A biogeographic framework of octopod species diversification: the role of the Isthmus of Panama

• Published in: PeerJ (San Francisco, CA) Vol. 8; p. e8691
• Main Authors: Lima, Francoise D, Strugnell, Jan M, Leite, Tatiana S, Lima, Sergio M Q
• Format: Journal Article
• Language: English
• Published: United States PeerJ. Ltd 27.03.2020; PeerJ, Inc; PeerJ Inc
• Subjects: Analysis; Bayesian analysis; Biogeography; Calibration; Conservation Biology; Cytochrome oxidase; Dispersal; Divergence; Fossil calibration; Genes; Genetics; Hypotheses; Land bridges; Marine Biology; Mitochondria; Molecular Biology; Oceans; Octopus; Oxidases; Phylogenetics; Phylogeny; Rhodopsin; rRNA 16S; Sibling species; Speciation; Vicariance; Zoology; Central America; Panama; South America; Isthmus of Panama; Dispersal; Evolution; Fossil calibration; Phylogeny; Vicariance; Octopus; Speciation
• DOI: 10.7717/peerj.8691
• ISSN: 2167-8359

The uplift of the Isthmus of Panama (IP) created a land bridge between Central and South America and caused the separation of the Western Atlantic and Eastern Pacific oceans, resulting in profound changes in the environmental and oceanographic conditions. To evaluate how these changes have influenced speciation processes in octopods, fragments of two mitochondrial (Cytochrome oxidase subunit I, COI and 16S rDNA) and two nuclear (Rhodopsin and Elongation Factor-1α, EF-1α) genes were amplified from samples from the Atlantic and Pacific oceans. One biogeographical and four fossil calibration priors were used within a relaxed Bayesian phylogenetic analysis framework to estimate divergence times among cladogenic events. Reconstruction of the ancestral states in phylogenies was used to infer historical biogeography of the lineages and species dispersal routes. The results revealed three well-supported clades of transisthmian octopus sister species pair/complex (TSSP/TSSC) and two additional clades showing a low probability of species diversification, having been influenced by the IP. Divergence times estimated in the present study revealed that octopod TSSP/TSSC from the Atlantic and Pacific diverged between the Middle Miocene and Early Pliocene (mean range = 5-18 Ma). Given that oceanographic changes caused by the uplift of the IP were so strong as to affect the global climate, we suggest that octopod TSSP/TSSC diverged because of these physical and environmental barriers, even before the complete uplift of the IP 3 Ma, proposed by the Late Pliocene model. The results obtained in this phylogenetic reconstruction also indicate that the octopus species pairs in each ocean share a recent common ancestor from the Pacific Ocean.