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The Relationship Between Vertebral Osteology and Microhabitat and Prey-capture Methods in Snakes

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Vertebral osteology varies greatly among snake species. This variation may be related to specialization in microhabitat and prey-capture. Radiographs of eight preserved male specimens were taken in order to analyze

Vertebral osteology varies greatly among snake species. This variation may be related to specialization in microhabitat and prey-capture. Radiographs of eight preserved male specimens were taken in order to analyze the vertebral length and morphology of snakes which exhibit extreme characteristics in microhabitat utilization and prey-capture methods (highly arboreal, effective constrictor). This group includes two representatives each from four major families within Serpentes: Boidae, Pythonidae, Viperidae, and Colubridae. The four boids and pythons are effective constrictors, while the four vipers and colubrids are non-constricting. One specimen of each pair is highly arboreal, while the other is terrestrial. Findings support previous research in that constrictors had larger total numbers of vertebrae than non-constrictors. When average maximum adult length and morphology of axial musculature was taken into consideration, however, flexibility gained by vertebral number alone does not theoretically confer a mechanical advantage during constriction, at least among the specimens examined. All arboreal specimens had tails with a greater number of vertebrae than their con-familial terrestrial counterpart, implicating greater flexibility in the caudal region as an important characteristic for arboreality across taxa. Examination of segments of 10 vertebrae revealed that the greatest vertebral elongation occurred at the midpoint of the thoracic region. Reduction in size and length of tail vertebrae appears to occur independently of thoracic vertebrae. Colubrids, specifically, demonstrated a unique caudal vertebral elongation pattern which could potentially be advantageous for quick locomotion. These results indicate that caudal morphology may be more important in behavioral specialization than previously thought.

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Date Created
  • 2016-12

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Downwind

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In the 1950s-60s, the United States performed nuclear testing 60 miles north of Las Vegas. The prevailing winds carried radiation from those tests across the United States. It didn't take

In the 1950s-60s, the United States performed nuclear testing 60 miles north of Las Vegas. The prevailing winds carried radiation from those tests across the United States. It didn't take long for groups of people to begin developing cancer, possibly as a side effect of the testing. In 1990, Congress established a program to compensate downwind victims of the test site. But one portion of one county in Arizona was never compensated, despite the impact cancer had in the area. This documentary is their story. (Documentary and website accessible at downwinddocumentary.com)

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  • 2014-05

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The Aims and Structures of Research Projects That Use Gene Regulatory Information with Evolutionary Genetic Models

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At the interface of developmental biology and evolutionary biology, the very

criteria of scientific knowledge are up for grabs. A central issue is the status of evolutionary genetics models, which some

At the interface of developmental biology and evolutionary biology, the very

criteria of scientific knowledge are up for grabs. A central issue is the status of evolutionary genetics models, which some argue cannot coherently be used with complex gene regulatory network (GRN) models to explain the same evolutionary phenomena. Despite those claims, many researchers use evolutionary genetics models jointly with GRN models to study evolutionary phenomena.

How do those researchers deploy those two kinds of models so that they are consistent and compatible with each other? To address that question, this dissertation closely examines, dissects, and compares two recent research projects in which researchers jointly use the two kinds of models. To identify, select, reconstruct, describe, and compare those cases, I use methods from the empirical social sciences, such as digital corpus analysis, content analysis, and structured case analysis.

From those analyses, I infer three primary conclusions about projects of the kind studied. First, they employ an implicit concept of gene that enables the joint use of both kinds of models. Second, they pursue more epistemic aims besides mechanistic explanation of phenomena. Third, they don’t work to create and export broad synthesized theories. Rather, they focus on phenomena too complex to be understood by a common general theory, they distinguish parts of the phenomena, and they apply models from different theories to the different parts. For such projects, seemingly incompatible models are synthesized largely through mediated representations of complex phenomena.

The dissertation closes by proposing how developmental evolution, a field traditionally focused on macroevolution, might fruitfully expand its research agenda to include projects that study microevolution.

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Date Created
  • 2017