SREL Reprint #3547

Invasion ecology of wild pigs (Sus scrofa) in Florida, USA: the role of humans in the expansion and colonization of an invasive wild ungulate

Felipe A. Hernández1,2, Brandon M. Parker2, Cortney L. Pylant2, Timothy J. Smyser3, Antoinette J. Piaggio3, Stacey L. Lance4, Michael P. Milleson5, James D. Austin1,2, and Samantha M. Wisely1,2

1School of Natural Resources and Environment, University of Florida, 103 Black Hall,
PO Box 116455, Gainesville, FL 32611, USA
2Department of Wildlife Ecology and Conservation, University of Florida, 110 Newins-Ziegler Hall,
PO Box 110430, Gainesville, FL 32611, USA
3United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services,
National Wildlife Research Center, 4101 LaPorte Avenue, Fort Collins, CO 80521, USA
4Savannah River Ecology Laboratory, University of Georgia, PO Drawer E, Aiken, SC 29802, USA
5United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, 2820 East University Avenue, Gainesville, FL 32641, USA

Abstract: Wild pigs (Sus scrofa) are the most widely distributed invasive wild ungulate in the United States, yet the factors that influence wild pig dispersal and colonization at the regional level are poorly understood. Our objective was to use a population genetic approach to describe patterns of dispersal and colonization among populations to gain a greater understanding of the invasion process contributing to the expansion of this species. We used 52 microsatellite loci to produce individual genotypes for 482 swine sampled at 39 locations between 2014 and 2016. Our data revealed the existence of genetically distinct subpopulations (FST = 0.1170, p<0.05). We found evidence of both fine-scale subdivision among the sampling locations, as well as evidence of long term genetic isolation. Several locations exhibited significant admixture (interbreeding) suggesting frequent mixing of individuals among locations; up to 14% of animals were immigrants from other populations. This pattern of admixture suggested successive rounds of human-assisted translocation and subsequent expansion across Florida. We also found evidence of genetically distinct populations that were isolated from nearby populations, suggesting recent introduction by humans. In addition, proximity to wild pig holding facilities was associated with higher migration rates and admixture, likely due to the escape or release of animals. Taken together, these results suggest that human-assisted movement plays a major role in the ecology and rapid population growth of wild pigs in Florida.

Keywords: Invasion ecology; Sus scrofa; Florida; Human-assisted movement; Interbreeding; Immigration

SREL Reprint #3547

Hernandez, F. A., B. M. Parker, C. L. Pylant, T. J. Symyser, A. J. Piaggio, S. L. Lance, M. P. Milleson, J. D. Austin, and S. M. Wisely. 2018. Invasion ecology of wild pigs (Sus scrofa) in Florida, USA: the role of humans in the expansion and colonization of an invasive wild ungulate. Biological Invasions 20(7): 1865-1880.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).