Copepoda is one of the most ecologically important animal groups on Earth, yet very few genetic resources are available for this Subclass. Here, we present the first whole genome sequence (WGS, acc. UYDY01) and the first mRNA transcriptome assembly (TSA, Acc. GHAJ01) for the tropical cyclopoid copepod species Apocyclops royi Until now, only the 18S small subunit of ribosomal RNA gene and the COI gene has been available from A. royi, and WGS resources was only available from one other cyclopoid copepod species. Overall, the provided resources are the 8th copepod species to have WGS resources available and the 19th copepod species with TSA information available. We analyze the length and GC content of the provided WGS scaffolds as well as the coverage and gene content of both the WGS and the TSA assembly. Finally, we place the resources within the copepod order Cyclopoida as a member of the Apocyclops genus. We estimate the total genome size of A. royi to 450 Mb, with 181 Mb assembled nonrepetitive sequence, 76 Mb assembled repeats and 193 Mb unassembled sequence. The TSA assembly consists of 29,737 genes and an additional 45,756 isoforms. In the WGS and TSA assemblies, >80% and >95% of core genes can be found, though many in fragmented versions. The provided resources will allow researchers to conduct physiological experiments on A. royi, and also increase the possibilities for copepod gene set analysis, as it adds substantially to the copepod datasets available.
Members of the crustacean subclass Copepoda are likely the most abundant metazoans worldwide. Pelagic marine species are critical in converting planktonic microalgae to animal biomass, supporting oceanic food webs. Despite their abundance and ecological importance, only six copepod genomes are publicly available, owing to a number of factors including large genome size, repetitiveness, GC-content, and small animal size. Here, we report the seventh representative copepod genome and the first genome and the first transcriptome from the calanoid copepod species Acartia tonsa Dana, which is among the most numerous mesozooplankton in boreal coastal and estuarine waters. The ecology, physiology, and behavior of A. tonsa have been studied extensively. The genetic resources contributed in this work will allow researchers to link experimental results to molecular mechanisms. From PCR-free whole genome sequence and mRNA Illumina data, we assemble the largest copepod genome to date. We estimate that A. tonsa has a total genome size of 2.5 Gb including repetitive elements we could not resolve. The nonrepetitive fraction of the genome assembly is estimated to be 566 Mb. Our DNA sequencing-based analyses suggest there is a 14-fold difference in genome size between the six members of Copepoda with available genomic information. This finding complements nucleus staining genome size estimations, where 100-fold difference has been reported within 70 species. We briefly analyze the repeat structure in the existing copepod whole genome sequence data sets. The information presented here confirms the evolution of genome size in Copepoda and expands the scope for evolutionary inferences in Copepoda by providing several levels of genetic information from a key planktonic crustacean species.