Lack of phylogeography in European mammals before the last glaciation

Abstract

In many extant animal and plant species in Europe and North America a correlation exists between the geographical location of individuals and the genetic relatedness of the mitochondrial (mt) DNA sequences that they carry. Here, we analyze mtDNA sequences from cave bears, brown bears, cave hyenas, and Neandertals in Europe before the last glacial maximum and fail to detect any phylogeographic patterns similar to those observed in extant species. We suggest that at the beginning of the last glacial maximum, little phylogeographic patterns existed in European mammals over most of their geographical ranges and that current phylogeographic patterns are transient relics of the last glaciation. Cycles of retreat of species in refugia during glacial periods followed by incomplete dispersal from one refugium into other refugia during interglacial periods is likely to be responsible for the deep genetic divergences between phylogeographic clusters of mtDNA seen today.ancient DNA ͉ glacial refugia ͉ mitochondrial DNA ͉ Pleistocene ͉ population structure

Surprising migration and population size dynamics in ancient Iberian brown bears ( Ursus arctos )

“…Furthermore, AMOVAs suggest little geographic substructure among Spanish and Eu- ropean Pleistocene populations. These new data confirm the lack of phylogeographic discontinuity in European brown bears before the LGM (23). Although Spanish and European Holocene populations appear geographically differentiated in our AMOVAs, a recent study has suggested that gene flow could have continued from the Pleistocene to the Holocene (20).…”

“…Interestingly, we found significant levels of geographic substructure in the current and the Holocene populations (long dataset: F STcurrent ϭ 0.5169, P Ͻ 10 Ϫ5 ; F STHolocene ϭ 0.3391, P Ͻ 10 Ϫ4 ; short dataset: F STcurrent ϭ 0.4540, P Ͻ 10 Ϫ5 ; F STHolocene ϭ 0.3345, P Ͻ 10 Ϫ5 ), but not in the Pleistocene (large dataset: F STPleistocene ϭ 0.17691, P ϭ 0.1723; short dataset: F STPleistocene ϭ 0.1505, P ϭ 0.1885). The results tentatively suggest that gene flow between Europe and Spain was greater during the Pleistocene period than for more recent periods (both at present times and at the Holocene) (23). These observations should be taken as preliminary, however, because (i) the number of haplotypes available for the ancient periods is limited and (ii) the Iberian population clearly depart from the constant size assumption, which is a prerequisite for accurate Fst calculations (see below).…”

“…Using the DNA sequences from 24 modern and 13 ancient Iberian brown bears, in combination with published sequences from seven ancient and one modern Iberian bears (see SI Fig. 3), we have been able to estimate the extent of genetic diversity change in the peninsula through time, from the Pleistocene until today. To test whether the changes in diversity show parallel developments in the rest of Europe, we conducted similar analyses for the non-Iberian European population samples, taking advantage of previously reported haplotypes (4,(18)(19)(20)23). It is noteworthy that the genetic diversity of the Spanish brown bear population continuously decreases from the Pleistocene to modern times (Table 1).…”

“…To include all of the data generated in the present study, we created two datasets, spanning 177 bp and 115 bp of the mitochondrial control region (referred below as the long and short datasets, respectively). In our analyses, we also included European brown bear haplotypes available from GenBank (4,(18)(19)(20)23). Together, the long and short datasets comprise 67 and 71 brown bear sequences, respectively (see SI Datasets 2 and 3).…”

Looking backwards to look forwards: conservation genetics in a changing world

“…However there are exceptions. For example, a recent study investigated the phylogeography of species in Europe before the recent glacial maximum (Hofreiter et al 2004). They sequenced ancient DNA from now extinct species (cave bear and cave hyenas; Crocuta crocuta spelaea) for samples ranging in age from 22000 to 72000 years old.…”