Resource management as a conservation tool to impact genetic diversity through mating patterns in wild populations

The distribution of resources influences interactions in wild populations by affecting movement, space-use patterns, and, as a result, mating systems. Limited resources may reduce encounters between potential breeders, reducing the number and variety of individuals contributing to the population's gene pool. This can impact the variance effective population size (N_ev), an important indicator of genetic drift and genetic diversity in populations. Despite its importance, the relationship between resource distribution and genetic diversity has received limited attention in the practical management of genetically vulnerable populations. Here, we provide empirical evidence that the number of reproducing males (adult males identified as sires by parentage analysis from foal genotypes) and N_ev can be affected by resource management in the population of the Asiatic wild ass (Equus hemionus) in the Negev Desert, Israel, using water sources. This population, characterized by strong polygyny, has experienced declining genetic diversity. Following an intervention to increase the number of water sources from one to three during May 2020, we monitored the population using noninvasive genetic methods and direct observations. We collected 864 fecal samples from adult males, females, and foals, genotyped the DNA across 535 single nucleotide polymorphisms (SNPs), and conducted a parentage analysis. The results showed an increase in the proportion of total reproducing males out of all adult males in the population from 16%-18% to 42%-48%, with a significant rise in reproducing males in 2020 that had not been sires in 2019, from 31.2% to 73.8% (Z = -2.877, p = 0.002) before and after the management, respectively. Spatial analyses indicated a higher presence of reproducing males near the new water sources. These findings demonstrate how resource management can impact N_ev in the short term and, therefore, potentially influence genetic diversity in the long term. We suggest a management framework targeting genetic diversity within an adaptive management approach and discuss its relevance and applicability for other systems and types of resources.