A Multi-gene Analysis Reveals Multiple Highly Divergent Lineages of The Isopod Chelator Insignis (Hansen, 1916) South of Iceland

Abstract

Abstract:The eurybathic isopod species Chelator insignis shows a wide distribution south of Iceland. We analysed 51 specimens from shelf (213-305 m depth), slope (885-891 m and 1380-1390 m depth) and deep−sea habitats (2750 m) south of Iceland with different DNA markers. A fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) was studied for 47 specimens, 16S was studied for 36 specimens, and a fragment for the 18S rRNA gene could be amplified for 11 specimens. For the COI data, specimens clustered into five distinct lineages each separated by ³20% uncorrected pairwise distances. Both the mi− tochondrial 16S and the nuclear 18S sequence data further support this deep divergence, suggesting the presence of overlooked species inside the nominal C. insignis. Populations on the shelf occurring east and west of the Reykjanes Ridge were genetically identical sug− gesting that this ridge is not a barrier to gene flow. However, populations from different depth ranges differed substantially. Our multi−gene analysis suggests that the newly found species likely have more narrow vertical distribution ranges and highlights a possible role of bathymetry in speciation processes.

Have we so far only seen the tip of the iceberg? Exploring species diversity and distribution of the giant amphipod Eurythenes

“…How bathymetric segregation can be maintained for a vertically migrating species remains a question to be further explored. Various other variables than hydrostatic pressure itself, embedded within the 'factor depth' are more likely to play a significant role in promoting population differentiation and eventually speciation, as outlined in Brix, Svavarsson, and Leese (2014). These environmental factors that vary across wide depth ranges include temperature, dissolved oxygen concentration, nutrient flux, topographic complexity and sediment characteristics (reviewed in Gage and Tyler 1991).…”

“…However, these species can accomplish longer distance dispersal via larval propagules, whilst peracarid crustaceans do not have larval stages. Nonetheless, an undersea ridge did not represent a barrier for a small non-dispersive isopod species (Brix, Svavarsson, and Leese 2014). Smaller lysianassoid amphipod species also showed a genetic connectivity between the Southern Ocean, the South and North Atlantic (Havermans 2014).…”

Amphipod family distributions around Iceland

“…The subcluster A2 groups deeper stations from the Iceland and Irminger basins, separated by the Reykjanes Ridge. The lack of a barrier effect has already been observed for other peracarids, including Amphipoda (Svavarsson 1997, Negoescu and Svavarsson 1997, Brix et al 2014b, Jazdzewska et al 2018). In the case of subcluster A2 (see Figure 9), the Iceland Scotland Overflow Water, which is a deep-water, cold current moving from north east into the Iceland Basin and later flowing along the Reykjanes Ridge into the Irminger Basin seems to be responsible for shaping the observed assemblage (Ostmann et al 2014).…”

A new genus for Cirolana troglexuma Botosaneanu & Iliffe, 1997, an anchialine cave dwelling cirolanid isopod (Crustacea, Isopoda, Cirolanidae) from the Bahamas

“…PCR, purification and sequencing methods were applied as described in Brix et al (2014). Purified PCR products were sent for sequencing to GATC Biotech, Germany.…”