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

Abstract

A major concern in conservation biology is toavoid inbreeding depression in smallpopulations. Inbreeding has been shown to causeloss of fecundity and reduced survival innatural populations. To predict futureinbreeding levels, given changes in ecologicalconditions, data from large outbred populationsare needed. I use recent population geneticmodels to show how genetic data from such apopulation, combined with ecological data canbe used to predict future changes in levels ofinbreeding. In particular, data from the lion(Panthera leo) is used to simulate theeffect of habitat loss on the future levels ofinbreeding. To do this I used a deterministicpopulation genetics models and anindividual-based stochastic model. Two factorsstand out as particularly important: totalnumber of prides and male dispersal rates. Ifprides are very few (= 10) inbreeding (F)will increase from 0.0 in the initial state to0.26–0.45 after 30 generations, while if thenumber of prides is 100 this level is onlyaround 0.05 assuming no migration into thepopulation. Habitat heterogeneity had onlyminor effects. A reduction in male dispersalfrom their natal territory from 100% to 95%increased the level of inbreedingsubstantially, and never reached below F≈ 0.25 regardless of the number ofprides. Therefore, to sustain a large outbredpopulation of lions, a continuous population ofat least 50 prides, but preferably 100 prides,with no limits to dispersal is required.