Using DNA taxonomy to investigate the ecological determinants of plankton diversity: explaining the occurrence of Synchaeta spp. (Rotifera, Monogononta) in mountain lakes

Abstract

Summary 1. The occurrence of unresolved complexes of cryptic species may hinder the identification of the main ecological drivers of biodiversity when different cryptic taxa have different ecological requirements. 2. We assessed factors influencing the occurrence of Synchaeta species (monogonont rotifers) in 17 waterbodies of the Trentino‐South Tyrol region in the Eastern Alps. To do so, we compared the results of using unresolved complexes of cryptic species, as is common practice in limnological studies based on morphological taxonomy, and having resolved cryptic complexes, made possible by DNA taxonomy. 3. To identify cryptic species, we used the generalised mixed Yule coalescent (GMYC) model. We investigated the relationship between the environment and the occurrence of Synchaeta spp. by multivariate ordination using two definitions of the units of diversity, namely (i) unresolved species complexes (morphospecies) and (ii) putative cryptic species (GMYC entities). Our expectation was that resolving complexes of cryptic species could provide more information than using morphospecies. 4. As expected, DNA taxonomy provided greater taxonomic resolution than morphological taxonomy. Further, environmental‐based multivariate ordination on cryptic species explained a significantly higher proportion of variance than that based on morphospecies. Occurrence of GMYC entities was related to total phosphorus (TP), whereas no relationship could be found between morphospecies and the environment. Moreover, different cryptic species within the same morphospecies showed different, and even opposite, preferences for TP. In addition, the wide geographical distribution of haplotypes and cryptic species indicated the absence of barriers to dispersal in Synchaeta.

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).…”

Monogonont rotifers as model systems for the study of micro-evolutionary adaptation and its eco-evolutionary implications

“…Another issue that is especially relevant for microevolutionary studies with monogonont rotifers is the existence of cryptic species. Since the discovery of cryptic species in Brachionus plicatilis (Gómez & Serra, 1995;Gómez et al, 2002), the number of rotifer taxa known to be composed of cryptic species has steadily increased during the last decade (Walsh et al, 2009;Obertegger et al, 2012). Furthermore, several studies have provided evidence for substantial ecological segregation among such species (Gabaldón et al, 2015a;Papakostas et al, 2016).…”

Community assembly of rotifers based on morphological traits

“…Keratella, Polyarthra; Stemberger & Gilbert, 1987). The identification of cryptic species with different environmental needs and different competitive abilities as seen for S. pectinata species complex (Obertegger et al, 2012), Brachionus plicatilis species complex (Montero-Pau et al, 2011), and P. dolichoptera complex (Obertegger et al, 2014), respectively, could further elucidate the importance of gross morphologically-based functional traits. In fact, it has recently been shown that different cryptic species of P. dolichoptera show seasonal succession in Lake Tovel (Obertegger et al, 2014).…”