![]() ![]() Unfortunately, poor taxonomy is one of the curses of the study of free-living protists, including arcellinid testate amoebae, leading, for instance, to endless debates about the existence of biogeographical patterns in the distribution of free-living protists (Foissner, 2008, Heger et al., 2009, Mitchell and Meisterfeld, 2005), and possibly undermining their use in palaeoecological studies (Payne et al. We focus here on Arcellinid testate amoebae, a group of free-living, mostly heterotrophic protists.Īrcellinid testate amoebae are a good model for studies on the biodiversity, biogeography and evolution of free-living protists because of their ubiquity, diversity, abundance and taxonomically diagnostic test (Alves et al., 2010, Alves et al., 2012, Foissner, 2006, Heger et al., 2011b, Smith et al., 2008). The huge gap in knowledge and research effort that exists between microscopic and macroscopic diversity calls for good model taxa that can be used to address such questions. 2011) and the percentage divergence in given genes required to identify separate species (Kosakyan et al., 2012, Mayr, 1964, Nassonova et al., 2010). ![]() cosmopolitanism debate), (2) the definition of what constitutes a species for micro organisms it is not known if and how far they go through genome recombination (but see Lahr et al. There are several causes for this discrepancy, among which: (1) the recognition or not of local distributions among free-living microbes (i.e. This estimate is in clear conflict with other analyses suggesting much higher diversity and a dominance of microorganisms (Cotterill, 1995, Finlay et al., 2004, Foissner, 1997, Foissner, 1998, Foissner, 1999). A recent analysis suggests that the total species diversity is about 8.7 million species and is dominated by multicellular organisms, mostly animals (Mora et al. Mitchell et Lara.Įstimating global biodiversity has long been a subject of debate and the main uncertainty lies in the diversity of microorganisms, including bacteria, archaea, unicellular protists and micro-metazoa. rotunda (Penard 1890), describe three new species: N. collaris ( Ehrenberg 1848) Kosakyan et Gomaa, change N. We redefine Nebela tincta (Leidy) Kosakyan et Lara and N. We therefore revise the taxonomy of the group. We show here that small variations in test morphology that have been often overlooked by traditional taxonomy correspond to distinct haplotypes. ![]() ![]() Our goals were (1) to clarify the taxonomy and the phylogenetic relationships within this group, and (2) to evaluate if individual genotypes corresponded to specific morphotypes and the extent of phenotypic plasticity. We examined the relationship between morphological and genetic diversity within this species complex by combined analyses of light microscopy imaging and Cytochrome Oxidase Subunit 1(COI) sequences obtained from the same individual amoeba cells. The taxonomic validity of characters used to define species within this group is debated and causes confusion in studies of biogeography, and applications in palaeoecology. Nebela tincta–collaris–bohemica (Arcellinida) is a species complex of small to medium-sized (ca.100 μm) testate amoebae common in peat bogs and forest soils. The seasonal variations in the proportions of prey categories in the ecosystem and the percentage of identifiable prey lead us to hypothesise that (1) Nebela collaris sensu lato ingest mainly immobile, senescent or dead organisms, and (2) that the more mobile micro-organisms such as ciliates and micro-Metazoa become more accessible, in relatively dry conditions, when the water film is thin.Species identification by means of morphology is often problematic in protists. Large ciliates, rotifers and small testate amoebae were also ingested, but mainly in summer. Among the identified prey, those most frequently ingested were micro-algae (45% of the total predator-prey associations, especially diatoms: 33%), and spores and mycelia of fungi (36%). On average, 17.4% of Nebela collaris sensu lato specimens were observed associated with prey, 71% of which could not be identified because of their poor preservation state. The average abundance of Nebela collaris sensu lato was 29582 ind. Population dynamics and food preferences of the testate amoeba species complex Nebela tincta major-bohemica-collaris (“Nebela collaris sensu lato”) were described from a Sphagnum peatland over one growing season. ![]()
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