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Full-Text Articles in Life Sciences
Morphological Changes Of The Asian Shore Crab Across Latitudes, Ainslee Mcmullin, Blaine D. Griffen
Morphological Changes Of The Asian Shore Crab Across Latitudes, Ainslee Mcmullin, Blaine D. Griffen
Library/Life Sciences Undergraduate Poster Competition 2022
The Asian shore crab, Hemigrapsus sanguineus , is an invasive species that has rapidly spread across the Eastern United States coastline. First observed in North America in 1988, its range currently extends from Maine to North Carolina. H. sanguineus has adapted very well to this region and has displaced several native species as the dominant crab in rocky intertidal habitats. Although the Asian shore crab’s biology and interactions with native species has been well studied, larger scale impacts (economic, potential further spread, community ecology, etc.) are under researched. We collected specimen samples of H. sanguineus throughout its entire East coast …
Classification Of Planetary Craters Using Outline-Based Morphometrics, Thomas J. Slezak, Jani Radebaugh, Eric H. Christiansen, Mark C. Belk
Classification Of Planetary Craters Using Outline-Based Morphometrics, Thomas J. Slezak, Jani Radebaugh, Eric H. Christiansen, Mark C. Belk
Faculty Publications
The morphologies of craters on planetary surfaces reveal clues about the geologic mechanisms by which they originate and subsequently evolve, as well as the materials and physical variables inherent to the environment in which they formed. We carried out a quantitative multivariate analysis of shape descriptors derived from the outlines of craters formed by volcanic processes on Mars, Io, and Earth and by impact cratering on the Moon using elliptic Fourier analysis (EFA) and the Zahn-Roskies (Z-R) shape function. Canonical variate analysis (CVA) was used to construct a statistical model of differences between the crater groups to classify …
Does Negative Frequency-Dependent Selection Maintain Gonopodial Asymmetry In A Livebearing Fish?, Mary-Elise Johnson
Does Negative Frequency-Dependent Selection Maintain Gonopodial Asymmetry In A Livebearing Fish?, Mary-Elise Johnson
Undergraduate Honors Theses
How genetic variation is maintained in the face of strong natural selection is an important problem in evolutionary biology. Selection should erode genetic diversity, leading to more and more homogeneous populations. Yet in nature, we commonly see high degrees of genetic variation, even for traits that are important to fitness. Negative frequency-dependent selection, a balancing selective force that favors traits when they are rare but not when they are common, is a mechanism proposed to maintain polymorphisms in a population. However, there is little empirical data to demonstrate how negative frequency-dependent selection sustains variation. Xenophallus umbratilis is a bilaterally symmetrical …
Morphological Convergence During Pregnancy Among Predator And Nonpredator Populations Of The Livebearing Fish Brachyrhaphis Rhabdophora (Teleostei: Poeciliidae), Jeff S. Wesner, Eric J. Billman, Adam Meier, Mark C. Belk
Morphological Convergence During Pregnancy Among Predator And Nonpredator Populations Of The Livebearing Fish Brachyrhaphis Rhabdophora (Teleostei: Poeciliidae), Jeff S. Wesner, Eric J. Billman, Adam Meier, Mark C. Belk
Faculty Publications
Predation can drive morphological divergence in prey populations, although examples of divergent selection are typically limited to nonreproductive individuals. In livebearing females, shape often changes drastically during pregnancy, reducing speed and mobility and enhancing susceptibility to predation. In the present study, we document morphological divergence among populations of nonreproductive female livebearing fish (Brachyrhaphis rhabdophora) in predator and nonpredator environments. We then test the hypothesis that shape differences among nonreproductive females are maintained among reproductive females between predator and nonpredator environments. Nonreproductive females in predator environments had larger caudal regions and more fusiform bodies than females in nonpredator environments; …
Assessing Traditional Morphology- And Chemistry-Based Species Circumspections In Lichenized Ascomycetes: Character Evolution And Molecular Species Delimitation In Common Western North American Lichens, Steven Leavitt
Theses and Dissertations
Accurate species delimitation has critical implications for ecological and conservation studies; and for understanding factors driving diversification. However, a growing body of evidence indicates that morphology-based species circumspection in lichenized ascomycetes often fails to accurately represent the number of fungal species. The use of molecular data in lichen systematics provides an important alternative to traditional morphological characters for identifying natural groups and assessing evolutionary histories in challenging lichen taxa. In this work, I examined two common lichen-forming genera in western North America, Rhizoplaca and Xanthoparmelia, as models for investigating character evolution, species delimitation in morphologically and chemically diverse species, …
Utilization Of Phylogenetic Systematics, Molecular Evolution, And Comparative Transcriptomics To Address Aspects Of Nematode And Bacterial Evolution, Scott M. Peat
Theses and Dissertations
Both insect parasitic/entomopathogenic nematodes and plant parasitic nematodes are of great economic importance. Insect parasitic/entomopathogenic nematodes provide an environmentally safe and effective method to control numerous insect pests worldwide. Alternatively, plant parasitic nematodes cause billions of dollars in crop loss worldwide. Because of these impacts, it is important to understand how these nematodes evolve, and, in the case of entomopathogenic nematodes, how their bacterial symbionts evolve. This dissertation contains six chapters. Chapter one is a review of DNA markers and their use in the phylogenetic systematics of entomopathogenic and insect-parasitic nematodes as well as a review of phylogenetic, co-phylogenetic, and …