Evidence for a single population expansion event across 24,000 km: the case of the deep‑sea scavenging amphipod Abyssorchomene distinctus

Anthropogenic activities such as mining pose a putative threat to deep-sea ecosystems and baseline studies of key indicator species are required to assess future loss of biodiversity. We examined population genetic structure, connectivity, cryptic diversity and phylogeography of the deep-sea scavenging amphipod, Abyssorchomene distinctus, using DNA sequence data (mitochondrial COI and nuclear 28S genes) from 373 specimens collected from six abyssal basins. We observed a striking absence of cryptic diversity, suggesting a single, widely distributed species in the Pacifc and Indian Ocean. A single event of population expansion across distances up to 24,000 km is further supported by a main ancestral haplotype in the star-like shaped COI haplotype network, a skewed nucleotide mismatch distribution and deviations from evolutionary neutrality tests. In the Pacifc, A. distinctus showed weak genetic population structure and low diferentiation between the basins of the Clarion-Clipperton Zone and the DISCOL Experimental Area, suggesting a possible higher chance of recovery from deep-sea mining impacts. However, since our data indicate a single recent historic population expansion event, A. distinctus populations will likely be afected to unknown extents, as the exact drivers shaping distribution and dispersion of A. distinctus are still unclear

Peer Review, Impact Factor

https://doi.org/10.1007/s10750-023-05447-5