Divergence of cryptic species of Doryteuthis plei Blainville, 1823 (Loliginidae, Cephalopoda) in the Western Atlantic Ocean is associated with the formation of the Caribbean Sea

Abstract

Although recent years have seen an increase in genetic analyses that identify new species of cephalopods and phylogeographic patterns, the loliginid squid of South America remain one of the least studied groups. The suggestion that Doryteuthis plei may represent distinct lineages within its extensive distribution along the western Atlantic coasts from Cape Hatteras, USA (36°N) to northern Argentina (35°S) is consistent with significant variation in a number of environmental variables along this range including in both temperature and salinity. In the present study D. plei samples were obtained from a large number of localities along the western Atlantic coasts to investigate the distribution of these possible species in a phylogeographic context. Phylogeographic analyses were performed using the mitochondrial Cytochrome Oxidase I gene and nuclear Rhodopsin gene. Divergence times were estimated using Bayesian strict clock dating with calibrations based on fossil records for divergence from the lineage containing Vampyroteuthis infernalis (162mya), the probable origins of the North American loliginids (45mya), and the European loliginids (20mya) and fossil statolith from Doryteuthis opalescens (3mya). Our results suggest a deep genetic divergence within Doryteuthis plei. The currently described specie consists of two genetically distinct clades (pair-wise genetic divergence of between 7.7 and 9.1%). One clade composed of individuals collected in northwestern Atlantic and Central Caribbean Atlantic waters and the other from southwestern Atlantic waters. The divergence time and sampling locations suggest the speciation process at approximately 16Mya, which is in full agreement with the middle Miocene orogeny of the Caribbean plate, ending up with the formation of the Lesser Antilles and the adjacent subduction zone, coinciding with a particularly low global sea level, resulting in the practical absence of continental shelves at the area, and therefore an effective geographic barrier for D. plei. Furthermore, this study also provides evidence of previously undocumented sub-population structuring in the Gulf of Mexico.

Biology, distribution and geographic variation of loliginid squids (Mollusca: Cephalopoda) off southwestern Atlantic

“…In addition, these latitudinal movements may promote strong gene flow among different stocks at the SBB. This hypothetical scenario is consistent with a recent genetic analysis that failed to find any relevant genotypic differences between squid from this area and their counterparts on the rest of the South American Atlantic coast (Sales et al 2017).…”

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

“…However, it has been showed (J. B. de L. Sales et al, 2017) that the divergence time of the two clades within D. pleii, one comprising northwestern and central Caribbean Atlantic and the other southwestern Atlantic specimens, was not recent and instead about 16 million years ago. These results contradict our divergence time estimation, the latter suggesting a split between D. plei and D. pealeii no older than 5 mya.…”

“…Many studies have dealt with systematics and macroevolution in lineages of these organisms in the last decade (Kolis & Lieberman, 2019;Lindgren et al, 2012;Strugnell et al, 2006;Strugnell & Nishiguchi, 2007;Tanner, 2018;Wani, 2011). However, very few studies have addressed diversification dynamics from a geographic perspective, covering temporal and phylogenetic hypotheses (but see (Amor et al, 2014;Brakoniecki, 1987;J. B. de L. Sales et al, 2017;Ulloa et al, 2017).…”

“…The increase of available molecular data for the species in the squid family Loliginidae, Lesueur, 1821, has resulted in systematic revisions with more phylogenetic accuracy. Evidence of possible cryptic species has been shown for many genera of loliginid squids (Anderson, 2000;J. B. de L. Sales et al, 2017), including three cases of potential cryptic speciation between lineages in the North and South Atlantic of the species Doryteuthis pealeii, D. pleii and Lolliguncula brevis (de Luna Sales et al, 2013;J.…”

“…B. L. Sales et al, 2014). Also, a couple of studies have been published with divergence time estimates for major cephalopod lineages (Anderson, 2000;J. B. de L. Sales et al, 2017;Ulloa et al, 2017).…”