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Biology [clear filter]
Tuesday, April 24
 

12:00pm PDT

A New Species Of Dwarf Gecko (Sphaerodactylus) From The Virgin Islands
West Indian dwarf geckos, belonging to the genus Sphaerodactylus, are found throughout the Caribbean, with eleven species found on the Puerto Rican islands alone. Despite huge diversity and widespread abundance, comprehensive multi-locus phylogenetic studies of this group are largely lacking, or are based on older methods such as allozyme data. As part of a larger study on the phylogenetics of Puerto Rican herpetofauna, a molecular phylogeny of 16S RNA mitochondrial sequence data suggested that a cryptic and potentially new species of the Sphaerodactylus macrolepis complex might inhabit the Virgin Islands to the east of Puerto Rico. To confirm the relationship of this new species to Sphaerodactylus macrolepis sensu lato, we generated additional molecular sequence data for the mitochondrial genes CYTB and ND2, as well as for the nuclear genes RAG, ACM, and CMOS- a total of several thousand base pairs of data across most species of Puerto Rican Sphaerodactylus. Our combined analyses using Bayesian and Maximum Likelihood analyses support recognition of a new species of dwarf gecko from the Virgin Islands distinct from S. macrolepis, which we are in the process of naming. Subsequent studies will determine morphological, behavioral, and phenotypic uniqueness of this species.


Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Constructing A New Phylogenetic Tree To Trace The Evolution Of Ontogenetic Color Change In The Boas (Booidae)
Ontogenetic color change (OCC) in animals is the irreversible change in coloration occurring as an individual matures and develops from a juvenile to an adult. Because coloration is such an important aspect of the ecology, behavior, and natural history of an animal, OCC is often associated with either a shift in habitat use, diet, or sexual maturity. This trait has been observed across many vertebrate taxa from birds to fishes but has not been studied at all in the boas (Reptilia; superfamily Booidae) despite some dramatic known examples of OCC in this group. We compiled a database of all currently-recognized boa species and assessed whether they exhibit OCC or not using evidence from the primary and secondary literature, photographs of different life stages, and information from breeders. We then aligned genetic sequence data from an 1100 basepair mitochondrial gene sequenced across 90% of boa species (including newly-sequenced species never included in a molecular phylogeny before) and constructed a Bayesian phylogeny for the boas. We then mapped the presence of OCC onto the phylogeny as a binary trait using stochastic character mapping and analyzed whether OCC showed phylogenetic signal by performing a Pagel’s λ test. We also reconstructed ancestral character states (whether or not ancestors were likely to have exhibited OCC) and tested whether OCC evolved according to standard evolutionary models. Our results will provide insight into the evolution of OCC in the boas and allow for further research into the selective pressures that precipitated the evolution of this trait, whether this trait has evolved once or a multitude of times, and how it might affect fitness in some species.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Fire-Regime Management In Western North Carolina
Records of forest fire disturbance are relatively short (~50-100 years) in many regions across the southeastern United States. For much of the southeast, the historical fire records only cover approximately the past 50 years. Therefore, there is a need to develop proxy records of fire history to better understand the natural variability of fire regimes. This research will attempt to develop proxy fire histories using bog sediment records collected in Western North Carolina in the Southern Appalachian Mountains. Understanding the fire history will help to identify the underlying controls of the local fire regime, and to determine how ecosystems have responded to past changes in climate so that this information can be used to improve land-use and forest management plans in the future. Records of fire activity were determined by analyzing sedimentary macroscopic (>125 µm) charcoal preserved in the sediments of the Panthertown Valley Wetland Complex in Sapphire, NC. The sediment records were dated using 14C dating at Woods Hole - National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility, MA. Analysis of the regions fire histories will inform decision makers about the management of forest resources and guide the use of prescribed fire as a management tool in the region.


Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Method For Isolation Of Vomeronasal-2 Receptors From Vomeronasal Organ Cdna Library For Eventual Expression In Mammalian Cells
The vomeronasal organ (VNO) is a chemosensory organ present in amphibians, reptiles, and non-primate mammals. In mice, vomeronasal neurons express vomeronasal-1 receptors (V1R) or vomeronasal-2 receptors (V2R), both of which are G protein-coupled receptors involved in pheromone detection. V2Rs are expressed by the basal neurons of the VNO. They are of special interest because they are used to detect protein pheromones, the Major Urinary Proteins (MUPs), which induce intermale aggression, female responsiveness to mating, and territory marking behaviors. Because V2Rs use combinatorial coding instead of a labelled line coding strategy, linking pheromone responses to the correct V2R has so far been difficult. We designed primers for each V2R to amplify separate individual sequences from a cDNA library, which could then be transfected into cells using vectors. This cell culture method would allow for deorphanization of V2Rs by creating entire cell populations which only express a single V2R. With V2Rs deorphanized, mapping of pathways can begin from a bottom-up method, instead of the more difficult top-down approach. Here we show how to isolate and clone V2Rs for individual eventual expression in mammalian cells using DNA purification, Zero Blunt TOPO cloning PCR kit and ligation into mammalian vector. V2R 83 was successfully cloned into a bacterial vector with a complete sequence. Phosphatase treatments aided correct insert directionality when the V2R was transferred into mammalian vectors using blunt end cloning. Our results demonstrate progress towards setting up a cell culture based V2Rs expression system. This system will allow for further research to deorphanize individual V2Rs by matching them to their corresponding ligands. Stimulation of V2Rs reproducibly activate specific neural circuits in mouse brains, allowing for reliable study of how external environmental cues can direct behaviors. Cloning V2Rs is the first step to identify receptor-ligand interactions, which can be utilized for future research.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Molecular Phylogenetic Identification Of An Enigmatic Tree Frog From Conception Bank, Bahamas
During a 2017 survey of the remote Conception Island Bank, a small toepad sample of an unidentifiable tree frog (Hylide: Osteopilus) was collected by Dr. R. Graham Reynolds. Specimens of Osteopilus from this region appear much larger in size and much more colorful than populations throughout the rest of the Bahamas Archipelago. Due to the morphological ambiguity of the organism, we sought to investigate its phylogenetic affinities in comparison to other geographically proximal Osteopilus species. To do so, we extracted DNA from the toepad tissue of the unknown sample and one known sample of O. septentrionalis from Crooked Island, Bahamas using the Qiagen Wizard SV Kit, tested primers for the 16S mitochondrial gene obtained from a literature search, and then sequenced the sample using PCR. We then aligned the sequence with other Osteopilus species mined from the online resource GenBank and constructed a maximum-likelihood phylogenetic tree of West Indian hylid frogs using the RaxML algorithm in Geneious 10.0®. A BLAST search of the resulting sequence data yielded 98% sequence similarity to a confirmed O. septentrionalis specimen. Our phylogenetic tree revealed that the unknown population on Conception Bank is indeed O. septentrionalis. This raises some interesting questions with regard to the observed unique phenotype of frogs from this island. The large body size and unusual color might be owing to founder effects or local selective pressures. To deepen the mystery, other herpetofauna from the same island also exhibit gigantism- the Brown Anole has the largest body size for the species.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse

12:00pm PDT

Phylogenetic Comparative Analysis Of DNA Methylation Rates In Reptiles
In addition to playing a role in genomic function, DNA methylation influences evolution by regulating transcription. Technological advances, such as High-Performance Liquid Chromatography (RP-HPLC), have allowed scientists to explore genomic regulatory changes that contribute to species diversity and phenotypic variability. Epigenetic modifications of notable interest include 5-methylcytosine (5mC) and CpG (GC), as they are related to neutral selection on the cellular level. To understand how these regulatory changes evolve in a phylogenetic context, we analyzed these quantitative traits phylogenetically by mapping them to a mitochondrial phylogeny inferred de novo across 28 reptile species. Previous studies in reptiles concluded that there was no significant correlation between DNA methylation and environmental stimuli, but these studies did not correct for the non-independence of evolutionarily related species and thus violated a fundamental statistical assumption. To model these traits, we corrected these traits and ran phylogenetic comparative analyses in RStudio®. First, we examined the extent of the phylogenetic non-independence problem by estimating measures of phylogenetic signal for each quantitative trait. We then repeated regressions from a previous study, following phylogenetic correction, and inferred correlation between our two epigenetic modifications. Finally, we fit a series of evolutionary models to examine the evolution of these traits across the reptile phylogeny and selected the best model using an AICc model selection procedure. We found phylogenetic signal in GC but not 5mC, and that phylogenetic correction did not affect results, likely owing to the relatively small number of tips and the lack of phylogenetic signal in one of the traits. The evolution of these traits is best approximated by an Ornstein-Uhlenbeck model, suggesting that local optima exist for these quantitative characters and predicting a loss of phylogenetic signal (convergence or homoplasy). This study is important because the results can be used to understand the modifications to the genome influencing phenotypic diversity.

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Tuesday April 24, 2018 12:00pm - 1:30pm PDT
Sherrill Center Concourse