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Updated: Jan 27, 2026
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Design and Construction of an Urban Runoff Research Facility
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Extinction vortex dynamics of top predators isolated by urbanization.
John F Benson1,2, Peter J Mahoney3, T Winston Vickers4
1School of Natural Resources, University of Nebraska, Lincoln, Nebraska, 68583, USA.
Summary
Small, isolated mountain lion populations face high extinction risk from demographic and genetic factors. Increasing habitat connectivity is crucial for their long-term survival in urbanized areas.
Area of Science:
- Conservation Biology
- Population Genetics
- Wildlife Ecology
Background:
- Small, isolated populations are vulnerable to extinction due to demographic and genetic factors.
- Population Viability Analysis (PVA) is critical for modeling these risks and informing conservation strategies.
- Urbanization poses significant threats to wildlife, fragmenting habitats and isolating populations.
Purpose of the Study:
- To conduct the first PVA for isolated mountain lions in the Santa Ana Mountains (SAM), incorporating demographic and genetic risks.
- To test how variations in abundance and mortality between SAM and Santa Monica Mountains (SMM) populations affect growth, genetic diversity, and extinction probability.
- To assess the impact of immigration and habitat connectivity on the viability of these isolated populations.
Main Methods:
- Developed Population Viability Analyses (PVA) using empirical data for two isolated southern California mountain lion populations.
- Modeled demographic and genetic factors, including population growth, extinction probability, and loss of heterozygosity.
- Simulated various scenarios, including different levels of immigration and connectivity, to evaluate population responses.
Main Results:
- Predicted a 16-21% probability of local extinction in SAM over 50 years due to demographic processes alone, without immigration.
- Projected further erosion of genetic diversity in SAM, raising concerns about inbreeding depression and potential rapid extinction.
- Observed broadly similar population dynamics between SAM and SMM, but with differences influenced by population size and mortality rates; higher immigration positively impacted viability and genetic diversity in SMM.
Conclusions:
- Demographic and genetic threats contribute to the extinction vortex in small, isolated populations.
- Habitat connectivity and land protection are essential for conserving large carnivores in urbanized landscapes.
- Simulating increased connectivity significantly reduced extinction probability, demonstrating the feasibility of conservation efforts.
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