title: Interactions between demography, genetics, and landscape connectivity increase extinction probability for a small population of large carnivores in a major metropolitan area.
abstract: The extinction vortex is a theoretical model describing the process by which extinction risk is elevated in small, isolated populations owing to interactions between environmental, demographic, and genetic factors. However, empirical demonstrations of these interactions have been elusive. We modelled the dynamics of a small mountain lion population isolated by anthropogenic barriers in greater Los Angeles, California, to evaluate the influence of demographic, genetic, and landscape factors on extinction probability. The population exhibited strong survival and reproduction, and the model predicted stable median population growth and a 15% probability of extinction over 50 years in the absence of inbreeding depression. However, our model also predicted the population will lose 40-57% of its heterozygosity in 50 years. When we reduced demographic parameters proportional to reductions documented in another wild population of mountain lions that experienced inbreeding depression, extinction probability rose to 99.7%. Simulating greater landscape connectivity by increasing immigration to greater than or equal to one migrant per generation appears sufficient to largely maintain genetic diversity and reduce extinction probability. We provide empirical support for the central tenet of the extinction vortex as interactions between genetics and demography greatly increased extinction probability relative to the risk from demographic and environmental stochasticity alone. Our modelling approach realistically integrates demographic and genetic data to provide a comprehensive assessment of factors threatening small populations.
authors: La Kretz Center for California Conservation, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA benson.johnf@gmail.com.
authors: John F
authors: 0000-0002-3993-4340
authors: JF
authors: Benson
authors: Department of Wildland Resources, Utah State University, Logan, UT 84231, USA.
authors: Peter J
authors: PJ
authors: Mahoney
authors: National Park Service, Santa Monica Mountains National Recreation Area, Thousand Oaks, CA 91302, USA.
authors: Jeff A
authors: JA
authors: Sikich
authors: Department of Environmental Studies, University of California, Santa Cruz, CA 95064, USA University of Cape Town, Cape Town, South Africa.
authors: Laurel E K
authors: LE
authors: Serieys
authors: Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA.
authors: John P
authors: JP
authors: Pollinger
authors: Department of Veterinary Science, University of Wyoming, Laramie, WY 82070, USA.
authors: Holly B
authors: HB
authors: Ernest
authors: La Kretz Center for California Conservation, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA National Park Service, Santa Monica Mountains National Recreation Area, Thousand Oaks, CA 91302, USA Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA.
authors: Seth P D
authors: SP
authors: Riley
mesh_terms: D000818:Animals; D005828:Genetics, Population; D015141:Los Angeles; D011157:Population Dynamics; D011336:Probability; D046011:Puma / Q000235:genetics*
keywords: PVA; Puma concolor; demographic stochasticity; heterozygosity; immigration; inbreeding depression