Clonal genome evolution and rapid invasive spread of the marbled crayfish

Julian Gutekunst,Ranja Andriantsoa,Jeanne Rasamy,Wolfgang Stein,Cassandra Falckenhayn,Katharina Hanna,Frank Lyko

doi:10.1038/s41559-018-0467-9

Abstract

The marbled crayfish Procambarus virginalis is a unique freshwater crayfish characterized by very recent speciation and parthenogenetic reproduction. Marbled crayfish also represent an emerging invasive species and have formed wild populations in diverse freshwater habitats. However, our understanding of marbled crayfish biology, evolution and invasive spread has been hampered by the lack of freshwater crayfish genome sequences. We have now established a de novo draft assembly of the marbled crayfish genome. We determined the genome size at approximately 3.5 gigabase pairs and identified >21,000 genes. Further analysis confirmed the close relationship to the genome of the slough crayfish, Procambarusfallax, and also established a triploid AA’B genotype with a high level of heterozygosity. Systematic fieldwork and genotyping demonstrated the rapid expansion of marbled crayfish on Madagascar and established the marbled crayfish as a potent invader of freshwater ecosystems. Furthermore, comparative whole-genome sequencing demonstrated the clonality of the population and their genetic identity with the oldest known stock from the German aquarium trade. Our study closes an important gap in the phylogenetic analysis of animal genomes and uncovers the unique evolutionary history of an emerging invasive species.

Highlights

The marbled crayfish Procambarus virginalis is a unique freshwater crayfish characterized by very recent speciation and parthenogenetic reproduction
The only crustacean genomes available are those of the water flea (Daphnia pulex) and the sand flea (Parhyale hawaiensis)[3,4], leaving decapods as a major gap in the phylogenetic analysis of genomes
The propagation of marbled crayfish is facilitated by their parthenogenetic mode of reproduction and their high fecundity[17], which allows the establishment of large populations from single animals[18], and may serve as a model for the spread of invasive species

Summary

Introduction

The marbled crayfish Procambarus virginalis is a unique freshwater crayfish characterized by very recent speciation and parthenogenetic reproduction. Available genome sequences of parthenogenetic animals are currently limited to certain nematodes[19,20,21,22] and the bdelloid rotifer Adineta vaga[23] Their analysis revealed several interesting features that are likely to reflect important strategies for the evolutionary robustness of these parthenogenetic animals, including the presence of allelic regions on the same chromosome in A. vaga[23] and substantial heterozygosity, combined with the loss of key meiosis genes in Diploscapter pachys and Diploscapter coronatus[21,22]. These features were identified in genomes that have been shaped by asexual reproduction for millions of years. We provide a draft genome assembly of the marbled crayfish to investigate the genome structure, evolutionary history, population structure and invasive spread of this unique animal

Methods

Results

Conclusion