Bison phylogeography constrains dispersal and viability of the Ice Free Corridor in western Canada

Abstract

The Ice Free Corridor has been invoked as a route for Pleistocene human and animal dispersals between eastern Beringia and more southerly areas of North America. Despite the significance of the corridor, there are limited data for when and how this corridor was used. Hypothetical uses of the corridor include: the first expansion of humans from Beringia into the Americas, northward postglacial expansions of fluted point technologies into Beringia, and continued use of the corridor as a contact route between the north and south. Here, we use radiocarbon dates and ancient mitochondrial DNA from late Pleistocene bison fossils to determine the chronology for when the corridor was open and viable for biotic dispersals. The corridor was closed after ∼23,000 until 13,400 calendar years ago (cal y BP), after which we find the first evidence, to our knowledge, that bison used this route to disperse from the south, and by 13,000 y from the north. Our chronology supports a habitable and traversable corridor by at least 13,000 cal y BP, just before the first appearance of Clovis technology in interior North America, and indicates that the corridor would not have been available for significantly earlier southward human dispersal. Following the opening of the corridor, multiple dispersals of human groups between Beringia and interior North America may have continued throughout the latest Pleistocene and early Holocene. Our results highlight the utility of phylogeographic analyses to test hypotheses about paleoecological history and the viability of dispersal routes over time.

Underwater faunal assemblages: radiocarbon dates and late Quaternary vertebrates from Cold Lake, Alberta and Saskatchewan, Canada

“…The age is consistent 633 with the Quaternary record of western Canada as a whole, where early post-LGM records of bison are 634 widely reported in the literature (e.g., Wilson et al 2008;Heintzman et al 2016), and the record 635 provides insight into the sparse faunal history of east-central Alberta and west-central Saskatchewan. 636…”

A middle Holocene steppe bison and paleoenvironments from the Versleuce Meadows, Whitehorse, Yukon, Canada

“…Populations of elk, bison, and caribou locally survived in Yukon through this period of dramatic ecological turmoil and remained in the Subarctic and Arctic through much of the Holocene. Fossil and ethnohistorical evidence demonstrates that native bison populations in Yukon were regionally extirpated roughly 400 years ago (Stephenson et al 2001;Heintzman et al 2016). Present day populations of elk and wood bison (B. bison athabascae) are now common in the boreal forest of southern Yukon and are the result of human-mediated reintroductions during the mid-20th century.…”

“…Genetic studies based on mitochondrial DNA from Quaternary bison have shown that extant bison, B. bison, arose during the last glacial maximum from ancestors situated south of the continental ice sheets, and that B. bison mitochondrial variation falls within a much more diverse bison complex (including the steppe bison, B. priscus) that occurred both north and south of the ice sheets during the late Pleistocene (Shapiro et al 2004;Heintzman et al 2016;Froese et al 2017). As mitochondrial DNA sequences can distinguish B. bison from other bison taxa, they can be used to infer the systematic status and phylogeographic history of enigmatic bison specimens.…”

In the light of evolution X: Comparative phylogeography

“…In a phylogeographic study of North American bison, Peter Heintzman et al (31) advocate for a greater emphasis on paleoecology as a major driving force shaping contemporary phylogeographic patterns. Their example involves the purported role of an Ice Free Corridor as a plausible route for dispersal (of humans and other animals) between Beringia and more southerly areas of North America.…”

“…This general topic has already been addressed by several of the colloquium papers. For example, Bowen et al (19) explicitly link modern marine phylogeography to traditional biogeographic perspectives on biodiversity in the sea; Wakeley et al (23), Mehta et al (24), and others relate phylogeography to historical population demography, coalescent theory, and traditional population genetics; Edwards et al (27) explicitly weighed and contrasted comparative phylogeography with molecular phylogenetics and phylogenomics; Heintzman et al (31) and Prates et al (21), among others, advocated the incorporation of more paleoecology into phylogeography; and several authors touched upon the special relevance of phylogeographic findings for the field of conservation biology. The final paper in this colloquium provides one further example of how comparative phylogeography relates to yet another emerging biodiversity field.…”