Northern Leopard Frogs in North Dakota: Assessing the Conservation Status of a Widespread Amphibian Species
Fisher, Justin David Lee
More InformationShow full item record
Northern Leopard Frogs in North Dakota: Assessing the Conservation Status of a Widespread Amphibian Species (1.917Mb)
North Dakota’s midcontinent location within the Prairie Pothole Region is widely known for the dense wetlands. These highly productive wetlands are mixed within an agricultural mosaic which places increased pressure on water quality and overall wetland persistence. These threats to wetlands affects other, more common species which are presumed to have healthy populations but lack statewide information. Such is the case with the northern leopard frog (Lithobates pipiens). I examined genetic variation for 41 populations across the state. Genetic diversity was not correlated with latitude, but was negatively correlated with longitude. Along this genetic diversity gradient, there was a distinctive break near the 100th meridian, a historical boundary between the arid western United States and the wet eastern side. Further data exploration revealed wetland densities to be positively correlated with genetic diversity whereas precipitation and anthropogenic disturbance were not correlated with genetic diversity. I also examined population genetic structure to identify conservation units. Strong population structuring was defined by the Missouri River, identifying the Western Badlands and Western Prairie conservation units. Further structuring of L. pipiens occurred within these two defined conservation units with rough correspondence to local watersheds. Additionally, I used approximate Bayesian computational analyses to evaluate coalescence times among the 10 defined units. The Western Prairie and Western Badlands unit shared common ancestry 13,600 to 18,100 generations ago. The coalescence times of the 6 populations within the Western Prairie unit varied from as recently as 588 generations to 10,900 generations, while populations within the Western Badlands unit varied as recently as 2,890 generations to 5,220 generations. In addition to the northern leopard frog genetics research, I conducted research that considered how sampling biases may lead to inaccurate estimates aquatic invertebrate abundance. I present an assessment of potential biases associated with sampling a population of the amphipod Gammarus lacustris in the presence of Polymorphus spp. acanthocephalan parasites shown to increase positive phototaxis in their amphipod hosts. Results indicated that the highest captures of G. lacustris individuals were in benthic traps, however, parasitized individuals were captured most often in surface traps.