Multiloci analyses suggest synonymy among Rhomboplites, Ocyurus and Lutjanus and reveal the phylogenetic position of Lutjanus alexandrei (Lutjanidae: Perciformes)

ABSTRACT Lutjanidae comprises 21 genera and 135 species widespread throughout Atlantic, Indian and Pacific oceans. Nonetheless, the phylogenetic relationships of Lutjaninae remain uncertain. Furthermore, phylogenetic hypotheses for Lutjanus alexandrei, an endemic species from northeastern Brazilian coast, in Lutjanidae are absent so far. Therefore, we carried out multiloci analyses, combining both mitochondrial and nuclear DNA sequences in Lutjaninae species from Western Atlantic focusing on the controversial relationships among Lutjanus, Rhomboplites, and Ocyurus. Besides, we determined the phylogenetic position and dated the origin of L. alexandrei. The phylogenetics trees based on the 4.4 kb for 11 species corroborated the synonym among Lutjanus and the putative monotypic genera. For the dating of L. alexandrei, another nucleotide dataset (3.0 kb; 40 species) validated the genetic identity of this species that diverged from the sister taxon L. apodus between 2.5 - 6.5 Mya, probably as a result of the barrier caused by the muddy outflow from Orinoco and Amazon rivers along the coastal zone. This report is the most robust multiloci analysis to confirm the synonymy of the three genera of Lutjaninae from Western Atlantic and the first reliable inference about the phylogenetic relationships and origin of L. alexandrei.

摘要：笛鲷科（Lutjanidae）包含21个属、135个物种，广泛分布于大西洋、印度洋及太平洋海域。然而，笛鲷亚科（Lutjaninae）的系统发育关系仍未明确。此外，目前尚无关于巴西东北海岸特有物种亚历山大笛鲷（Lutjanus alexandrei）在笛鲷科中的系统发育研究假说。为此，本研究针对西大西洋笛鲷亚科物种开展多位点分子分析，整合线粒体与核DNA序列数据，重点解析笛鲷属（Lutjanus）、菱体属（Rhomboplites）与黄鳍笛鲷属（Ocyurus）之间尚存争议的亲缘关系。同时，本研究还完成了亚历山大笛鲷的系统发育定位，并估算了其起源时间。基于11个物种的4.4 kb序列构建的系统发育树证实，笛鲷属与该假定单型属之间存在同物异名关系。针对亚历山大笛鲷的起源时间估算，另一组涵盖40个物种、长度为3.0 kb的核苷酸数据集验证了该物种的遗传独立性：其与姐妹类群宽条笛鲷（L. apodus）的分化时间介于250万至650万年前，这一分化事件可能由奥里诺科河与亚马逊河沿岸的泥沙径流形成的地理屏障所导致。本研究是目前针对西大西洋笛鲷亚科三属同物异名关系的最稳健多位点分析证据，同时也是首个关于亚历山大笛鲷系统发育关系与起源时间的可靠推断。