Cryptic diversity with wide salinity tolerance in the putative euryhalineTestudinella clypeata(Rotifera, Monogononta)

Abstract

Aquatic faunas in fresh, brackish, and salt waters are usually well defined and differ amongst these three habitats. Nonetheless, some animals are known to be euryhaline, namely present across wide salinity ranges. The wide tolerance of putative euryhaline species has, however been refuted in some cases by DNA taxonomy, which has uncovered cryptic diversity with narrow ecological niches. We aim to improve knowledge on the putative euryhalinism of microinvertebrates and test whether it might actually be a real phenomenon or if euryhaline species are mostly a consequence of our previous inability to identify cryptic species with narrow salinity ranges, as discovered in Brachionus plicatilis. Using morphological analyses and DNA taxonomy, we investigated the species reality and distribution of a putative euryhaline rotifer species, Testudinella clypeata, and evaluated whether cryptic species are ecologically and/or geographically segregated. Different DNA taxonomy approaches concurred in revealing the presence of seven cryptic species within the T. clypeata morphospecies, which, in contrast to what has been previously detected, are actually euryhaline. Moreover, differences in analysed morphological traits were not significantly different amongst cryptic species. This suggests that DNA taxonomy improves our estimates of the actual diversity of microscopic species, in contrast to the morphological approach.

High diversity in Keratella cochlearis (Rotifera, Monogononta): morphological and genetic evidence

“…Cryptic species complexes in rotifers are often inferred based on the mitochondrial COI (Suatoni et al, 2006;Obertegger et al, 2012Obertegger et al, , 2014Leasi et al, 2013;Fontaneto, 2014;Malekzadeh-Viayeh et al, 2014). We extracted DNA from single live individuals with 35 ll of Chelex (InstaGeneMatrix, Bio-Rad, Hercules, CA, USA).…”

“…For all methods, the outgroup was excluded prior to the analyses. We took the results of the GMYC approach as our baseline results because previously rotifer diversity was investigated by it for different species (Obertegger et al, , 2014Leasi et al, 2013;Malekzadeh-Viayeh et al, 2014). The GMYC approach is based on branching rates along an ultrametric tree (here from BEAST) to distinguish between species-level (Yule, slower) and populationlevel (coalescent, faster) branching rates.…”

“…It detects the gaps in the distribution of genetic pairwise distances. This method has been successfully used to delimit species of the meiofauna (Tang et al, 2012;Leasi et al, 2013). Here, all aligned K. cochlearis sequences were used for ABGD.…”

“…(García-Morales & Elías-Gutiér-rez, 2013), Polyarthra dolichoptera (Obertegger et al, 2014), Synchaeta spp. , and Testudinella clypeata (Leasi et al, 2013). The occurrence of cryptic species is often related to rotifer ubiquity and their wide tolerance to environmental parameters such as salinity (Ciros-Pérez et al, 2001a), temperature (Gómez & Snell, 1996;Ortells et al, 2003;Papakostas et al, 2012) or total phosphorus .…”

A checklist of the freshwater rotifer fauna of Thailand (Rotifera, Monogononta, Bdelloidea)

“…Fontaneto et al, 2009;García-Morales and Elías-Gutiér-rez, 2013;Leasi et al, 2013). Considering this, we feel that the time has come to re-evaluate available literature records of Thai Rotifera, to serve as a basis for future work utilising the new techniques that are increasingly becoming available.…”