Evaluation of the genetic viability of metapopulation scenarios for the Iberian lynx

Abstract

The Iberian lynx has shown a favourable demographic trajectory in the last decade as a result of the conservation measures adopted which are still ongoing. However, the viability of the species is still compromised by genetic factors. Here, we used the GESP software that predicts the effective population size (Ne) and inbreeding accumulation (∆f) over time in metapopulations, to find realistic scenarios that guarantee the genetic viability of this species. We proposed as genetic targets that Ne of the metapopulation (Ne_Meta) should exceed 500 in 20 generations (long term), whereas ∆f of the subpopulations (∆f_x) should not exceed 0.05 in five generations (short term). The current Iberian lynx metapopulation configuration, with the expected subpopulations sizes at carrying capacity (5 subpops.; Ne₁ = 100, Ne_2,3,4,5 = 25), does not reach the long-term goal, with a Ne_Meta ~ 150 in 20 generations. The results indicate that the long-term genetic viability of the metapopulation requires an increase in the subpopulation size of 50–200%, the creation of at least 8 new subpopulations, and migration rates close to 0.1 between neighbouring subpopulations, comprising 2165 effective individuals (ca. 1100 breeding females). In addition, a minimum migration rate of 0.05 into the smallest subpopulations of Ne = 25 (i.e. 1.25 migrants/generation) is needed to avoid excessive inbreeding accumulation (short-term goal). Larger subpopulations are preferable to several smaller subpopulations with the same number of effective individuals, even when the latter are well connected. Although these requirements seem challenging to achieve in the short-medium term, the study provides key information for informed decision making by environmental managers and policymakers. The conclusions drawn here apply to other carnivores in need of conservation.