Three new species of the fairy shrimp Eubranchipus Verill, 1870 (Branchiopoda: Anostraca) from northern Japan and far Eastern Russia

Integrating mitochondrial and nuclear genomic data to decipher the evolutionary history of Eubranchipus species in Japan

Understanding the genetic diversity and evolutionary history of species is crucial for their conservation and management. In this study, we investigated the genetic diversity and phylogenetic relationships among Eubranchipus species occurring in Japan. Phylogenetic analyses revealed that nuclear and mitochondrial data yield incompatible results. In E. uchidai, nuclear data support the monophyly of the Shimokita area, while mitochondrial data indicate a clustering of Higashidori2 individuals with Hokkaido (Ishikari and Wakkanai) E. uchidai. Similar incongruences were observed in E. hatanakai, where nuclear data favor the monophyly of the Chokai area, while mitochondrial data cluster some Chokai pool 3 individuals with Aizu individuals. These incompatibilities might be caused by mitochondrial gene flow. The findings emphasize the importance of considering both nuclear and mitochondrial data during phylogenetic studies and provide valuable insights into the complex dynamics of migration and genetic exchange in Eubranchipus species.

Complete mitochondrial genomes of three fairy shrimps from snowmelt pools in Japan

Background

Fairy shrimps belong to order Anostraca, class Branchiopoda, subphylum Crustacea, and phylum Arthropoda. Three fairy shrimp species (Eubranchipus uchidai, E. asanumai, and E. hatanakai) that inhabit snowmelt pools are currently known in Japan. Whole mitochondrial genomes are useful genetic information for conducting phylogenetic analyses. Mitochondrial genome sequences for Branchiopoda members are gradually being collated.

Results

Six whole mitochondrial genomes from the three Eubranchipus species are presented here. Eubranchipus species share the anostracan pattern of gene arrangement in their mitochondrial genomes. The mitochondrial genomes of the Eubranchipus species have a higher GC content than those of other anostracans. Accelerated substitution rates in the lineage of Eubranchipus species were observed.

Conclusion

This study is the first to obtain whole mitochondrial genomes for Far Eastern Eubranchipus species. We show that the nucleotide sequences of cytochrome oxidase subunit I and the 16S ribosomal RNA of E. asanumai presented in a previous study were nuclear mitochondrial DNA segments. Higher GC contents and accelerated substitution rates are specific characteristics of the mitochondrial genomes of Far Eastern Eubranchipus. The results will be useful for further investigations of the evolution of Anostraca as well as Branchiopoda.

A Review of Recently Discovered Remains of the Pleistocene Branchiopods (Anostraca, Notostraca) from NE Siberia and Arctic Canada

In this study, we examine, identify, and discuss fossil remains of large branchiopod crustaceans collected from six sites across the Beringian region (north-eastern Asia and north-western North America). Eggs and mandibles from Anostraca and Notostraca, as well as a notostracan telson fragment and a possible notostracan second maxilla, were collected from both paleosediment samples and also from large mammal hair. The remains of large branchiopods and other species that are limited to seasonally astatic aquatic habitats (temporary wetlands) could be useful indicator organisms of paleoecological conditions. Different recent large branchiopod species have very different ecological preferences, with each species limited to specific geochemical component tolerance ranges regarding various salinity, cation, and gypsum concentrations. Our purpose is to bring the potential usefulness of these common fossil organisms to the attention of paleoecologists.