Patterns of Genetic Variation in the Eisenia nordenskioldi Complex (Oligochaeta: Lumbricidae) along an Elevation Gradient in Northern China

Abstract

Eisenia nordenskioldi is the dominant earthworm species in many tundra and boreal habitats. Nothing is known about the genetic diversity of this species along the elevation gradient in China. This study sampled 28 individuals in the E. nordenskioldi complex from Wuling Mountain, northern China, to examine their external morphology and genetic diversity. Mt. Wuling is the southern limit of the distribution of the E. nordenskioldi complex. The specimens from Mt. Wuling were classified into three groups along an elevation gradient. Mismatch distribution analysis suggested that the Pleistocene glaciations possibly did not significantly affect the distribution of earthworm species in this region. We also found that elevation affected the genetic diversity, but not the external morphology of E. nordenskioldi. Given the altitudinal genetic diversity within the E. nordenskioldi complex, the phylogeography of this species provides important information for the zoogeographic reconstruction of the mountains in northern China. With the relatively limited sample size, the result is not conclusive, and further studies need to be conducted in the future to verify the results.