Interaction between range expansion and genetic structure in a reintroduced wild ass population

Progress Report: BSF Grant 2009296 PI’s: Shirli Bar-David, Alan R. Templeton Title: Interaction between range expansion and genetic structure in a reintroduced wild ass population and implications for conservation This study aims to explore the interaction between two parallel processes occurring within a colonizing population: (i) the population's range expansion and (ii) the development of population genetic structure. By an inter-disciplinary approach that combines field surveys, genetic analyses and modeling, we study the reintroduced wild ass (Equus hemionus) population in the Negev desert as a model system. Here we report the results of our study in the context of our original aims.

The population's range expansion: We mapped the spatial distribution of the reintroduced wild ass in the Negev Desert, based on an intensive field survey followed by spatial analyses using GIS, and identified the main population activity centers in the area. We further constructed a MAXENT-type spatial probability model for E. hemionus, which enabled us to deduce the wild ass spatial habitat preferences and the main factors affecting its distribution. These findings can be used as a foundation for assessing future spatial distribution of this species and for locating areas that should be conserved for species’ persistence.

The population genetic structure: We evaluated and developed markers for the genetic study of E. hemionus. We designed an original factorial experiment to explore the effect of several non-invasive genetic methods on the quality of DNA obtained from E. hemionus feces collected in the field (non-invasive sampling). The results were published in Animal Conservation. We analyzed 30 blood samples of the founders of the reintroduced population and 393 fecal samples of the wild population. Although the three different mtDNA haplotypes of the founders maintained in the wild populations, a significant genetic difference between the founders and the wild population was observed (Fst= 0.104, P

The interaction between the population's range of expansion and genetic structure: We analyzed the fecal samples collected in the field, and grouped them according to their geographical locations, using GIS. Samples collected in the 'Eastern region' of the population's range of distribution were significantly genetically different from samples from other regions (pairwise Fst, SAMOVA). This genetic structure could be related to the high quality habitat in the Eastern region, which is relatively isolated from other regions. We suggest that the 'Eastern subpopulation' was initiated following a founder effect of individuals that disperse from the reintroduction site and remained in the 'new area' due to its habitat quality. Long-term monitoring is needed in order to observe the dynamics of this genetic structure throughout time.