Draft genomes of four Triops and Lepidurus tadpole shrimp species (Crustacea, Branchiopoda, Notostraca).

This analysis presents five draft genome assemblies of four Notostraca taxa. The lineage’s origin dates back to the Permian/Upper Devonian and the extant forms show a striking morphological similarity to fossil taxa. The analyses of the five complete genomes sequenced, in comparison with other Branchiopoda genomes available, show that despite the apparent morphological stasis, Notostraca share a dynamic genome evolution with a genomic turnover for gene families expansion/contraction and transposable elements content comparable to other branchiopods. Notostraca seem to be characterized by a lower genome-wide substitution rate in comparison to other clades; nonetheless a subset of genes shows a faster evolutionary pace compared to other branchiopods, highlighting once more the difficulty in making generalization on genomic stasis versus dynamism. Furthermore, we explored the possible effects of different reproductive strategies on genome evolution in Triops: while the parthenogenetic/hermaphroditic lineage showed a relaxation of selective pressures, the analysis of transposable element accumulation suggested a more complex scenario, possibly independent from the breeding system. Besides providing new genomic resources for the study of these organisms, which appear relevant for their ecology and evolution, we also confirmed the decoupling of morphological and molecular evolution.<br>