Date of Award

8-11-2008

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

First Advisor

Richard A. Sweitzer

Abstract

This study describes this historic origin, recent range expansion, and a generalized habitat suitability model for wild pigs (Sus scrofa ) in California. The genetic origins of wild pigs in California was determined to be of European and Asian descent by comparing published mitochondrial DNA (mtDNA) sequence data from European and Asian wild and domestic pigs with 107 wild pig mtDNA sequences from California. Based on the clustering of mtDNA genotypes, the recent range expansion of wild pigs in California was a function of both natural range expansion and multiple hunter related introductions. Analysis of the range expansion of wild pigs in California was done using 14 years of hunter returned pig-tag data and wild pig depredation permit records. These wild pig removal records were divided into three periods for each of California's 10 ecoregions (period 1: 1992-1998; period 2: 1998-2002; period3: 2002-2006). Comparisons among these three periods indicated that the range of wild pigs increased throughout the state except in the northwest California. The most significant range expansion has occurred in the central valley region, likely related to agricultural practices. Results indicated that hunter control of wild pig populations was effective in some areas of the state with public access to hunting, whereas other areas with limited hunting access were identified as experiencing continued spread of the species. Development of a generalized habitat suitability model for wild pigs in California was done using statewide land cover spatial data. This model was validated through regression analysis using wild pig distribution data from both hunter returned pig tags and depredation permit records from the central coast region of California. The model performed well (p < 0.001) at predicting both abundance and occupancy of wild pigs in this region. The model identified 32.5% (132,752 km2) of the area of California as suitable wild pig habitat. The model also identified > 51,000 km 2 not currently occupied by wild pigs that may become occupied in the future.

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