Source-Sink Dynamics and Individual Variation in Prey Selection and Habitat Selection of Mountain Lions in the Great Basin of Nevada
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Authors
Andreasen, Alyson M.
Issue Date
2014
Type
Dissertation
Language
Keywords
Great Basin , Lake Tahoe , large carnivore , mountain lion , Puma concolor , wild horse
Alternative Title
Abstract
ABSTRACT: The mountain lion (Puma concolor) is the widest ranging extant mammal in the Americas. While the history of the mountain lion since the arrival of Europeans in North America is one of strife, the mountain lion has proved highly resilient despite political polarization, continued persecution, and habitat loss throughout much of its current range. My dissertation research was the first research to be conducted on mountain lions in Nevada since the 1970s despite being shrouded in controversy in the state. Therefore, my dissertation research addressed a broad set of questions pertaining to the ecology of mountain lions in Nevada and is organized into 3 main chapters.In chapter 2, I used recently developed genetic techniques to assess population genetic structure and source-sink dynamics of mountain lions at the landscape scale. I analyzed thirteen microsatellite loci for 739 mountain lions using muscle tissue samples from individuals in the Great Basin, throughout Nevada, and the Sierra Nevada mountain range in eastern California. I tested the hypothesis that heterogeneous hunting pressure results in source-sink dynamics at the landscape scale. I used a combination of non-spatial and spatial model-based Bayesian clustering methods to identify genetic populations. I then used a recently developed Bayesian multilocus genotyping method to estimate asymmetrical rates of contemporary movement between those subpopulations and to identify source and sink populations.Two populations were identified at the highest level of genetic structuring with a total of 5 subpopulations in the Great Basin of Nevada and the Sierra Nevada range. Results suggest that source-sink dynamics occur at landscape scales for mountain lions, and that source populations may be those that are under relatively less hunting pressure because they occupy refugia. In my 3rd chapter, I examined the incidence of prey specialization of mountain lions in the western Great Basin and eastern Sierra Nevada. I tested hypotheses pertaining to the degree of individual specialization and diet overlap in areas with varying abundances and types of prey. Mountain lions increased variation among individual diets where primary prey was limited but ecological opportunity existed; in areas of low availability of total prey, however, all individuals had generalist foraging strategies. In areas of the Great Basin, a novel food item - feral horses - provided ecological opportunity for prey specialization.In chapter 4, I modeled habitat selection of mountain lions in the western Great Basin and eastern Sierra of Nevada and accounted for risk of human caused mortality across the landscape to highlight potential localized population sinks. Results suggest that high quality habitat for mountain lions in our study area is substantially less than expected once risk of human caused mortality is considered. In addition, after risk of mortality is included, mountain ranges with low proportions of high quality habitat within the Great Basin can contain equal amounts of high quality habitat compared to areas within the Sierra Nevada, a region of generally higher quality habitat. Based on area requirements of mountain lions and mortality of study animals, the results suggest that at the confluence of the Sierra and Great Basin Desert, areas where human-caused mortality is predicted to be low are not large enough to provide actual refuge for mountain lions. My research has linked theoretical and empirical approaches in ecology and conservation to address important issues in the conservation and management of mountain lions. The results have led to a greater understanding of population genetic structure, source-sink dynamics, habitat selection and individual prey specialization at multiple scales for mountain lions. These results also have broad implications for the conservation and management of other large vagile mammals; particularly those impacted by humans and human altered landscapes.
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In Copyright(All Rights Reserved)