Coexisting cryptic species of the Litoditis marina complex (Nematoda) show differential resource use and have distinct microbiomes with high intraspecific variability

Abstract

Differences in resource use or in tolerances to abiotic conditions are often invoked as potential mechanisms underlying the sympatric distribution of cryptic species. Additionally, the microbiome can provide physiological adaptations of the host to environmental conditions. We determined the intra- and interspecific variability of the microbiomes of three cryptic nematode species of the Litoditis marina species complex that co-occur, but show differences in abiotic tolerances. Roche 454 pyrosequencing of the microbial 16S rRNA gene revealed distinct bacterial communities characterized by a substantial diversity (85-513 OTUs) and many rare OTUs. The core microbiome of each species contained only very few OTUs (2-6), and four OTUs were identified as potentially generating tolerance to abiotic conditions. A controlled experiment in which nematodes from two cryptic species (Pm1 and Pm3) were fed with either an E. coli suspension or a bacterial mix was performed, and the 16S rRNA gene was sequenced using the MiSeq technology. OTU richness was 10-fold higher compared to the 454 data set and ranged between 1118 and 7864. This experiment confirmed the existence of species-specific microbiomes, a core microbiome with few OTUs, and high interindividual variability. The offered food source affected the bacterial community and illustrated different feeding behaviour between the cryptic species, with Pm3 exhibiting a higher degree of selective feeding than Pm1. Morphologically similar species belonging to the same feeding guild (bacterivores) can thus have substantial differences in their associated microbiomes and feeding strategy, which in turn may have important ramifications for biodiversity-ecosystem functioning relationships.

Revealing higher than expected meiofaunal diversity in Antarctic sediments: a metabarcoding approach

“…In this study, for each of the main meiobenthic phyla (nematodes, arthropods, platyhelminthes and annelids) (Supplemental Material S1) there were some well-supported clades, particularly in the nematodes and nematodes, where OTUs assigned to the same genus, could potentially comprise species complexes. However without further molecular and taxonomic analysis, these would be difficult to define, but would be highly likely 40 .…”

Identification of sympatric cryptic species of Aedes albopictus subgroup in Vietnam: new perspectives in phylosymbiosis of insect vector

“…Most of these similar bacterial taxa are also found in the water and plants with which mosquitoes are in contact during immature and adult stages [38, 39]. A recent study on the Litoditis marina complex (Nematoda) described a divergent structure between the bacterial microbiota among three cryptic species [40]. The authors suggested a link between the microbiota, intrinsic physiological properties and trophic interactions specificities for each species.…”

Galling problems – the Fergusobia nematode/Fergusonina fly mutualism on myrtaceous hosts

“…Comparison with the aphelenchoidid nematodes associated with fig sycones (Kanzaki et al, 2014;Davies et al, 2015) is relevant here, where four genetically diverse groups of nematodes independently invaded sycones but have apparently converged morphologically due to the common selection pressures operating on them within the fruits (Kanzaki et al, 2014). Cryptic species of the marine bacterivore nematodes Litoditis marina have differences in their respective associated microbiomes, different feeding strategies and high inter-individual variability (Derycke et al, 2016).…”