Geographic drivers of diversification in loliginid squids with an emphasis on the western Atlantic species

AimIdentifying the mechanisms driving divergence in marine organisms is challenging as opportunities for allopatric isolation are less conspicuous than in terrestrial ecosystems. Here, we aim to estimate a dated phylogeny of the squid family Loliginidae, and perform ecological niche analyses to explore biogeographic and evolutionary patterns giving rise to extant lineages in this group, with particular focus on cryptic species with population structure along the western Atlantic coast. LocationWorld-wide. TaxonClass Cephalopoda, Family Loliginidae MethodsWe used three loci to infer gene trees and perform species delimitation analysis to detect putative cryptic speciation events. We then estimated a dated species tree under the Bayesian multispecies coalescent and used it to reconstruct ancestral distributions based on the currently known ranges of the species. Also, we tested the hypothesis of niche divergence in three recently diverged species subpopulations of the northwestern and southwestern Atlantic Ocean by ecological niche modeling and niche overlap measurement from occurrence data. ResultsThe phylogenetic analyses confirmed the monophyly for the current twenty-six species of the Loliginidae family. Our ancestral area reconstruction and divergence estimation revealed the origin and geographical dispersal of loliginid lineages. Additionally, the phylogenetic analysis and the species delimitation analysis supported geographic structure within D. pleii, D. pealeii and L. brevis. The ecological niche models revealed unsuitable habitat in the immediately adjacent area of the Amazonian Orinoco Plume, yet suitable habitat characteristics beyond this area. Main conclusionsOur study allowed us to confirm the monophyly of all currently recognized species within the Loliginidae family and we corroborate the biogeographical origin being the Indo-Pacific region in the Cretaceous. We found a possible new cryptic lineage and show evidence of the Amazon-Orinoco Plume as an ecological barrier, which influenced the diversification of this particular group of marine organisms.