科研之友
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摘要
Domestic pigs were first introduced to California by Spanish explorers and missionaries in the 1700s and were soon established as feral populations in coastal regions. Feral pigs are currently abundant in mainland California where their presence in 56 of the state's 58 counties is ecologically problematic. We used molecular techniques to inform on an incomplete record of human introductions associated with escape or purposed release of domestic and European-type wild swine in California, and to provide insight on the mechanisms that produced an accelerated expansion dynamic in the state after the 1970s. We developed mtDNA sequence data for 151 tissue or blood samples from wild pigs spanning their distribution in California, and a 550 base pair segment of the control region was used in phylogenetic analysis. Phylogenetic analyses included our data and 904 published sequences for wild and domestic swine from elsewhere in the U.S. and around the world. Gene flow indicative of natural spread in California was assessed from population-level mtDNA sequence relationships for five population groupings, and we assessed mtDNA haplotypes associated with different periods of invasion by partitioning samples originating from "Historic" occupied counties (before 1968), and "Recent" occupied counties. Nine mtDNA haplotypes were identified among wild pigs California, including three that were unique to California, three that were common elsewhere in the United States, two that were known from Hawaii or other Pacific Islands, and one that was known only from Kentucky, USA. Apparent gene flow between Recent and Historic ranges indicated that pigs dispersed at the regional level, and we identified evidence for expansion by anthropogenic and natural processes from presence of several haplotypes only in Recent range. MtDNA sequence data provided new insight on wild pig expansion in California, including evidence that contemporary translocations promoted hybridization and subsequent spread by natural population growth. Considered together, information on the distribution of common and unique haplotypes and gene flow suggests that range expansion by wild pigs in California is progressing by natural and human-facilitated dispersal, and new introductions from outside of the state. We advocate against additional anthropogenic movement of wild pigs within the state or from other U. S. states because these animals are known to be detrimental to native plants and animals in California ecosystems.
- 出版日期2015
