Range sizes of groundwater amphipods (Crustacea) are not smaller than range sizes of surface amphipods: a case study from Iran

Abstract

The connectivity of groundwater aquifers is lower compared to surface waters. Consequently, groundwater species are expected to have smaller distributional ranges than their surface relatives. Molecular taxonomy, however, unveiled that many species comprise complexes of morphologically cryptic species, with geographically restricted distributional ranges in subterranean as well as in surface waters. Hence, the range sizes of surface and groundwater species might be more similar in size than hitherto thought. We tested this hypothesis by comparing the range size of surface amphipods of the genus Gammarus and subterranean amphipods of the genus Niphargus in Iran. We re-analyzed the taxonomic structure of both genera using two unilocus species delimitation methods applied to a fragment of the COI mitochondrial marker, to identify molecular operational taxonomic units (MOTUs), and assessed the maximum linear extent (MLE) of the ranges of MOTUs from both genera. Genus Gammarus comprised 44–58 MOTUs while genus Niphargus comprised 20–22 MOTUs. The MLEs of the two genera were not significantly different, regardless the delimitation method applied. The results remained unchanged also after exclusion of single site MOTUs. We tentatively conclude that in this case there is no evidence to consider that groundwater species are geographically more restricted than surface species.

Demographic history, range size and habitat preferences of the groundwater amphipod Niphargus puteanus (C.L. Koch in Panzer, 1836)

“…However, one cryptic lineage of the Niphargus virei complex in the study of Trontelj et al (2009) had populations separated by 700 km. In another geographical setting, Esmaeili-Rineh et al (2019) revealed almost similar ranges for groundwater and surface amphipods in the mountain ranges of Iran, again averaging less than 200 km Euclidean distances but with maximal linear distance of 644 km for one Niphargus MOTU. Our study suggests that N. puteanus is another such exceptional case.…”

Global distribution of microwhip scorpions (Arachnida: Palpigradi)

“…We estimated species range size for each species as: the maximum linear extents of the range, namely the length of the line connecting the two occurrences farther apart (Esmaeili‐Rineh et al, 2020). We calculated distance according to the haversine method (Sinnott, 1984), which assumes a spherical earth.…”

Determinants of range sizes pinpoint vulnerability of groundwater species to climate change: A case study on subterranean amphipods from the Dinarides

“…The age of the species was estimated using the latest time-calibrated multilocus phylogeny (Borko et al, 2022). The range size was approximated as the maximum linear extent (MLE) to make the study compliant with other studies of the range sizes of groundwater species (Zagmajster et al, 2014;Zagmajster et al, 2018;Esmaeili-Rineh et al, 2020). The…”