Is Munida gregaria (Crustacea: Decapoda: Munididae) a truly transpacific species?

The complete mitochondrial genome of squat lobster, Munida gregaria (Anomura, Galatheoidea, Munididae)

We determined the mitogenome sequence of Munida gregaria (Fabricius 1793) (Anomura, Galatheoidea, Munididae), which is the first complete mitogenome sequence in the family Munididae Ahyong et al., 2010. The mitogenome of M. gregaria is 16 326 bp in length and contains 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), two ribosomal RNAs (rRNAs) and two control regions (CRs). Mitogenome analysis of M. gregaria showed an extra copy of the CR and rearrangements of two PCGs (nad2 and nad3) compared to the arthropod ground pattern. Additionally, it contains a tRNA (trnY) inversion and rearrangements of two PCGs (nad1 and nad3) when compared with that of Neopetrolisthes maculatus and Shinkaia crosnieri, respectively. The phylogenetic tree confirmed that M. gregaria belongs to the superfamily Galatheoidea within Anomura. Our results will be useful for the detailed study of mitogenome evolution and the phylogenetic relationships among the superfamily in the infraorder Anomura.

Genetic relationships between Atlantic and Pacific populations of the notothenioid fish Eleginops maclovinus: the footprints of Quaternary glaciations in Patagonia

The genetic relationships between the Pacific and the Atlantic populations of marine coastal biota in Southern South America have been analyzed in few studies, most of them relying on a single mitochondrial locus. We analyzed 10 polymorphic microsatellite loci, isolated from a dinucleotide-enriched Eleginops maclovinus genomic library, in a total of 240 individuals (48 from each of 5 sampled sites: 2 Atlantic, 2 Pacific and 1 in Beagle Channel). The results were contrasted against a previous work on the same species with mitochondrial DNA (mtDNA). Observed heterozygosity within localities ranged from 0.85 to 0.88 with the highest overall number of alleles observed at the northernmost locality on the Pacific side (Concepción), but no clear geographic pattern arose from the data. On the other hand, the number of private alleles was negatively correlated with latitude (Spearman's rs test, P=0.017). Among-population variance was low but significant (1.35%; P<0.0001, analysis of molecular variance (AMOVA)) and low genetic differentiation between populations was observed (pairwise FST values ranged from 0 to 0.021). A Mantel test revealed a significant correlation between geographic distances and FST (r=0.56, P=0.047). This could be partially accounted by the Atlantic versus Pacific population differentiation detected in three different analyses (STRUCTURE, SAMOVA (Spatial Analysis of MOlecular VAriance) and a population phylogeny). The observed pattern is compatible with a history of separation into two glacial refugia that was better captured by the multilocus microsatellite data than by the mtDNA analysis.