Biogeography and Genetic Diversity of Terrestrial Mites in the Ross Sea Region, Antarctica

Abstract

Free-living terrestrial mites (Acari) have persisted through numerous glacial cycles in Antarctica. Very little is known, however, of their genetic diversity and distribution, particularly within the Ross Sea region. To redress this gap, we sampled mites throughout the Ross Sea region, East Antarctica, including Victoria Land and the Queen Maud Mountains (QMM), covering a latitudinal range of 72–85 °S, as well as Lauft Island near Mt. Siple (73 °S) in West Antarctica and Macquarie Island (54oS) in the sub-Antarctic. We assessed genetic diversity using mitochondrial cytochrome c oxidase subunit I gene sequences (COI-5P DNA barcode region), and also morphologically identified voucher specimens. We obtained 130 sequences representing four genera: Nanorchestes (n = 30 sequences), Stereotydeus (n = 46), Coccorhagidia (n = 18) and Eupodes (n = 36). Tree-based analyses (maximum likelihood) revealed 13 genetic clusters, representing as many as 23 putative species indicated by barcode index numbers (BINs) from the Barcode of Life Datasystems (BOLD) database. We found evidence for geographically-isolated cryptic species, e.g., within Stereotydeus belli and S. punctatus, as well as unique genetic groups occurring in sympatry (e.g., Nanorchestes spp. in QMM). Collectively, these data confirm high genetic divergence as a consequence of geographic isolation over evolutionary timescales. From a conservation perspective, additional targeted sampling of understudied areas in the Ross Sea region should be prioritised, as further diversity is likely to be found in these short-range endemic mites.

Editorial: Polar Genomics in a Changing World

“…To link patterns of genetic diversity to longer-term processes, Collins et al [9] surveyed the genetic diversity of four terrestrial mite genera in the Ross Sea region of Antarctica.…”

Terrestrial nematodes from the Maritime Antarctic

“…Further, this has an impact on the potential to assess fauna endemicity, which is critical for examining Antarctic biogeography within a global context ( Andrássy 1998 ). There are numerous cases of misclassification and underestimation of the diversity for most microfaunal groups in Antarctica, likely due to poor taxonomic resolution caused by insufficient sampling and their difficult identification ( Adams et al 2006 , Iakovenko et al 2015 , Carapelli et al 2017 , Short et al 2022 , Collins et al 2023 ), as well as the low degree of the development and application of molecular taxonomy.…”