Limited long-distance dispersal success in a Western European fairy shrimp evidenced by nuclear and mitochondrial lineage structuring

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.

The Strait of Gibraltar is an ineffective palaeogeographic barrier for some flightless darkling beetles (Coleoptera: Tenebrionidae: Pimelia)

The geographic distribution of a species is shaped by its biology and by environmental and palaeogeographic factors that interact at different spatial-temporal scales, which leads to distributions and diversification patterns observed between and within lineages. The darkling beetle genus Pimelia has been diversifying for more than 31.2 Mya showing different colonization patterns after the opening of the Gibraltar Strait 5 Mya. Three of the 14 subgenera of Pimelia have populations on both sides of the Strait. Through extensive sampling and the analysis of three molecular markers, we determine levels of intra- and interspecific genetic variation, identify evolutionary lineages in subgenera, estimate their temporal origin and distribution ranges and discuss the historical basis for the geographic and diversification patterns of Pimelia around the Strait. This single geographical feature acted both as a barrier and as a dispersal route for different Pimelia species. The Strait has represented a strong barrier for the subgenus Magrebmelia since the Middle Miocene. However, the subgenera Amblyptera and Amblypteraca share repetitive signatures of post-Messinian colonization across the Strait, possibly driven by stochastic or ‘catastrophic’ events such as tsunamis. Our demographic analyses support Wallace’s hypothesis on insect dispersal stochasticity. Some taxonomic changes, including the designation of a lectotype for Pimelia maura, are also proposed.

Settling taxonomic and nomenclatural problems in brine shrimps, Artemia (Crustacea: Branchiopoda: Anostraca), by integrating mitogenomics, marker discordances and nomenclature rules

High morphological plasticity in populations of brine shrimp subjected to different environmental conditions, mainly salinity, hindered for centuries the identification of the taxonomic entities encompassed within Artemia. In addition, the mismatch between molecular and morphological evolution rates complicates the characterization of evolutionary lineages, generating taxonomic problems. Here, we propose a phylogenetic hypothesis for Artemia based on two new complete mitogenomes, and determine levels of congruence in the definition of evolutionary units using nuclear and mtDNA data. We used a fossil of Artemia to calibrate the molecular clock and discuss divergence times within the genus. The hypothesis proposed herein suggests a more recent time frame for lineage splitting than previously considered. Phylogeographic analyses were performed using GenBank available mitochondrial and nuclear markers. Evidence of gen e flow, identified through discordances between nuclear and mtDNA markers, was used to reconsider the specific status of some taxa. As a result, we consider Artemia to be represented by five evolutionary units: Southern Cone, Mediterranean-South African, New World, Western Asian, and Eastern Asian Lineages. After an exhaustive bibliographical revision, unavailable names for nomenclatural purposes were discarded. The remaining available names have been assigned to their respective evolutionary lineage. The proper names for the evolutionary units in which brine shrimps are structured remain as follows: Artemia persimilis Piccinelli & Prosdocimi, 1968 for the Southern Cone Lineage, Artemia salina (Linnaeus, 1758) for the Mediterranean-SouthAfrican Lineage, Artemia urmiana Günther, 1899 for the Western Asian Lineage, and Artemia sinica Cai, 1989 for the Eastern Asian Lineage. The name Artemia monica Verrill, 1869 has nomenclatural priority over A. franciscana Kellogg, 1906 for naming the New World Lineage. New synonymies are proposed for A. salina (= C. dybowskii Grochowski, 1896 n. syn., and A. tunisiana Bowen & Sterling, 1978 n. syn.), A. monica (= A. franciscana Kellogg, 1906 n. syn., and A. salina var. pacifica Sars, 1904 n. syn.); A. urmiana (= B. milhausenii Fischer de Waldheim, 1834 n. syn., A. koeppeniana Fischer, 1851 n. syn., A. proxima King, 1855 n. syn., A. s. var. biloba Entz, 1886 n. syn., A. s. var. furcata Entz, 1886 n. syn., A. asiatica Walter, 1887 n. syn., A. parthenogenetica Bowen & Sterling, 1978 n. syn., A. ebinurica Qian & Wang, 1992 n. syn., A. murae Naganawa, 2017 n. syn., and A. frameshifta Naganawa & Mura, 2017 n. syn.). Internal deep nuclear structuring within the A. monica and A. salina clades, might suggest the existence of additional evolutionary units within these taxa.