Comparative genomics analysis of decapod shrimps in the Pancrustacea clade

• Branchiopods are phylogenetic close to shrimps rather than hexapods.
• Gene family compositions are significantly biased between shrimps and Branchiopods.
• The expanded gene families in shrimps associated with the environment adaptation.
• Nervous system and cellular structure of two shrimps maybe adaptively evolved.

A reference genome is important for genomic and phylogenomic analysis, but except for a brachiopod Daphnia pulex, other crustacean genomes have not been completely sequenced. As one of the most economically important crustaceans, decapod shrimps have attracted great attentions worldwide. But the highly complexity block us from completing shrimp genomes. To explore the decapod shrimp genomes, we performed phylogenomic and comparative genomics analyses of pancrustaceans using transcriptome data. A group of 85 single-copy genes were collected from two shrimps and seven genome-available arthropods for phylogenetic analysis. It was found that the two major members of Pancrustacea, Hexapoda and Crustacea, fall into respective monophyletic clades. D. pulex and shrimps were estimated divergent at about 395 Myr and the gene family compositions were significantly different between them. The gene families involved in ion binding, peroxidase activity and cytoskeletal part were significantly expanded in shrimps, which were considered tightly associated with the seawater environment adaptation. When comparing the two shrimps, gene families involved in synapse in Litopenaeus vannamei and cellular component in Penaeus monodon showed significant expansion, which implies the nervous system of L. vannamei and cellular structure of P. monodon might be adaptively evolved respectively.