Recent speciation and hybridization in Icelandic deep-sea isopods: an integrative approach using genomics and proteomics

Abstract

The isopod species Haploniscus bicuspis (G.O. Sars, 1877) shows circum-Icelandic distribution in a wide range of environmental conditions and along well-known geographic barriers, such as the Greenland-Iceland-Faroe (GIF) Ridge. We wanted to explore population genetics, phylogeography and cryptic speciation as well as to investigate whether previously described, but unaccepted subspecies have any merit. Using the same set of specimens, we combined mitochondrial COI sequences, thousands of nuclear loci (ddRAD), and proteomic profiles, plus selected morphological characters using Confocal Laser Scanning Microscopy (CLSM). Five divergent genetic lineages were identified by COI and ddRAD, two south and three north of the GIF Ridge. Assignment of populations to the three northern lineages varied and detailed analyses revealed hybridization and gene flow between them, suggesting a single northern species with a complex phylogeographic history. No apparent hybridization was observed among lineages south of the Ridge, inferring the existence of two more species. Differences in proteomic profiles between the three putative species were minimal, implying an ongoing or recent speciation process. Population differentiation was high, even among closely associated populations, and higher in mitochondrial COI than nuclear ddRAD loci. Gene flow is apparently male-biased, leading to hybrid zones and instances of complete exchange of the local nuclear genome through immigrating males. This study did not confirm the existence of subspecies defined by male characters, which probably characterize different male developmental stages present in all species.

Adding pieces to the puzzle: insights into diversity and distribution patterns of Cumacea (Crustacea: Peracarida) from the deep North Atlantic to the Arctic Ocean

“…Our cumacean examples do support the finding in other peracarid taxa (amphipods and isopods) of either overestimations ( Lörz et al, 2020 ) or underestimations of intraspecific divergence ( Brix, Svavarsson & Leese, 2014b ; Jennings, Golovan & Brix, 2019 ; Paulus et al, in press ). This emphasizes that sampling from a geographically limited portion of a species’ range only risks missing relevant genetic variation, which blurs an important line between species-level and population-level diversity.…”

Peer Review #1 of "Adding pieces to the puzzle: insights into diversity and distribution patterns of Cumacea (Crustacea: Peracarida) from the deep North Atlantic to the Arctic Ocean (v0.1)"

“…Our cumacean examples do support the finding in other peracarid taxa (amphipods and isopods) of either overestimations (Loerz et al, 2020) or underestimations of intraspecific divergence (Brix et al, 2014b;Jennings et al, 2019;Paulus et al, 2021). This emphasizes that sampling from a geographically limited portion of a species' range only risks missing relevant genetic variation, which blurs an important line between species-level and population-level diversity.…”

Proteomic fingerprinting enables quantitative biodiversity assessments of species and ontogenetic stages in Calanus congeners (Copepoda, Crustacea) from the Arctic Ocean

“…However, in metazoan identification it is still in its infancy. Nevertheless, successful species identification of specimens has been achieved from a large variety of taxonomic groups such as different crustaceans (Bode et al, 2017; Hynek et al, 2018; Kaiser et al, 2018; Kürzel et al, 2022; Laakmann et al, 2013; Paulus et al, 2022; Rossel et al, 2019; Rossel & Martínez Arbizu, 2018b, 2019), fish (Maász et al, 2017; Mazzeo et al, 2008; Rossel et al, 2020; Volta et al, 2012), cnidarians (Holst et al, 2019; Korfhage et al, 2022), molluscs (Hamlili, Thiam, et al, 2021; Wilke et al, 2020) and a large variety of insects, preferentially those which are potential disease vectors (Dieme et al, 2014; Hasnaoui et al, 2022; Loaiza et al, 2019; Mathis et al, 2015; Nabet et al, 2021; Nebbak et al, 2017; Yssouf et al, 2014).…”