Phylogenetic and biogeographic history of the Snooks (Centropomidae: Carangiformes) spanning the closure of the Isthmus of Panama

Aim: Amphiamerican New World fishes provide a unique opportunity to explore the impact of geological processes and the formation of geographic barriers on biological diversification across both spatial and temporal dimensions. We employed phylogenetic and biogeographic methods to assess the impact of the emergence of the isthmus of Panama on the evolutionary history of snooks.

Location: Eastern tropical Pacific and western Atlantic Oceans.

Methods: Bayesian methods were used for phylogenetic inference and divergence time estimation, incorporating the fossil record of Carangidae, Centropomidae, Istiophoriformes, Latidae, and Sphyraenidae to establish a timeline using the methods of stratigraphic intervals for node calibration density specification. Biogeographic models were fitted to test the hypothesis that transisthmian vicariant events are coeval with the Isthmus closure. To estimate ancestral range probability and perform stochastic mapping, we utilized BioGeoBears and the parameters from the best-fitting model. This allowed us to estimate the quantity and kind of biogeographical events.

Results: Our results suggest a sister relationship between Centropomidae and Sphyraenidae with a common ancestor that originated in the Upper Cretaceous (~78.51 Ma). The biogeographic model BAYAreaLIKE + j indicated speciation in sympatry and dispersal (founder effect) as the primary modes of speciation in the genus Centropomus. The dispersion in the family Centropomidae was estimated from the Tropical Eastern Pacific to the tropical western Atlantic since the Oligocene.

Main conclusions: The alignment of divergence times with ancestral species distributions suggests a possible synchrony between the current distribution in Centropomus species and the processes of the formation of the Isthmus of Panama during the Miocene. However, the evidence of only two transisthmic pair suggests that this event was not determinant in allopatric interbasin speciation. Furthermore, recent diversification events within each basin imply an influence of post-closure environmental conditions on the evolution of this group of fishes.

Methods
We collected specimens at local fish markets and landing areas across Caribbean and Pacific localities. All specimens collected were preserved and stored at the fish collection of Universidad del Valle (CIR-UV). Fishes were photographed, and a small fragment of the right pectoral fin was preserved in 96% ethanol and stored at -20 °C.

We extracted DNA following the Salting Out protocol (Sambrook et al. 1989). Four mitochondrial genes (12SrRNA, 16SrRNA, Cytochrome oxidase subunit I - COI, and cytochrome b -CYB) and one nuclear marker, a single-copy locus TMO-4c4 were amplified. The PCR amplification reactions were conducted in a final volume of 15µl containing 1 µl of DNA of stock concentration, 1.5 µl 10X reaction buffer BD (0.8M Tris -HCL, 0.2 M(NH4)2SO4; Solis Bio Dyne), 1.2 µl of 2.0 mM MgCl2, 0.4 mM premixed deoxynucleotide triphosphates, 0.1 µl of 5Uml Taq FIREPOL DNA polymerase (Solis Bio Dyne), and 0.2 µl of each oligonucleotide primer, each at 20mM concentration.