Consequences of the Last Glacial Period on the Genetic Diversity of Southeast Asians.

Marina Kanellou,Catarina Branco,Miguel Arenas,Antonio González-Martín

doi:10.3390/genes13020384

Abstract

The last glacial period (LGP) promoted a loss of genetic diversity in Paleolithic populations of modern humans from diverse regions of the world by range contractions and habitat fragmentation. However, this period also provided some currently submersed lands, such as the Sunda shelf in Southeast Asia (SEA), that could have favored the expansion of our species. Concerning the latter, still little is known about the influence of the lowering sea level on the genetic diversity of current SEA populations. Here, we applied approximate Bayesian computation, based on extensive spatially explicit computer simulations, to evaluate the fitting of mtDNA data from diverse SEA populations with alternative evolutionary scenarios that consider and ignore the LGP and migration through long-distance dispersal (LDD). We found that both the LGP and migration through LDD should be taken into consideration to explain the currently observed genetic diversity in these populations and supported a rapid expansion of first populations throughout SEA. We also found that temporarily available lands caused by the low sea level of the LGP provided additional resources and migration corridors that favored genetic diversity. We conclude that migration through LDD and temporarily available lands during the LGP should be considered to properly understand and model the first expansions of modern humans.

Highlights

Despite intense efforts for understanding the evolutionary history of early modern humans (EMHs), diverse past evolutionary events are still unclear
In order to understand the consequences of the last glacial period (LGP) on the genetic diversity of current Southeast Asia (SEA) populations, here we evaluated the fitting of four alternative evolutionary scenarios, which either consider or ignore the LGP and long-distance dispersal (LDD), with observed genetic data from a variety of SEA populations
Here we explored whether the temporarily available lands derived from the lowering sea level caused by the LGP, together with LDD, influenced the expansion of EMHs throughout SEA, and if they are required to understand the currently observed genetic patterns in this region

Summary

Introduction

Despite intense efforts for understanding the evolutionary history of early modern humans (EMHs), diverse past evolutionary events are still unclear. One of them involves the genetic consequences of environmental conditions that occurred during the first expansion of our species In this regard, the last glacial period (LGP; 125,000–11,000 years ago (ya)). Produced large ice sheets in the northern hemisphere regions and increased the extension of deserts [1], forcing humans (as well as other species) to migrate toward more suitable regions and reduce their genetic diversity [2]. These range contractions and range shifts, usually by reducing and moving their living ranges toward lower latitude regions, reduced the genetic diversity in the populations [3,4]. The LGP produced a negative impact on human genetic diversity through range contractions [2,3]

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Conclusion