Past climate changes, population dynamics and the origin of Bison in Europe

Abstract

BackgroundClimatic and environmental fluctuations as well as anthropogenic pressure have led to the extinction of much of Europe’s megafauna. The European bison or wisent (Bison bonasus), one of the last wild European large mammals, narrowly escaped extinction at the onset of the 20th century owing to hunting and habitat fragmentation. Little is known, however, about its origin, evolutionary history and population dynamics during the Pleistocene.ResultsThrough ancient DNA analysis we show that the emblematic European bison has experienced several waves of population expansion, contraction, and extinction during the last 50,000 years in Europe, culminating in a major reduction of genetic diversity during the Holocene. Fifty-seven complete and partial ancient mitogenomes from throughout Europe, the Caucasus, and Siberia reveal that three populations of wisent (Bison bonasus) and steppe bison (B. priscus) alternately occupied Western Europe, correlating with climate-induced environmental changes. The Late Pleistocene European steppe bison originated from northern Eurasia, whereas the modern wisent population emerged from a refuge in the southern Caucasus after the last glacial maximum. A population overlap during a transition period is reflected in ca. 36,000-year-old paintings in the French Chauvet cave. Bayesian analyses of these complete ancient mitogenomes yielded new dates of the various branching events during the evolution of Bison and its radiation with Bos, which lead us to propose that the genetic affiliation between the wisent and cattle mitogenomes result from incomplete lineage sorting rather than post-speciation gene flow.ConclusionThe paleogenetic analysis of bison remains from the last 50,000 years reveals the influence of climate changes on the dynamics of the various bison populations in Europe, only one of which survived into the Holocene, where it experienced severe reductions in its genetic diversity. The time depth and geographical scope of this study enables us to propose temperate Western Europe as a suitable biotope for the wisent compatible with its reintroduction.Electronic supplementary materialThe online version of this article (doi:10.1186/s12915-016-0317-7) contains supplementary material, which is available to authorized users.

The Year of the Wisent

“…One surprising finding in both studies is the existence of two distinct wisent subpopulations, one being the ancestor of the current population and the other representing an extinct subspecies called ‘CladeX’ [2] or ‘Bb1’ [1]. Both studies also show that the population size of the wisent and steppe wisent fluctuated during the period of successive glaciations.…”

“…1) and with the ancestors of the cattle we later domesticated. The eventful history of the wisent is now being reconstructed by several research groups, but the quest to pin down its ancestry has produced conflicting answers [1, 2].

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“…Two recent multi-author papers [1, 2] have successfully met the challenge of capturing and sequencing DNA from ancient wisent samples in order to reconstruct their ancestry. These reports were preceded by two other studies of the origin of the wisent [3, 4], also with large molecular datasets, state-of-the-art analyses and logical interpretations.…”

“…The two most recent studies [1, 2], however, dig much deeper into the wisent past [4, 5]. Both describe a large aDNA dataset covering a wide geographic range, with the oldest samples dated more than 50,000 years ago.…”

“…Both describe a large aDNA dataset covering a wide geographic range, with the oldest samples dated more than 50,000 years ago. Massilani et al [1] obtained 43 mtDNA control region sequences and 16 complete mitogenomes. Soubrier et al [2] present sequences of 65 control region sequences and 13 complete mitogenomes as well as nuclear DNA sequences for 13 samples, accomplished by capturing 10,000 flanking sequences of SNPs from the Illumina 50K SNP panel.…”