Phylogeography of widespread species in Eurasia: Current progress and future prospects

Abstract

The geographical distribution patterns of the widespread species in Eurasia are classified into four major categories: global distribution, holarctic distribution, mid-high latitude Eurasian distribution, and mid-low latitude Eurasian distribution patterns. By comparing the results of recent phylogeographic studies on the widespread species in Eurasia, we have outlined three phylogeographic patterns: (i) “single-component,” (ii) “east-west component,” and (iii) “peripatric component” patterns. The present study summarizes the factors that potentially influence the phylogeographic patterns of the widespread species in Eurasia. These factors include the following: (i) the relatively high environmental tolerance and dispersal ability of the species as well as the influence of human trade, transportation, and domestication activities; (ii) the east-west diverging Pleistocene glacial climate and the inland arid belt: during glaciation, most regions of Europe were covered with ice sheets; therefore, the species retreated to refuge areas and during the interglacial periods, they recolonized to suitable areas, which facilitated survival after the Last Glacial Maximum. The glacial climates in most parts of Asia were relatively mild, particularly in east Asia, which was less extensively glaciated, as a result of which the glacial period had a relatively low impact on the distribution patterns of species in such areas. In addition, the rapid uplift of the Qinghai-Tibetan Plateau during the Pleistocene and the intensification of the Asian summer monsoon have promoted the formation of the inland arid belt of Eurasia, resulting in long-term ecological isolation. Lastly, (iii) the influence of peripatric speciation: populations disperse to the new marginal environment. Due to geographic or environmental isolation, genetic drift is fixed in small isolated populations, resulting in genetic differentiation among populations. Analyzing the unique and consistent response mechanisms of the widespread species in Eurasia under similar geographical and geological histories would facilitate our understanding of the mechanisms underlying the establishment of geographical populations of the widely distributed species in Eurasia. In addition, this will summarize and identify appropriate diversities and universal principles influencing the phylogeographical patterns of the Eurasian species. Finally, the present study reveals prospective research directions in phylogeography on the widespread species in Eurasia based on large-scale nuclear genome markers and the integration of life history traits into predictive phylogeography.