Life Sciences Commons^™

Variation And Adaptation In Guppies And Gambusia, Alan L. Gillen, Anna Collins

Faculty Publications and Presentations

The guppy fish is considered by many to be a symbol of fertility, renewal, and growth. Gambusia are likely relatives of guppies and are known as mosquito fish because they largely prey on mosquito larvae. For a century, they have been used locally and globally in mosquito control. Guppies, Endler’s livebearers, and Gambusia are in the Poeciliidae family and freely interbreed in the wild. They are assumed to be in the same baramin or created kind. Their purpose in creation is often associated with harmony, balance, and abundance. It appears that the Poeciliidae family was designed with an array of …

Hybridization And Gene Expression: Beyond Differentially Expressed Genes, Anna Runemark, Emily C. Moore, Erica L. Larson

School of Biological Sciences: Faculty Publications

Gene expression has a key role in reproductive isolation, and studies of hybrid gene expression have identified mechanisms causing hybrid sterility. Here, we review the evidence for altered gene expression following hybridization and outline the mechanisms shown to contribute to altered gene expression in hybrids. Transgressive gene expression, transcending that of both parental species, is pervasive in early generation sterile hybrids, but also frequently observed in viable, fertile hybrids. We highlight studies showing that hybridization can result in transgressive gene expression, also in established hybrid lineages or species. Such extreme patterns of gene expression in stabilized hybrid taxa suggest that …

Speciation Jigsaw Activity, Erika Crispo

Open Educational Resources

What is a species? Why are there so many species on the planet? The question of why we have different species of organisms was the key thesis of Charles Darwin’s most famous book, On the Origin of Species.While several definitions of what constitutes a species exists, the most common definition lies within thebiological species concept. This concept states that different species exist when two individuals of different sexes are unable to reproduce with one another to yield viable offspring in the wild. A major limitation of this definition is that it can only be applied to sexually reproducing organisms that …

Hybrid Sterility, Genetic Conflict And Complex Speciation: Lessons From The Drosophila Simulans Clade Species, Daven C. Presgraves, Colin D. Meiklejohn

School of Biological Sciences: Faculty Publications

The three fruit fly species of the Drosophila simulans clade— D. simulans, D. mauritiana, and D. sechellia— have served as important models in speciation genetics for over 40 years. These species are reproductively isolated by geography, ecology, sexual signals, postmating-prezygotic interactions, and postzygotic genetic incompatibilities. All pairwise crosses between these species conform to Haldane’s rule, producing fertile F1 hybrid females and sterile F1 hybrid males. The close phylogenetic proximity of the D. simulans clade species to the model organism, D. melanogaster, has empowered genetic analyses of their species differences, including reproductive incompatibilities. But perhaps no phenotype has been subject to …

Epigenetics As Driver Of Adaptation And Diversification In Microbial Eukaryotes, Agnes K.M. Weiner, Laura A. Katz

Biological Sciences: Faculty Publications

No abstract provided.

Sister Species Diverge In Modality-Specific Courtship Signal Form And Function, Eileen Hebets, Mitch Bern, Rowan H. Mcginley, Andy Roberts, Arik Kershenbaum, James Starrett, Jason E. Bond

School of Biological Sciences: Faculty Publications

Understanding the relative importance of different sources of selection (e.g., the environment, social/sexual selection) on the divergence or convergence of reproductive communication can shed light on the origin, maintenance, or even disappearance of species boundaries. Using a multistep approach, we tested the hypothesis that two presumed sister species of wolf spider with overlapping ranges and microhabitat use, yet differing degrees of sexual dimorphism, have diverged in their reliance on modality- specific courtship signaling. We predicted that male Schizocosa crassipalpata (no ornamentation) rely predominantly on diet-dependent vibratory signaling for mating success. In contrast, we predicted that male S. bilineata (black foreleg …

Introduction To Neutrosophic Genetics, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

Neutrosophic Genetics is the study of genetics using neutrosophic logic, set, probability, statistics, measure and other neutrosophic tools and procedures. In this paper, based on the Neutrosophic Theory of Evolution (that includes degrees of Evolution, Neutrality (or Indeterminacy), and Involution) – as extension of Darwin’s Theory of Evolution, we show the applicability of neutrosophy in genetics, and we present within the frame of neutrosophic genetics the following concepts: neutrosophic mutation, neutrosophic speciation, and neutrosophic coevolution.

Genetic Basis Of Hybrid Sterility Between Drosophila Pseudoobscura And D. Persimilis, Alannah J.P. Mattice

Electronic Thesis and Dissertation Repository

Speciation is the underlying process that leads to formation of new species, and therefore is the basis of biodiversity. Genes involved in each stage of speciation, such as those involved in interspecies sterility, remain elusive. Male hybrid sterility and postzygotic isolation between Drosophila pseudoobscura and D. persimilis was examined in this study through backcrossing of female hybrids into each parental line (introgression), selecting for a sterile sperm phenotype, needle-eye sperm. Sperm phenotypes did not separate through backcrossing; instead, males presented with multiple sperm phenotypes. A relationship between the phenotypes observed and the potential genes involved was examined through whole genome …

Life History Divergence In Livebearing Fishes In Response To Predation: Is There A Microevolution To Macroevolution Barrier?, Mark C. Belk, Spencer J. Ingley, Jerald B. Johnson

Faculty Publications

A central problem in evolutionary biology is to determine whether adaptive phenotypic variation within species (microevolution) ultimately gives rise to new species (macroevolution). Predation environment can select for trait divergence among populations within species. The implied hypothesis is that the selection resulting from predation environment that creates population divergence within species would continue across the speciation boundary such that patterns of divergence after speciation would be a magnified accumulation of the trait variation observed before speciation. In this paper, we test for congruence in the mechanisms of microevolution and macroevolution by comparing the patterns of life history divergence among three …

Phenotypic Divergence In Two Sibling Species Of Shorebird: Common Snipe And Wilson’S Snipe (Charadriiformes: Scolopacidae), Tiago M. Rodrigues, Edward H. Miller, Sergei V. Drovetski, Robert M. Zink, Jon Fjeldså, David Gonçalves

School of Biological Sciences: Faculty Publications

Natural and social selection are among the main shapers of biological diversity but their relative importance in divergence remains understudied. Additionally, although neutral evolutionary processes may promote phenotypic divergence, their potential contribution in speciation is often overlooked in studies of comparative morphology. In this study, we investigated phenotypic differentiation in two allopatric shorebirds: the Palaearctic Common Snipe Gallinago gallinago and the Nearctic Wilson’s Snipe Gallinago delicata. Specimens of Common Snipe (n = 355 skins, n = 163 skeletons) and Wilson’s Snipe (n = 403 skins, n = 141 skeletons) in natural history collections were examined to quantify differences in skeletal …

Demonstrating Mate Choice Copying In Spiders Requires Further Research, R. Tucker Gilman, Kasey Fowler-Finn, Eileen A. Hebets

Eileen Hebets Publications

Mate choice copying—when individuals learn to prefer mates or mate types that have been chosen by others—can influence trait evo-lution and speciation (Varela et al. 2018; Dion et al. 2019). Most examples of mate choice copying are from fish, birds, and mammals including humans (Varela et al. 2018). However, 2 invertebrate examples—fruit flies and wolf spiders—have been used to argue that the phenomenon may be phylogenetically widespread, and perhaps the rule rather than the exception in nature (Varela et al. 2018). Here, we revisit the evidence for mate choice copying in wolf spiders (Fowler-Finn et al. 2015) in light of …

Hybrid Zone Barriers Comparative Data Set, David L. Field

Research Datasets

Many recent studies have addressed the mechanisms operating during the early stages of speciation, but surprisingly few studies have tested theoretical predictions on the evolution of strong reproductive isolation (RI). To help address this gap, we first undertook a quantitative review of the hybrid zone literature for flowering plants in relation to reproductive barriers. Then, using Populus as an exemplary model group, we analysed genome-wide variation for phylogenetic tree topologies in both early- and late-stage speciation taxa to determine how these patterns may be related to the genomic architecture of RI. Our plant literature survey revealed variation in barrier complexity …

Persistence Of A Geographically-Stable Hybrid Zone In Puerto Rican Dwarf Geckos, Brendan J. Pinto, James Titus-Mcquillan, Juan D. Daza, Tony Gamble

Biological Sciences Faculty Research and Publications

Determining the mechanisms that create and maintain biodiversity is a central question in ecology and evolution. Speciation is the process that creates biodiversity. Speciation is mediated by incompatibilities that lead to reproductive isolation between divergent populations and these incompatibilities can be observed in hybrid zones. Gecko lizards are a speciose clade possessing an impressive diversity of behavioral and morphological traits. In geckos, however, our understanding of the speciation process is negligible. To address this gap, we used genetic sequence data (both mitochondrial and nuclear markers) to revisit a putative hybrid zone between Sphaerodactylus nicholsi and Sphaerodactylus townsendi in Puerto Rico, …

Evolution Of The Caribbean Species Of Columnea (Gesneriaceae) With An Emphasis On The Jamaican Species, James F. Smith, Maggie T.-Y. Ooi, Lacie J. Schulte, Keron C. St.E. Campbell, Judeen Meikle, John L. Clark

Biology Faculty Publications and Presentations

Premise of research. Biogeography has improved understanding of evolution and diversification of organisms on both continental and island systems. One complicated island group in terms of geological history and biogeographic pattern is the Caribbean island system. A comparison across taxonomic groups does not result in overarching patterns for this group of islands. Columnea has the greatest number of species endemic to the Caribbean for any genus in Gesneriaceae that is not mostly endemic to the Caribbean with 16 species. Thirteen of these species are found on Jamaica, the remaining three each endemic to Cuba, Hispaniola, and Puerto Rico. In …

Uncovering Genomic Insights To The Dynamics And Mechanisms Of Speciation Using Lialis Burtonis And Heteronotia Binoei, James E. Titus-Mcquillan

Biology Dissertations

Species are fundamental entities in biology because their existence represents the cohesion that binds populations into a single unit. One facet of evolutionary biology is to identify the processes that cause the origin of species and maintain this cohesion apart from closely-related lineages. Two aims that speciation research attempts to answer are: (1) How do lineages diverge to form new species? and, (2) What prevents the merging of nascent species? One useful approach to address both questions is to study areas of contact where independent populations coexist and exchange genetic material. By investigating the size of contact zones, the extent …

Growing On A Scar: Population Genetics Of A Colorado Wildflower, Ace Spitzer

Ursidae: The Undergraduate Research Journal at the University of Northern Colorado

Speciation is a natural process in organisms caused by geographic isolation and adaptation to novel conditions. Human activities are a source for environmental changes in the air, soil, and waterways of an ecosystem. Organisms living around agricultural or industrial developments must adapt at a much faster rate than organisms subjected to natural selection pressures. Molecular biology technologies allow us to study genetic variation changes in populations subjected to human disturbances, with preliminary studies on plants showing greater genetic diversity in the genome, contrary to how organisms are expected to respond to anthropogenic pressures. Leaf tissue from the yarrow plant, Achillea …

Phylogeography Of The Neotropical Fish Genus Rhoadsia (Teleostei: Characidae) In Ecuador, Roberto Valentino Cucalón Tamayo

College of Science and Health Theses and Dissertations

Western Ecuador is considered a biodiversity hotspot. Nevertheless, studies of population genetic structure and variation are rare, especially in aquatic species. The genus Rhoadsia is an endemic freshwater fish in this region with two recognized species, Rhoadsia minor and R. altipinna. Little is known about the evolutionary relationships of their populations, and due to morphological similarities, their validity as distinct species has been questioned. The present study uses a phylogeographic approach to examine the evolutionary history of the genus and the validity of the two described species. Furthermore, I investigated the possible geographical origin of the genus based on patterns …

Distribution, Hybridization, And Taxonomic Status Of Two-Lined Salamanders (Eurycea Bislineata Complex) In Virginia And West Virginia, Paul W. Sattler, Timothy R. Brophy

Faculty Publications and Presentations

We used three diagnostic protein markers to examine salamanders of the Eurycea bislineata complex at 80 localities in Virginia and West Virginia. Two groups were strongly differentiated and met at a narrow contact zone. Rare hybridization was observed as well as limited introgression up to 5 km north and 10 km south of the contact zone. At the contact zone, 1% F1, 2% F2, 32% backcross, and 66% parental genotypes were observed. This pattern of parapatric distribution with limited hybridization and introgression argues for the recognition of Eurycea bislineata and E. cirrigera as separate species.

The Effects Of Heterospecific Mating Frequency On The Strength Of Cryptic Reproductive Barriers, Erica L. Larson, Margaret M. Brassil, Jonathan Maslan, Danielle Juárez, Flordeliza Lilagan, Hallie Tipton, Andrew Schweitzer, Joe Skillman, Kirsten Monsen, Merrill A. Peterson

Department of Biology Faculty Scholarship and Creative Works

Heterospecific mating frequency is critical to hybrid zone dynamics and can directly impact the strength of reproductive barriers and patterns of introgression. The effectiveness of post-mating prezygotic (PMPZ) reproductive barriers, which include reduced fecundity via heterospecific matings and conspecific sperm precedence, may depend on the number, identity and order of mates. Studies of PMPZ barriers suggest that they may be important in many systems, but whether these barriers are effective at realistic heterospecific mating frequencies has not been tested. Here, we evaluate the strength of cryptic reproductive isolation in two leaf beetles (Chrysochus auratus and C. cobaltinus) in the context …

Diversification In The Neotropics – Evolution And Population Genetics Of The Armored Catfish Hypancistrus Sp. From The Xingu River, Marcella Goncalves Santos

Electronic Theses and Dissertations

The Xingu River, one of the largest tributaries of the Amazon River, is currently in peril due to the recent construction of hydroelectric dams, but little is known about the numerous fish species it supports. This dissertation focuses on three pleco catfish species belonging to the genus Hypancistrus from the Xingu River with partially overlapping distributions: H. zebra, H. sp. (L174), and H. sp. (L66/333). Chapter 1 is a bibliographic review of Amazonian freshwater fish diversity, with the goal of discussing the hypotheses of speciation mechanisms that can be tested in this system, including the relative importance of ecological adaptation …

The Crs Ekinds Research Initiative: Where We Have Been And Where We Are Headed From Here, Jean K. Lightner, Kevin Anderson

Proceedings of the International Conference on Creationism

The eKINDS research initiative began in 2016 in an effort to accelerate research on numerous outstanding questions related the diversification and speciation of plants and animals. The research encompasses three broad topics: a) identification of created kinds, b) identification of mechanisms that drive diversification and speciation within created kinds, and c) detailed analysis of individual created kinds in an attempt to propose a robust natural history that delineates key events as organisms reproduced and filled the earth following the time of the Flood.

As part of the eKINDS project, a new statistical tool is being developed to take advantage of …

A Probable Case Of Incipient Speciation In Schizocosa Wolf Spiders Driven By Allochrony, Habitat Use, And Female Mate Choice, R. Tucker Gilman, Kasey Fowler-Finn, Eileen A. Hebets

School of Biological Sciences: Faculty Publications

There is growing evidence that speciation can occur between populations that are not geographically isolated. The emergence of assortative mating is believed to be critical to this process, but how assortative mating arises in diverging populations is poorly understood. The wolf spider genus Schizocosa has become a model system for studying mechanisms of assortative mating. We conducted a series of experiments to identify the factors that control mate-pair formation in a Schizocosa population that includes both ornamented and nonornamented males. We show that the population also includes two previously unrecognized female phenotypes. One female phenotype mates mostly or exclusively with …

Rattlesnake Genomics Illustrate Patterns Of Speciation, Adaptation, And Links Between Genome Structure And Function, Drew Roberts Schield

Biology Dissertations

Understanding the origins of species and biological novelties that allow them to thrive in diverse environments is a key goal in evolutionary biology, and new genomic methods are constantly enabling research using non-model species to address important questions related to speciation and adaptation. Using phylogeographic, population genetic, and comparative genomic methods, I demonstrate that North American rattlesnakes are a uniquely enriched system for investigating patterns and processes at the intersection of adaptation and speciation. Specifically, this dissertation explores the evolution of biological novelty at multiple scales, including the origins of reproductive incompatibilities during the process of gene flow in secondary …

Admixture, Evolution, And Variation In Reproductive Isolation In The Boechera Puberula Clade, Martin P. Schilling, Zachariah Gompert, Fay-Wei Li, Michael D. Windham, Paul G. Wolf

Biology Faculty Publications

Background

Hybridization is very common in plants, and the incorporation of new alleles into existing lineages (i.e. admixture) can blur species boundaries. However, admixture also has the potential to increase standing genetic variation. With new sequencing methods, we can now study admixture and reproductive isolation at a much finer scale than in the past. The genus Boechera is an extraordinary example of admixture, with over 400 hybrid derivates of varying ploidy levels. Yet, few studies have assessed admixture in this genus on a genomic scale.

Results

In this study, we used Genotyping-by-Sequencing (GBS) to clarify the evolution of the Boechera …

Evidence For Trait-Based Dominance In Occupancy Among Fossil Taxa And The Decoupling Of Macroecological And Macroevolutionary Success, Peter Wagner, Roy E. Plotnick, S. Kathleen Lyons

School of Biological Sciences: Faculty Publications

Biological systems provide examples of differential success among taxa, from ecosystems with a few dominant species (ecological success) to clades that possess far more species than sister clades (macroevolutionary success). Macroecological success, the occupation by a species or clade of an unusually high number of areas, has received less attention. If macroecological success reflects heritable traits, then successful species should be related. Genera composed of species possessing those traits should occupy more areas than genera with comparable species richness that lack such traits. Alternatively, if macroecological success reflects autapomorphic traits, then generic occupancy should be a by-product of species richness …

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 …

Cellular/Molecular Analysis Of Interspecies Sterile Male Hybrids In Drosophila, Rachelle L. Kanippayoor

Electronic Thesis and Dissertation Repository

Over time, genetic differences can accumulate between populations that are geographically separated. This genetic divergence can lead to the evolution of reproductive isolating mechanisms that reduce gene flow between the populations and, upon secondary contact, result in distinct species. The process of speciation is, thus, what accounts for the multitude of species that contribute to the rich biodiversity on Earth. Interspecies hybrid sterility is a postzygotic isolating mechanism that affects the development of hybrids, rendering them sterile. A notable trend, known as Haldane's Rule, describes that heterogametic individual (e.g. males in Drosophila) are more susceptible to sterility than homogametic …

Sexual Selection, Speciation And Constraints On Geographical Range Overlap In Birds, Christopher Cooney, Joseph A. Tobias, Jason T. Weir, Carlos A. Botero, Nathalie Seddon

Biology Faculty Publications & Presentations

The role of sexual selection as a driver of speciation remains unresolved, not least because we lack a clear empirical understanding of its influence on different phases of the speciation process. Here, using data from 1306 recent avian speciation events, we show that plumage dichromatism (a proxy for sexual selection) does not predict diversification rates, but instead explains the rate at which young lineages achieve geographical range overlap. Importantly, this effect is only significant when range overlap is narrow (< 20%). These findings are consistent with a ‘differential fusion’ model wherein sexual selection reduces rates of fusion among lineages undergoing secondary contact, facilitating parapatry or limited co-existence, whereas more extensive sympatry is contingent on additional factors such as ecological differentiation. Our results provide a more mechanistic explanation for why sexual selection appears to drive early stages of speciation while playing a seemingly limited role in determining broad-scale patterns of diversification.

Natural History And Evolution Of An Elevational Generalist, The Cinereous Conebill (Conirostrum Cinereum), Andrea N. Chavez, Chandresekhar Natarajan, Jay F. Storz, Angela Fago, Christopher C. Witt

Biology ETDs

Elevational generalism is relatively rare in the tropical Andes Mountains, likely owing to the inherent requirements of enduring a high degree of climatic zonation and coping with hypoxic stress. The Cinereous Conebill (Conirostrum cinereum) appears to be an exception, and inhabits a continuous elevational distribution that spans over 4,500 m. Two subspecies, cinereum and fraseri, are restricted to high elevations and may be isolated, whereas the third and most widespread, littorale, occurs continuously along the western slope of the Andes from 0 to over 4,500 m. First, we aim to characterize the morphology, genetics, and climatic …

Genetics Of Female Interspecific Mate Rejection In Species Of Drosophila, Ryan Calhoun

Electronic Thesis and Dissertation Repository

Speciation can occur when accumulated differences in mating behavior force diverging species to remain reproductively isolated from one another. A key determinant of behavioural isolation is the evolution of female mating preferences that prevent interspecific males from mating. However, no individual genes involved in species-specific preferences of females have yet been identified. Using various genetic mapping techniques available for studying strains and species of Drosophila, I identify candidate genes involved in D. simulans female discrimination against D. melanogaster males. One candidate gene in particular, Katanin-60, was selected for further characterization. Katanin-60 is a gene encoding a microtubule severing …