Aim Most species of temperate regions are believed to have shifted to lower
latitudes or elevations during the glacial periods of the Quaternary. In this study
we test whether this phylogeographic assumption is also true for the plateau
zokor (Eospalax baileyi), a fossorial rodent endemic to the climate-sensitive
Qinghai–Tibetan Plateau (QTP), which ranges in elevation from 2600 to 4600 m.
Location The QTP of western China.
Methods Phylogeographic analyses were conducted based on the mitochondrial
cytochrome b gene sequences of 193 individuals from 20 populations over the
entire range of the species.
Results A total of 54 haplotypes identified in the present study clustered into
four geographically correlated clades located in the interior of the QTP (clade A)
and at the plateau edge (B, C and D). Molecular calibrations suggest that the
interior plateau (A) and plateau-edge (B–D) clades diverged at 1.2 Ma and that
the three plateau-edge clades diverged between 0.85 and 0.80 Ma. These estimates
are concordant with diastrophism and glaciation events in the QTP. Coalescent
tests rejected both the hypothesis that all current populations originated from a
single refugium at a low elevation during the Last Glacial Maximum (LGM) and
the hypothesis that the two lineages diverged during the LGM. The tests instead
supported the hypothesis that there were four refugia during the LGM, and that
the four clades diverged prior to the late Pleistocene.
Main conclusions Our results suggest that Quaternary diastrophisms and
glaciations repeatedly promoted allopatric divergence of the plateau zokor into
geographical clades, and that these regional clades subsequently persisted at high
elevations, rather than migrating to the low-elevation plateau edge during
subsequent glacial ages.
Keywords
Cytochrome b, Eospalax baileyi, genetic divergence, phylogeography, plateau
zokor, rodents, Qinghai–Tibetan Plateau, western China.
The research has been published on Journal of Biogeography (J. Biogeogr.) (2010) 37, 657–668
Li-Zhou Tang1,2,3, Liu-Yang Wang1,3, Zhen-Yuan Cai1, Tong-Zuo Zhang1,
Hai-Xin Ci1,3, Gong-Hua Lin1,3, Jian-Ping Su1* and Jian-Quan Liu4*