The risk of inbreeding due to habitat loss in the lion (Panthera leo)

A major concern in conservation biology is to avoid inbreeding depression in small populations. Inbreeding has been shown to cause loss of fecundity and reduced survival in natural populations. To predict future inbreeding levels, given changes in ecological conditions, data from large outbred populations are needed. I use recent population genetic models to show how genetic data from such a population, combined with ecological data can be used to predict future changes in levels of inbreeding. In particular, data from the lion (Panthera leo) is used to simulate the effect of habitat loss on the future levels of inbreeding. To do this I used a deterministic population genetics models and an individual-based stochastic model. Two factors stand out as particularly important: total number of prides and male dispersal rates. If prides are very few (= 10) inbreeding (F) will increase from 0.0 in the initial state to 0.26-0.45 after 30 generations, while if the number of prides is 100 this level is only around 0.05 assuming no migration into the population. Habitat heterogeneity had only minor effects. A reduction in male dispersal from their natal territory from 100% to 95% increased the level of inbreeding substantially, and never reached below F approximate to 0.25 regardless of the number of prides. Therefore, to sustain a large outbred population of lions, a continuous population of at least 50 prides, but preferably 100 prides, with no limits to dispersal is required.