Hellbender (Cryptobranchus alleganiensis) gene flow within rivers of the Missouri Ozark highlands

Title from PDF of title page (University of Missouri--Columbia, viewed on September 9, 2013).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Thesis advisor: Dr. Lori S. EggertIncludes bibliographical references.M.A. University of Missouri-Columbia 2013.Dissertations, Academic -- University of Missouri--Columbia -- Biological sciences."May 2013"For species of conservation concern, effective management includes maintaining robust population sizes while monitoring and promoting genetic variability. For hellbenders (Cryptobranchus alleganiensis), an aquatic salamander species experiencing dramatic declines in population size, little is known about genetic variation at the within-river scale and whether habitat patches within rivers are genetically and/or demographically connected. Given that suitable habitat patches are isolated, and that hellbenders exhibit extreme site fidelity, gene flow may be restricted among these discrete habitat patches. Using several polymorphic microsatellite loci, I assessed the fine-scale genetic relationships between hellbenders occupying various habitat patches within a river. My results indicate that a substantial amount of gene flow is occurring between habitat patches, with no evidence to support genetic differentiation between patches. Since dispersal is the mechanism driving gene flow, it can be inferred from this data that hellbenders disperse, with dispersal hypothesized to occur during the larval and/or juvenile phase. Dispersal can occur in both males and females. However, the propensity for one sex to disperse more frequently than the other is driven by evolutionary forces and mating strategies. Using molecular techniques, I investigated differential dispersal between males and females in order to evaluate sex-biased dispersal in hellbenders. My results suggest that male and female hellbenders disperse, and that both sexes contribute to the observed levels of gene flow. Because hellbender populations are experiencing low juvenile recruitment in addition to the declines in population size, I compared heterozygosity levels in survived and dead offspring to evaluate how genetic diversity influences offspring survival. My results suggest that heterozygosity-fitness correlations would be an intriguing area of research to pursue in future studies, and may give further insight into causes for hellbender declines

Development and Validation of an Environmental DNA Method for Detection of the Alligator Snapping Turtle (Macrochelys temminckii)

The alligator snapping turtle (Macrochelys temminckii) is under consideration for listing as a federally endangered species. Distributional data and estimates of population sizes are needed to make a sound decision regarding listing, but this information is largely unavailable due to the immense effort required for M. temminckii trapping surveys. To alleviate difficulty in detection and to help inform subsequent field-intensive survey efforts, we developed an environmental DNA (eDNA) method capable of providing presence data even in systems with high turbidity and suspended organic material. The assay we developed utilizes probe-based quantitative polymerase chain reaction and reliably amplifies M. temminckii eDNA in both lentic and lotic systems, with no amplification observed in other nontarget, sympatric turtle species. The novel eDNA method developed, optimized, and field-tested in this study provides a promising tool for detection of alligator snapping turtles, with resultant presence data likely to prove beneficial for the management and conservation of this species