Unidirectional Introgression and Evidence of Hybrid Superiority over Parental Populations in Eastern Iranian Plateau Population of Hares (Mammalia: Lepus Linnaeus, 1758)

Abstract

Hares from Iran can be divided into three morphological groups, with Lepus europaeus inhabiting the western parts of Iran. Hares from lowland areas along the southeastern corner of the Caspian Sea are morphologically similar to both L. tolai and L. tibetanus, but diagnosis is complicated by a lack of taxonomic agreement. Mitochondrial DNA suggests L. tibetanus rather than L. tolai, although comparative material is not incontestable. The third group, in more xeric habitats of eastern Iran, shows a mixture of traits characteristic of both the west Iranian L. europaeus and the Golestan population, the southeast Caspian Sea. Mitochondrial and nuclear loci reveal conflicting patterns, where hares from eastern Iran cluster with L. europaeus based on mtDNA, but with the Golestan population based on nuclear transferrin, suggesting a mixed ancestry. Ecological niche modeling indicates that the preferred habitat of the Golestan population is more restricted than that of the other two groups. Pure L. europaeus occur in areas of high seasonality, low temperature, and high precipitation, whereas the population in eastern Iran inhabits areas characterized by high contrast in daily temperatures and the highest isothermality in eastern Iran. Parts of the range of this population are also indicated to correspond to the fundamental niche of L. europaeus, yet both parental forms appear to be absent from this area occupied by individuals of apparent mixed ancestry. This suggests that the population of mixed ancestry may have selective advantages over the parental forms, and that the absence of the latter from this area may be due to competitive exclusion. As the population of mixed ancestry thus appears to be self-sustaining, incipient speciation of a stabilized hybrid may be implied.