Sales João Bráullio de L, Rodrigues-Filho Luis F da S, Ferreira Yrlene do S, Carneiro Jeferson, Asp Nils E, Shaw Paul W, Haimovici Manuel, Markaida Unai, Ready Jonathan, Schneider Horacio, Sampaio Iracilda
Universidade Federal do Pará, Campus Universitário do Marajó-Breves, Faculdade de Ciencias Naturais, Breves, PA CEP 68800-000, Brazil; Laboratório de Filogenômica e Bioinformatica, UFPA-IECOS, Campus de Bragança, Bragança, PA 68600-000, Brazil.
Universidade Federal Rural da Amazônia, Campus Universitário de Capanema, Faculdade de Ciencias Biológicas, Capanema, PA CEP 68600-030, Brazil.
Mol Phylogenet Evol. 2017 Jan;106:44-54. doi: 10.1016/j.ympev.2016.09.014. Epub 2016 Sep 15.
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.
尽管近年来基因分析不断增加，发现了新的头足类物种和系统地理学模式，但南美洲的枪乌贼仍是研究最少的类群之一。有观点认为，在从美国哈特拉斯角（北纬36°）到阿根廷北部（南纬35°）的西大西洋沿岸广泛分布范围内，杜氏枪乌贼（Doryteuthis plei）可能代表不同的谱系，这与该范围内许多环境变量的显著变化一致，包括温度和盐度。在本研究中，从西大西洋沿岸的大量地点采集了杜氏枪乌贼样本，以便在系统地理学背景下研究这些可能物种的分布。使用线粒体细胞色素氧化酶I基因和核视紫红质基因进行了系统地理学分析。利用贝叶斯严格分子钟定年法估计分歧时间，校准依据包括与幽灵蛸（Vampyroteuthis infernalis，1.62亿年前）谱系分歧的化石记录、北美枪乌贼可能的起源（4500万年前）、欧洲枪乌贼（2000万年前）以及太平洋褶柔鱼（Doryteuthis opalescens）的化石耳石（300万年前）。我们的结果表明杜氏枪乌贼内部存在深度遗传分歧。目前描述的物种由两个遗传上不同的分支组成（两两之间的遗传分歧在7.7%至9.1%之间）。一个分支由在大西洋西北部和加勒比海中部大西洋水域采集的个体组成，另一个分支由来自西南大西洋水域的个体组成。分歧时间和采样地点表明物种形成过程大约在1600万年前，这与加勒比板块的中新世中期造山运动完全一致，最终形成了小安的列斯群岛和相邻的俯冲带，同时全球海平面特别低，导致该地区实际上没有大陆架，因此对杜氏枪乌贼来说是一个有效的地理屏障。此外，本研究还提供了墨西哥湾以前未记录的亚种群结构的证据。
