Positive selection in development and growth rate regulation genes involved in species divergence of the genus Radix

Abstract

BackgroundLife history traits like developmental time, age and size at maturity are directly related to fitness in all organisms and play a major role in adaptive evolution and speciation processes. Comparative genomic or transcriptomic approaches to identify positively selected genes involved in species divergence can help to generate hypotheses on the driving forces behind speciation. Here we use a bottom-up approach to investigate this hypothesis by comparative analysis of orthologous transcripts of four closely related European Radix species.ResultsSnails of the genus Radix occupy species specific distribution ranges with distinct climatic niches, indicating a potential for natural selection driven speciation based on ecological niche differentiation. We then inferred phylogenetic relationships among the four Radix species based on whole mt-genomes plus 23 nuclear loci. Three different tests to infer selection and changes in amino acid properties yielded a total of 134 genes with signatures of positive selection. The majority of these genes belonged to the functional gene ontology categories “reproduction” and “genitalia” with an overrepresentation of the functions “development” and “growth rate”.ConclusionsWe show here that Radix species divergence may be primarily enforced by selection on life history traits such as (larval-) development and growth rate. We thus hypothesise that life history differences may confer advantages under the according climate regimes, e.g., species occupying warmer and dryer habitats might have a fitness advantage with fast developing susceptible life stages, which are more tolerant to habitat desiccation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0434-x) contains supplementary material, which is available to authorized users.

Species Richness, Molecular Taxonomy and Biogeography of the Radicine Pond Snails (Gastropoda: Lymnaeidae) in the Old World

“…However, the most popular molecular classification schemes of the radicine lymnaeids of the Old World were based on impersonal categories such as MOTUs 20 and clades 21 , 34 , without links to the Latin binomial names demanded by the internationally adopted rules of zoological nomenclature. In the absence of an available phylogeny-based taxonomy, both the approaches were widely applying until recently 36 , 43 , 44 . To avoid the problems outlined above, we developed the first DNA barcode reference library of the Old World Amphipepleinae (Supplementary Dataset 1 ).…”

An Annotated Draft Genome for Radix auricularia (Gastropoda, Mollusca)

“…To further increase the contiguity of the draft genome, we applied a third scaffolding step, making use of the cDNA sequence data. Transcriptome contig sequences of R. auricularia and three closely related species (supplementary note 10, Supplementary Material online) were mapped sequentially according to phylogeny (Feldmeyer et al. 2015) using BLAT 35 (Kent 2002), with -extendThroughN enabled apart from default settings, onto the scaffolds; the gapped alignments were then used for joining of sequences with L_RNA_scaffolder (Xue et al.…”

“…Despite this broad range of interests, genomic resources, are scarce and limited to transcriptomes (Feldmeyer et al. 2011, 2015; Tills et al. 2015) and mitochondrial genomes (Feldmeyer et al.…”

Complete mitochondrial and rDNA complex sequences of important vector species of Biomphalaria, obligatory hosts of the human-infecting blood fluke, Schistosoma mansoni

“…There are five families proposed for the gastropod Order Hygrophila: Acroloxidae, Chilinoidae, Planorbidae, Lymnaeidae and Physidae 33 . So far complete mitogenomes are documented only for representatives of the Planorbidae 23 , 24 , Lymnaeidae 34 , and Physidae 35 . The order of mitochondrial genes in the Planorbidae to which Biomphalaria belongs is similar to the Lymnaeidae except for differences in location of a few tRNAs 23 , 34 , whereas gene order is quite different in the Physidae 35 (for more information about the comparative mitogenome gene orders of the gastropod, please see articles) 35 , 36 .…”