Phylogeographic Patterns Are Strongly Associated With Biogeographic Patterns in the Irano-Anatolian Global Biodiversity Hotspot.

Biogeographic breaks, that is, shifts in overall species composition, are expected to be associated with phylogeographic breaks because of shared ecological or evolutionary factors operating at both the interspecific and intraspecific level. Here, we test the hypothesis that biogeographic and phylogeographic boundaries are congruent using mountain species of the Iranian Plateau as our model system. To this end, we analysed the genetic structure from RAD-sequencing data of four montane (i.e., mid-elevation) and five alpine plant species endemic to yet widely distributed in the Iranian mountains. Phylogeographic boundaries (breaks) were inferred via the Monmonier maximum difference algorithm and compared to biogeographic breaks identified previously based on floristic data. Major phylogeographic break zones, supported by several montane and alpine species, were identified between Alborz and Zagros as well as between the Azerbaijan Plateau and Zagros (each of those areas corresponding to an area of endemism), thus supporting the biogeography and phylogeography concordance hypothesis. Deviations from this pattern of congruence between biogeographic and phylogeographic breaks mostly concern the presence of additional phylogeographic breaks within areas of endemism. Moreover, the genetic structure is stronger in alpine than in montane species, which can at least partly be attributed to the stronger isolation of high-elevation habitats acting as sky islands.