Life Sciences Commons^™

Developmental Nonlinearity Drives Phenotypic Robustness, Rebecca M. Green, Jennifer L. Fish, Nathan M. Young, Francis J. Smith, Benjamin Roberts, Katie Dolan, Irene Choi, Courtney L. Leach, Paul Gordon, James M. Cheverud, Charles C. Roseman, Trevor J. Williams, Ralph S. Marcucio, Benedikt Hallgrímsson

Biology: Faculty Publications and Other Works

Robustness to perturbation is a fundamental feature of complex organisms. Mutations are the raw material for evolution, yet robustness to their effects is required for species survival. The mechanisms that produce robustness are poorly understood. Nonlinearities are a ubiquitous feature of development that may link variation in development to phenotypic robustness. Here, we manipulate the gene dosage of a signaling molecule, Fgf8, a critical regulator of vertebrate development. We demonstrate that variation in Fgf8 expression has a nonlinear relationship to phenotypic variation, predicting levels of robustness among genotypes. Differences in robustness are not due to gene expression variance or …

Characterizing Mekk1: Candidate Behavioural Isolation Gene, Caryn Dooner

Electronic Thesis and Dissertation Repository

Behavioural isolation can occur due to divergence in aspects of courtship and mating, and can contribute to reproductive isolation. The purpose of this study is to determine how a gene, Mekk1, contributes to female rejection behaviour between D. melanogaster and D. simulans. Unique polymorphisms were identified within D. simulans Mekk1 that could contribute to behaviour, most of which are non-coding. Both transcripts of Mekk1 appear to be expressed at similar levels in D. simulans and D. melanogaster. These data also indicate that Mekk1 may be expressed in a specific region of the brain called the mushroom body, …

Why Does It Take Two To Tango? Lifetime Fitness Consequences Of Parental Care In A Burying Beetle, Ashlee N. Smith, J. Curtis Creighton, Mark C. Belk

Faculty Publications

In species that require parental care, each parent can either care for their offspring or leave them in the care of the other parent. For each parent this creates three possible parental care strategies: biparental care, uniparental (male or female) care, and uniparental desertion by either the male or female. The burying beetle, Nicrophorus orbicollis, typically exhibits biparental care of offspring, and thus provides a unique system that allows us to compare the fitness benefits of these parental care strategies in an unconfounded way. In this study, we assess the lifetime fitness of biparental care, uniparental care, and uniparental …

Characterizing The Evolutionary Path(S) To Early Homo, Lauren Schroeder, Charles C. Roseman, James M. Cheverud, Rebecca R. Ackermann

James Cheverud

Numerous studies suggest that the transition from Australopithecus to Homo was characterized by evolutionary innovation, resulting in the emergence and coexistence of a diversity of forms. However, the evolutionary processes necessary to drive such a transition have not been examined. Here, we apply statistical tests developed from quantitative evolutionary theory to assess whether morphological differences among late australopith and early Homo species in Africa have been shaped by natural selection. Where selection is demonstrated, we identify aspects of morphology that were most likely under selective pressure, and determine the nature (type, rate) of that selection. Results demonstrate that selection must …

Diaspora, A Large Family Of Ty3-Gypsy Retrotransposons In Glycine Max, Is An Envelope-Less Member Of An Endogenous Plant Retrovirus Lineage, Sho T. Yano, Bahman Panbehi, Arpita Das, Howard M. Laten

Howard Laten

Background The chromosomes of higher plants are littered with retrotransposons that, in many cases, constitute as much as 80% of plant genomes. Long terminal repeat retrotransposons have been especially successful colonizers of the chromosomes of higher plants and examinations of their function, evolution, and dispersal are essential to understanding the evolution of eukaryotic genomes. In soybean, several families of retrotransposons have been identified, including at least two that, by virtue of the presence of an envelope-like gene, may constitute endogenous retroviruses. However, most elements are highly degenerate and are often sequestered in regions of the genome that sequencing projects initially …

Adaptive Evolution And Inherent Tolerance To Extreme Thermal Environments, Jennifer Cox, Alyxandria Schubert, Michael Travisano, Catherine Putonti

Catherine Putonti

Background When introduced to novel environments, the ability for a species to survive and rapidly proliferate corresponds with its adaptive potential. Of the many factors that can yield an environment inhospitable to foreign species, phenotypic response to variation in the thermal climate has been observed within a wide variety of species. Experimental evolution studies using bacteriophage model systems have been able to elucidate mutations, which may correspond with the ability of phage to survive modest increases/decreases in the temperature of their environment. Results Phage ΦX174 was subjected to both elevated (50°C) and extreme (70°C+) temperatures for anywhere from a few …

The Genetic And Environmental Basis For Chc Biosynthesis In Drosophila, Heather Ke Ward

Electronic Thesis and Dissertation Repository

Cuticular hydrocarbons (CHCs) are produced by insects and primarily used to prevent desiccation. In Drosophila, certain compounds have secondary roles as infochemicals that may act during courtship to influence mate choice. Certain CHCs may stimulate courtship with heterospecifics or act to repel conspecifics. The CHC profile produced by an individual is the result of the interaction between its genetic background and the environment, though the genes that underlie species differences in CHC production and how the environment can modulate the abundance of individual compounds within a species is not well known. Here, candidate gene CG5946 was found to be …

Deep Ancestry Of Programmed Genome Rearrangement In Lampreys, Vladimir A. Timoshevskiy, Ralph T. Lampman, Jon E. Hess, Laurie L. Porter, Jeramiah J. Smith

Biology Faculty Publications

In most multicellular organisms, the structure and content of the genome is rigorously maintained over the course of development. However some species have evolved genome biologies that permit, or require, developmentally regulated changes in the physical structure and content of the genome (programmed genome rearrangement: PGR). Relatively few vertebrates are known to undergo PGR, although all agnathans surveyed to date (several hagfish and one lamprey: Petromyzon marinus) show evidence of large scale PGR. To further resolve the ancestry of PGR within vertebrates, we developed probes that allow simultaneous tracking of nearly all sequences eliminated by PGR in P. marinus and …

T6ss Intraspecific Competition Orchestrates Vibrio Cholerae Genotypic Diversity, Benjamin Kostiuk, Daniel Unterweger, Daniele Provenzano, Stefan Pukatzki

Biology Faculty Publications and Presentations

Vibrio cholerae is a diverse species that inhabits a wide range of environments from copepods in brackish water to the intestines of humans. In order to remain competitive, V. cholerae uses the versatile type-VI secretion system (T6SS) to secrete anti-prokaryotic and anti-eukaryotic effectors. In addition to competing with other bacterial species, V. cholerae strains also compete with one another. Some strains are able to coexist, and are referred to as belonging to the same compatibility group. Challenged by diverse competitors in various environments, different V. choleare strains secrete different combination of effectors - presumably to best suit their niche. Interestingly, …

The Discovery Of Xy Sex Chromosomes In A Boa And Python, Tony Gamble, Todd A. Castoe, Stuart V. Nielsen, Jason L. Banks, Daren C. Card, Drew R. Schield, Gordon W. Schuett, Warren Booth

Biological Sciences Faculty Research and Publications

For over 50 years, biologists have accepted that all extant snakes share the same ZW sex chromosomes derived from a common ancestor [1, 2, 3], with different species exhibiting sex chromosomes at varying stages of differentiation. Accordingly, snakes have been a well-studied model for sex chromosome evolution in animals [1, 4]. A review of the literature, however, reveals no compelling support that boas and pythons possess ZW sex chromosomes [2, 5]. Furthermore, phylogenetic patterns of facultative parthenogenesis in snakes and a sex-linked color mutation in the ball python (Python regius) are best explained by boas …

Review Of The Sub-Saharan Africa Species Of Dignomus And Phylogenetic Analysis Of The Bostrichoids (Coleoptera: Bostrichoidea: Ptinidae), Amelia Lesbeth Smith

Masters Theses & Specialist Projects

Sub-Saharan Africa is home to nine described species of Dignomus Wollaston, 1862. Study and dissection of specimens has led me to the hypothesis that there are nine undocumented species in this region. Descriptions and images of the new species are presented and discussed, along with a compiled list of all described species from the Sub- Saharan region. The probable biology as geographic distributions for members of the genus are also given.

Additionally, a phylogenetic analysis of 95 species of bostrichoids using CO1 molecular data was done with a focus on the origins of Dignomus and Pseudomezium. parsimony and bayesian analyses …

A Linkage Map For The Newt Notophthalmus Viridescens: Insights In Vertebrate Genome And Chromosome Evolution, Melissa C. Keinath, S. Randal Voss, Panagiotis A. Tsonis, Jeramiah J. Smith

Biology Faculty Publications

Genetic linkage maps are fundamental resources that enable diverse genetic and genomic approaches, including quantitative trait locus (QTL) analyses and comparative studies of genome evolution. It is straightforward to build linkage maps for species that are amenable to laboratory culture and genetic crossing designs, and that have relatively small genomes and few chromosomes. It is more difficult to generate linkage maps for species that do not meet these criteria. Here, we introduce a method to rapidly build linkage maps for salamanders, which are known for their enormous genome sizes. As proof of principle, we developed a linkage map with thousands …

Interaction Between Predation Environment And Diet Constrains Body Shape In Utah Chub, Gila Atraria (Cypriniformes: Cyprinidae), Trevor J. Williams, Jerald B. Johnson, Mark C. Belk

Faculty Publications

Evolution typically occurs in response to a suite of selective pressures. Yet, many studies of natural selection in the wild only investigate a single selective agent at a time. This can be problematic when selective agents act in non-additive ways. Here we evaluate the interactive effects of diet and predation on the evolution of body shape in the cyprinid fish Utah chub (Gila atraria). We found that both factors and the interaction between them are significant predictors of body shape. This interaction is likely a result of different forms of selective pressures, where predation is a stabilizing selective …

The Santa Ana Speckled Dace (Rhinichthys Osculus): Phylogeography And Molecular Evolution Of The Mitochondrial Dna Control Region, James Jay Vanmeter

Electronic Theses, Projects, and Dissertations

The purpose of this genetic study of the Santa Ana Speckled Dace Rhinichthys osculus was three-fold. The first goal was to characterize the molecular structure of the mtDNA control region of R. osculus. An 1143 base-pair region of the mitochondrial DNA genome, which included the complete control region was sequenced for all individuals. Analysis of the sequence data revealed that the molecular structure of the speckled dace control region was similar to the molecular structure described for other vertebrate taxa. The speckled dace control region contains three major domains, which vary in base frequency as well as in the frequency …

Oldest Skeleton Of A Plesiadapiform Provides Additional Evidence For An Exclusively Arboreal Radiation Of Stem Primates In The Palaeocene, Stephen B. Chester, Thomas E. Williamson, Jonathan I. Bloch, Mary T. Silcox, Eric J. Sargis

Publications and Research

Palaechthonid plesiadapiforms from the Palaeocene of western North America have long been recognized as among the oldest and most primitive euarchontan mammals, a group that includes extant primates, colugos and treeshrews. Despite their relatively sparse fossil record, palaechthonids have played an important role in discussions surrounding adaptive scenarios for primate origins for nearly a half-century. Likewise, palaechthonids have been considered important for understanding relationships among plesiadapiforms, with members of the group proposed as plausible ancestors of Paromomyidae and Microsyopidae. Here, we describe a dentally associated partial skeleton of Torrejonia wilsoni from the early Palaeocene (approx. 62Ma) of New Mexico, which …

Human Evolution And Divine Agency, Alexandra Rakestraw

Dialogue & Nexus

Modern Christians often find themselves at a crossroads when confronted with the two predominant understandings of human and universal origins. Plain sense readings of Genesis lead many to believe in a historical six-day creation that occurred in the past ten thousand years while proponents on the other side of the spectrum use current scientific understanding to support a creation that occurs through evolutionary means. How one views human origins has a profound impact on one’s concept of how God works in the cosmos. In this paper, I will lay out a background to better understand the characters of Adam and …

Moral Awareness, Original Sin And The Atonement, Tanner Gregory

Dialogue & Nexus

I will explore how evolution impacts the Christian notion of The Fall of man, and, ultimately, the atonement. Various theories of atonement in the Christian tradition generally assume universal and individual sinfulness in humanity. In some cases, this sinfulness is thought to be the result of a distinct moment of rebellion against God, and is transmitted to all of the descendants of Adam. Here, atonement involves Christ’s sacrifice as the means liberate humanity from the bondage of our sinful nature. Evolution collides with these traditional models. Instead of a creation originally void of death and later corrupted by sin, evolution …

Immunology Of The Gray Short-Tailed Opossum During Pregnancy And Prenatal Development, Victoria L. Hansen

Biology ETDs

Vertebrate species that bear live young have overcome the evolutionary challenge of maintaining both a functional adaptive immune system and viviparous life cycle. In normal pregnancy, viviparous mothers are able sustain and nourish a fetus that is genetically half non-self without mounting an immunological attack. In 1953 Sir Peter Medawar brought attention to the “enigma of the fetal graft” and immunologists have been puzzling out the intricacies of fetal tolerance ever since. Although viviparity has evolved in all jawed vertebrate lineages aside from Aves, the vast majority of reproductive immunology research has been limited to eutherian mammals. There are insights …

Novel Approaches To Exploring Silk Use Evolution In Spiders, Rachael Alfaro

Biology ETDs

Spider silk is enigmatic, and web structure, design, and adult morphology of the spinning apparatus of spiders once informed how systematists approached the spider phylogeny. The orb-web and adaptation of viscous silk was considered a key innovation leading to rapid diversification of spiders. However, the advent of molecular techniques including recent phylogenomics studies, overturned this major paradigm in spider evolution. Clades once considered monophyletic are no more. The orb-web is not a pinnacle of evolution, and the former sister group, using cribellate silk (loops of fibrils combed from a specialized silk plate on the abdomen), is now sister to the …

Evolution And The Fall, Andrew Tate

Dialogue & Nexus

Within Christianity, there are a spectrum of beliefs regarding the function and mode of baptism, what constitutes original sin (or in what form it exists), modes of worship, gender roles (or if they even exist). I will argue here that despite varying dogmas and ideologies one consistent position over two millennia is that Jesus, as the Son of God, came to the earth, died on a cross, and was raised from the grave. Following this is the belief that in some way through these actions, either natural or supernatural, he has given humanity the opportunity to be redeemed. Through this …

Divine Action And Teleology In An Evolutionary World, Emily Sparks

Dialogue & Nexus

In this paper I explore three possibilities: 1) whether or not there is room for divine action in a dynamic, undetermined, evolutionary world; 2) if divine action is necessary to explain the outcome of creation; and 3) if there is purpose (e.g. teleology) in such a world. I will address the implications of indeterminacy, parts-and-whole behavior (or emergence), and directionality for divine agency. Models of God’s action informed by these trends will be provided. Finally, I will explain the teleological implications of these discoveries and God’s action and conclude with implications to the Christian faith.

Phylogenetics, Biogeography, And Patterns Of Diversification Of Geckosacross The Sunda Shelf With An Emphasis On The Genuscnemaspis (Strauch, 1887), Perry Lee Wood

Theses and Dissertations

In my dissertation I investigate two genera of geckos (Cyrtodactylus and Cnemaspis) that are distributed across Southeast Asia with an emphasis on Cnemaspis. In Chapter 1 I use a multilocus dataset, ancestral area analyses, and molecular clock dating to generate a species level time calibrated phylogeny to test the monophyly of Cyrtodactylus and to identify major biogeographical patterns. I identified that Cyrtodactylus is monophyletic only if the the Sri Lankan genus often recognized as Geckoella is included. The results of the Biogeographical analyses reveal a west to east pattern of diversification. Chapter 2 I use a traditional morphological dataset to …

Phylogenetics, Biogeography, And Patterns Of Diversification Of Geckosacross The Sunda Shelf With An Emphasis On The Genuscnemaspis (Strauch, 1887), Perry Lee Wood

Theses and Dissertations

In my dissertation I investigate two genera of geckos (Cyrtodactylus and Cnemaspis) that are distributed across Southeast Asia with an emphasis on Cnemaspis. In Chapter 1 I use a multilocus dataset, ancestral area analyses, and molecular clock dating to generate a species level time calibrated phylogeny to test the monophyly of Cyrtodactylus and to identify major biogeographical patterns. I identified that Cyrtodactylus is monophyletic only if the the Sri Lankan genus often recognized as Geckoella is included. The results of the Biogeographical analyses reveal a west to east pattern of diversification. Chapter 2 I use a traditional morphological dataset to …

Hearing On The Fly: The Effects Of Wing Position On Noctuid Moth Hearing, Shira D. Gordon, Elizabeth Klenschi, James F. C. Windmill

Dartmouth Scholarship

The ear of the noctuid moth has only two auditory neurons, A1 and A2, which function in detecting predatory bats. However, the noctuid's ears are located on the thorax behind the wings. Therefore, as these moths need to hear during flight, it was hypothesized that wing position may affect their hearing. The wing was fixed in three different positions: up, flat and down. An additional subset of animals was measured with freely moving wings. In order to negate any possible acoustic shadowing or diffractive effects, all wings were snipped, leaving the proximal-most portion and the wing hinge intact. Results revealed …

Fundamental Theorems Of Evolution, David C. Queller

Biology Faculty Publications & Presentations

Evolutionary biology is undergirded by an extensive and impressive set of mathematical models. Yet only one result, Fisher’s theorem about selection and fitness, is generally accorded the status of a fundamental theorem. I argue that although its fundamental status is justified by its simplicity and scope, there are additional results that seem similarly fundamental. I suggest that the most fundamental theorem of evolution is the Price equation, both because of its simplicity and broad scope and because it can be used to derive four other familiar results that are similarly fundamental: Fisher’s average-excess equation, Robertson’s secondary theorem of natural selection, …

Mutations: Evolution's Disappointment, Georgia (Hickman) Purdom

Alumni Publications

No abstract provided.

A Model Of The Use Of Evolutionary Trees (Muet) To Inform K-14 Biology Education, Yi Kong, Ankita Thawani, Trevor R. Anderson, Nancy Pelaez

PIBERG Publications

Evolutionary trees are powerful tools used in modern biological research, and also commonly used in textbooks and classroom instruction. Studies have shown that K-14 students have difficulties interpreting evolutionary trees. To improve student learning about this topic, it is essential to teach them how to understand and use trees like professional biologists. Unfortunately, few currently used teaching frameworks for evolution instruction are designed for this purpose. In this study we developed the Model of the Use of Evolutionary Trees (MUET), a conceptual model that characterizes how evolutionary trees were used by professional biologists as represented in their research publications. The …

Primate Proteomic Composition Of Seminal Plasma And Prostate-Specific Transglutaminase Activity In Relation To Sexual Selection., Amanda M.C. Zielen

Electronic Theses and Dissertations

Humans (Homo sapiens), chimpanzees (Pan troglodytes), and gorillas (Gorilla gorilla) have diverse mating systems with varying levels of sperm competition. Several seminal plasma genes have been claimed to evolve under positive selection, while others are altered or lost. This study aims to identify biologically relevant differences among seminal plasma proteomes of primates in relation to mating systems and previous genomic studies. Seminal plasma from three individuals of each species were run in triplicate in shotgun liquid chromatography – tandem mass spectrometry (LC-MS/MS) and confirmed with Western blots. Over 7,000 peptides were identified across all …

Evolutionary Linkage Of Mimetic And Non-Mimetic Color Traits In A Coral Snake Mimicry Complex, John D. Curlis Jr

Electronic Theses and Dissertations

Color polymorphism in aposematic mimicry systems is a perplexing phenomenon for evolutionary biologists, as theoretically the benefits of converging on a model phenotype should constrain the evolution of phenotypic diversity in these systems (i.e., color polymorphism should not occur). Nevertheless, color polymorphism in mimicry systems is prevalent throughout many taxa. In some of these systems, the evolution of color polymorphism results in the existence of non-mimetic morphs, such as those that are cryptic. The case of ground snakes (Sonora semiannulata) is unique in that color polymorphism encompasses both mimetic and cryptic morphs, as well as individual mimetic and …

Crassulacean Acid Metabolism As A Continuous Trait: Variability In The Contribution Of Crassulacean Acid Metabolism (Cam) In Populations Of Portulacaria Afra, Lonnie J. Guralnick, Kate Gladsky

Arts & Sciences Faculty Publications

Portulacaria afra L. is a dominant facultative CAM species growing in the Southeastern Cape of South Africa. P. afra is well adapted to regions of the Spekboom thicket in areas of limited and sporadic rainfall. P. afra populations occur in isolated drainages. We hypothesized the utilization of CAM would vary in the different populations in response to rainfall and temperature gradients. Carbon isotope composition can be used to determine the contribution of CAM in leaf tissue. P. afra leaves of populations were analyzed in transects running south to north and east to west in locations from the coast to elevations …