Changes in oribatid mite community structure along two altitudinal gradients in Asia and Europe as related to environmental factors

Changes in biodiversity patterns along environmental gradients are receiving increased interest in context of climate change. Altitudinal changes in the diversity of plants and above ground animals are well studied, whereas soil animals received little attention. Here, we analyzed the patterns of diversity, community structure and reproductive mode of soil-living oribatid mites along an altitudinal gradient at two mountain ranges in Eurasia (Changbai Mountain in China and the Alps in Europe) at similar latitudes and their potentially driving factors. We hypothesized that oribatid mite species richness, abundance and the frequency of parthenogenesis decrease with altitude, i.e. with abiotic conditions becoming more adverse. In addition, we hypothesized oribatid mite community composition to change with increasing altitude with the communities at high altitudes becoming more similar between the two mountain ranges. Moreover, we hypothesized that at the community level parthenogenetic reproduction is becoming less important at higher altitudes. Species abundance and richness on Changbai Mountain were generally lower than in the Alps. Abundance as well as species richness in the Alps decreased with altitude, whereas it did not change significantly on Changbai Mountain. Oribatid mite community composition differed between the two mountains, but remained more similar across altitudes on Changbai Mountain than in the Alps. The percentage of parthenogenetic individuals and species was higher on Changbai Mountain than in the Alps, but did not change with altitude at both mountains. Almost all species that overlapped between the two mountains reproduced via parthenogenesis. The observed differences were mainly due to larger temperature fluctuations and more severe frost on Changbai Mountain compared with the Alps. High frequency of parthenogenetic reproduction in species overlapping between the two mountains suggests that parthenogenetic taxa, typically characterized by generalistic genotypes, tend to have broader distribution ranges than sexual taxa.