Data from: Demographic, genetic and landscape interactions increase extinction probability in a small population of large carnivores in a major metropolitan area

The extinction vortex is a theoretical model describing the process by which extinction risk is elevated in small, isolated populations due to interactions between environmental, demographic, and genetic factors. However, empirical demonstrations of these interactions have been elusive. We modeled 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 ≥1 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 modeling approach realistically integrates demographic and genetic data to provide a comprehensive assessment of factors threatening small populations.