Phylogeography of Potamon ibericum (Brachyura: Potamidae) identifies Quaternary glacial refugia within the Caucasus biodiversity hot spot

Abstract

Refugia are critical for the maintenance of biodiversity during the periods of Quaternary climatic oscillations. The long‐term persistence of refugial populations in a large continuous refugium has resulted in a homogenous pattern of genetic structure among populations, while highly structured evolutionary lineages characterize the restriction of refugial populations to smaller subrefugia. These mechanisms have resulted in the identification of hot spots of biodiversity within putative glacial refugia. We studied phylogeography of Potamon ibericum (Brachyura: Potamidae) in the drainages of the western Caucasus biodiversity hot spot (i.e., Colchis and the Caucasus) to infer spatial genetic structure and potential refugia for a freshwater crab in this region. These areas have traditionally considered as a refugium due to the presence of Tertiary relict species. We integrated population genetic data and historical demographic analysis from cytochrome oxidase subunit I sequences and paleoclimatic data from species distribution modeling (SDM). The results revealed the lack of phylogeographic structure and provided evidence for demographic expansion. The SDM presented a rather homogenous and large refugium that extended from northeast Turkey to Colchis during the last glacial period. In contrast to these findings, previous phylogeographic study on P. ibericum of the eastern Caucasus biodiversity hot spot (i.e., Hyrcania) identified multiple independent refugia. By combining these results, we explain the significance of this important western Palearctic hot spot of biological diversity in shaping the geographic distribution of intraspecific genetic diversity in a freshwater taxon.

Evidence of an additional centre of apple domestication in Iran, with contributions from the Caucasian crab apple Malus orientalis Uglitzk. to the cultivated apple gene pool

“…Additional samples from the Western Caucasus are required to confirm this hypothesis. These glacial refugia have been described in relation to other species(Parvizi et al, 2019). Indeed, two refugia are recognized in the Caucasus(Aradhya et al, 2017;Bina et al, 2016;Tarkhnishvili et al, 2012;Yousefzadeh et al, 2012): a major forest refugium between the western Lesser Caucasus and northeastern Turkey (including the Colchis region in the catchment basin of the Black Sea) and the Hyrcanian refugium at the southern edge of the Caucasus.Further sampling of M. orientalis in the far Western and Eastern Caucasus and genotyping with the same microsatellite markers are needed to uncover the role of these two refugia in the divergence history of M. orientalis.…”

Evidence of an additional wild contributor, Malus orientalis Uglitzk., to the genome of cultivated apple varieties in the Caucasus and Iran

“…Ecological niche modeling also suggested that the Caucasian wild apple restricted its range to the Colchis region and the Higher Caucasus Mountains, bordering the Black Sea, and the Eastern Caucasus close to Azerbaijan, but we lacked samples from these regions to further confirm this hypothesis. These glacial refugia have been described in relation to other species (Parvizi et al ., 2019). Indeed, in the Caucasus, two refugia are recognized (Tarkhnishvili et al .…”

“…Additional samples from the Western Caucasus are required to confirm this hypothesis. These glacial refugia have been described in relation to other species (Parvizi et al, 2019). Indeed, two refugia are recognized in the Caucasus (Tarkhnishvili et al 2012; Yousefzadeh et al 2012; Bina et al 2016; Aradhya et al 2017): a major forest refugium between the western Lesser Caucasus and northeastern Turkey (including the Colchis region in the catchment basin of the Black Sea) and the Hyrcanian refugium at the southern edge of the Caucasus.…”

“…Ecological niche modeling also suggested that the Caucasian wild apple restricted its range to the Colchis region and the Higher Caucasus Mountains, bordering the Black Sea, and the Eastern Caucasus close to Azerbaijan, but we lacked samples from these regions to further confirm this hypothesis. These glacial refugia have been described in relation to other species (Parvizi et al, 2019). Indeed, in the Caucasus, two refugia are recognized (Tarkhnishvili et al 2012;Yousefzadeh et al 2012;Bina et al 2016;Aradhya et al 2017): a major forest refugium between the western Lesser Caucasus and northeast Turkey (including the Colchis region in the catchment basin of the Black Sea) and the Hyrcanian refugium at the southern edge of the Caucasus.…”

Genetic homogeneity in a Pontocaspian crested newt species (Triturus karelinii) suggests recent isolation of its three allopatric range sections

“…The species distribution model suggests that both the Caucasian and the Caspian range sections acted as glacial refugia for T. karelinii. For other Pontocaspian taxa the region along the southern Caspian Sea coast, north of the Elburz mountains and/or the Colchis in western Caucasia have been predicted as glacial refugia as well (Leroy and Arpe, 2007;Tarkhnishvili et al, 2012;Dufresnes et al, 2016;van Riemsdijk et al, 2017;Parvizi et al, 2019).…”