is this high degree of encephalization that underlies our advanced cognitive abilities, including the skills needed for complex language and culture. Understanding how large brains evolved can shed light on what makes the human brain unique and introduce possible mechanism for human specific neurodegenerative diseases. This study takes a both a phenotypic and molecular approach …

Comparison Of Ectoparasitic Mite Loads Between Gonochoristic (Aspidoscelis Marmorata) And Parthenogenic (A. Tesselata) Syntopic Whiptail Lizards (Teiidae) From The Northern Chihuahuan Desert Of Trans-Pecos, Texas, William Dawson Lukefahr

Open Access Theses & Dissertations

The objective of this study was to compare the ectoparasitic loads between two syntopic whiptail lizard species (Teiidae) that differ in their reproductive modes; Aspidoscelis marmorata (bisexual) and A. tesselata (unisexual). The study site was located on Indio Mountains Research Station (IMRS) in a Chihuahuan Desert Scrub landscape in Hudspeth County, Texas. Previous studies conducted at IMRS showed the two species having similar diets, morphology, and reproductive characteristics, but fluctuated in nematode loads. No comparative study of ecotoparasitic mites (Eutrombicula alfreddugesi) between the two species has ever been done.

Aspidoscelis marmorata (n = 141) and A. tesselata (n = 144) …

Family Matters: An Analysis Of Genetic Relatedness Of Tetraclita Rubescens (The Pink Volcano Barnacle) Over Several Spatial Scales At Monterey And Bodega Bay, California, Kelly N. Chang

Scripps Senior Theses

Inbreeding involves the mating of closely related individuals at a higher frequency than at random; this can decrease the average fitness of populations and individuals by reducing the presence of heterozygotes and augmenting the expression of deleterious genes. Since marine invertebrates exhibit widespread dispersal, their potential for inbreeding is often disregarded. The adult sessile state of barnacles creates the potential for inbreeding as a result of necessary copulation between neighboring individuals. Depending on the degree of mixing that occurs during dispersal, closely related individuals or siblings may settle in close proximity, generating the possibility of kin aggregation and consequent inbreeding. …

Genetic Diversity In Populations Of Epiphanes Chihuahuaensis (Rotifera: Monogononta) In The Northern Chihuahuan Desert, Diego E. Reyes

Open Access Theses & Dissertations

1. Cryptic speciation in zooplankton is a phenomenon that has been recently gaining much attention. This is due in part to advances in molecular techniques which help in the identification of morphologically indistinct species. Organisms that have been traditionally believed to have cosmopolitan distributions are being found to be composed of cryptic species complexes with high levels of genetic divergence among lineages.

2. Epiphanes chihuahuaensis is a member in the Epiphanes senta species complex. In a previous study by Schröder & Walsh (2007), genetic data, along with morphological and reproductive isolation data were employed to help delineate four species within …

Gene Duplication And The Evolution Of Hemoglobin Isoform Differentiation In Birds, Michael T. Grispo

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

The majority of bird species co-express two functionally distinct hemoglobin (Hb) isoforms in definitive erythrocytes: HbA (the major adult Hb isoform, with α-chain subunits encoded by the α^A-globin gene) and HbD (the minor adult Hb isoform, with α-chain subunits encoded by the α^D-globin gene). The α^D-globin gene originated via tandem duplication of an embryonic α-like globin gene in the stem lineage of tetrapod vertebrates, which suggests the possibility that functional differentiation between the HbA and HbD isoforms may be attributable to a retained ancestral character state in HbD that harkens back to a primordial, …