Mitochondrial DNA (COI) analyses reveal that amphipod diversity is associated with environmental heterogeneity in deep‐sea habitats

Abstract

The relationship between species diversity and environmental parameters is poorly understood for the mobile macrofauna of deep-sea habitats due to under-sampling and subsequent lack of accurate taxonomic information. To redress this, cytochrome oxidase c subunit I (COI) DNA sequences were used to estimate species diversity and to compare phoxocephalid amphipod assemblages among 20 stations encompassing a range of environmental conditions. Two regions, east (Chatham Rise) and west (Challenger Plateau) of New Zealand were sampled to depths of 200-1200 m with an epibenthic sled. Using a comparison among identified morphospecies, we found a clear gap in sequence divergences between 6% and 13% and used a 6% threshold to designate molecular operational taxonomic units (MOTUs), as a surrogate to putative species. DNA sequences (n = 297) revealed high total diversity (n = 49 MOTUs), as well as high beta diversity (28 MOTUs found at single location only). Novel phoxocephalid MOTUs were found at most stations, especially on Challenger Plateau and the flanks of Chatham Rise. Analyses of interstation assemblages revealed a major split between regions, indicating minimal overlap in taxon distributions. A cluster of highly similar stations was identified, broadly distributed over the crest of Chatham Rise, in association with elevated food availability, probably resulting from higher surface productivity and relatively shallow depth. Accordingly, multivariate analysis revealed a strong correlation between phoxocephalid assemblages and food supply. This study highlights the value of molecular approaches, in particular COI sequences, for quantifying and comparing diversity in under-sampled and/or under-studied taxa.

Can Environment Predict Cryptic Diversity? The Case of Niphargus Inhabiting Western Carpathian Groundwater

“…Populations in each hydrographic basin are characterized by monophyly and concordance between nuclear and mitochondrial data. The patristic distance on COI between northern and southern “Laticaudatus” is below the proposed cut-off divergence level for species delineation in crustaceans [54], however it is within the cut-off divergence level proposed for marine amphipods [63]. Whatever the lower boundary cut-off divergence is, genetic and distributional data suggest that the two lineages within the “Laticaudatus” clade have been evolving independently for some time.…”

Population genetic structure and connectivity of deep‐sea stony corals (Order Scleractinia) in the New Zealand region: Implications for the conservation and management of vulnerable marine ecosystems

“…In combination, these findings provide evidence for the hypothesis that currents/fronts associated with the Chatham Rise act as a barrier to gene flow for several species across multiple phyla. Significant genetic differentiation has already been reported at the geomorphic population level in noncoral species between, for example, the Challenger Plateau and the Chatham Rise (Bors et al., ; Knox et al., ). These results, combined with those for the deep‐sea corals, support the hypothesis that oceanic dynamics contribute to the formation of fine‐scale population structure amongst populations on different geomorphic features in the New Zealand region.…”

Starting aDNAbarcode reference library for shallow water polychaetes from the southern European Atlantic coast

“…This reference library can be of paramount importance for biomonitoring of coastal benthic communities using new high‐throughput sequencing technologies (see Costa & Antunes ; Cristescu ), or for the diagnosis of poorly known deep sea species (Knox et al . ). Moreover, the data gathered for species, during the process of building the DNA barcode library, can be used to investigate trophic interactions, namely by identifying the polychaete species in the gut of fish and other predators (see Smith et al .…”