Fenced and Fragmented: Conservation Value of Managed Metapopulations

Abstract

Population fragmentation is threatening biodiversity worldwide. Species that once roamed vast areas are increasingly being conserved in small, isolated areas. Modern management approaches must adapt to ensure the continued survival and conservation value of these populations. In South Africa, a managed metapopulation approach has been adopted for several large carnivore species, all protected in isolated, relatively small, reserves that are fenced. As far as possible these approaches are based on natural metapopulation structures. In this network, over the past 25 years, African lions (Panthera leo) were reintroduced into 44 fenced reserves with little attention given to maintaining genetic diversity. To examine the situation, we investigated the current genetic provenance and diversity of these lions. We found that overall genetic diversity was similar to that in a large national park, and included a mixture of four different southern African evolutionarily significant units (ESUs). This mixing of ESUs, while not ideal, provides a unique opportunity to study the impact of mixing ESUs over the long term. We propose a strategic managed metapopulation plan to ensure the maintenance of genetic diversity and improve the long-term conservation value of these lions. This managed metapopulation approach could be applied to other species under similar ecological constraints around the globe.

Fencing Africa's protected areas: Costs, benefits, and management issues

“…Alternatively, the impacts of fragmentation could be reduced by facilitating the movement of individual animals between PAs to mimic natural dispersal patterns (Davies-Mostert et al 2009;Miller et al 2015;Buk et al in press). Examples of such "managed metapopulations" include black rhinos (Brooks 1989;Foose et al 1993) and white rhinos (Emslie et al 2009) in Southern and East Africa and wild dogs in South Africa (Mills et al 1998;Davies-Mostert 2010).…”

Spatiotemporal Genetic Diversity of Lions

“…Knowing that population structure has been found regionally (28,30,33,37,40,71,72), we implemented a hierarchical strategy to uncover any hidden structure that may be lost when subpopulations are analyzed together (73)(74)(75). STRUCTURE runs were performed on each of the full MD and HD datasets without priors for 15 iterations of K 1-15 for 100,000 MCMC reps with 10% burn in.…”

‘Intentional Genetic Manipulation’ as a conservation threat

“…Zoo populations are carefully managed to alleviate small population problems, with frequent transfer of individuals for mating (Lacy 2013). Scientists and wildlife ranchers should be encouraged to codevelop metapopulation and population management plans for each species, as has been done for wild dogs, lions and other predators (Miller et al 2015). This may, for example, include guidelines for the number of individuals needed to be translocated to maintain genetically healthy populations after taking into account the costs and benefits.…”