Phylogeny of panpulmonate gastropods investigated using a 'reduced-representation' genomic approach

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Analyses using transcriptomic sequence data are revolutionizing deep molluscan phylogeny. Generating whole genomes or expressed sequence tags (ESTs) still is, however, relatively costly and becomes less efficient for shallower phylogenetic levels with rapidly increasing taxon diversity. There is thus a persisting lack of molecular markers available to test novel hypotheses on subgroups. According to our 4-gene analyses, the inner topology and evolution of euthyneuran gastropods, representing roughly 50,000 species, radically differs from traditional concepts. Our recently established taxon Panpulmonata is diverse with regard to species numbers, morphology and biology, comprising a mix of traditional opisthobranch and pulmonate orders, and some enigmatic snail taxa. Mitochondrial gene trees contradicted such a new topology, while EST-based topologies have given local support. Urgent questions remain, i.e. whether or not there is a new euthyneuran tree with monophyletic Panpulmonata, how internal panpulmonate evolution was, and how to resolve the phylogeny of hyperdiverse taxa reliably and efficiently.Newly developed reduced representation genomic approaches using double digest Restriction-Site Associated DNA sequencing (ddRADseq) can generate thousands of independent nuclear genomic sequence markers for hundreds of samples in parallel, i.e. quickly and at very low costs per sample. In the herein proposed project, we want to explore and establish the use of ddRADseqs as phylogenetic markers, from shallow to deeper levels, within the framework of clarifying panpulmonate phylogeny and evolution. We apply for consumables generating more than 1000 ddRADseqs using available DNA from more than 1000 different euthyneurans. This includes an almost complete species sampling of global acochlidians, covers roughly half of the known panpulmonate families with multiple representatives, and considers all relevant major outgroup taxa. Already in the pilot phase of the project applied for herein, i.e. the first 18 months of funding, we hope for robust results, 1) testing the debated monophyly of Panpulmonata and resolving its origin, 2) reconstructing panpulmonate ordinal and family-level phylogeny (excluding most stylommatophorans), 3) resolving the origin and inner evolution of acochlidians, compared to available multi-locus and morphology-based trees. We will apply state of the art phylogenetic and evolutionary analyses, but also perform up-to-date molecular species delimitation approaches. With our massif genomic data (> 300,000 bp per sample) across many subtaxa we will evaluate current paradigms on character evolution and macro-evolutionary patterns among panpulmonates, such as the invasions of terrestrial and limnic systems.