TRINIDAD AND TOBAGO (CARIBBEAN–SOUTH AMERICAN) GEOGENOMICS: RECONCILING AND SYNTHESIZING PUBLISHED GENETICS DATA INTO A COMPREHENSIVE GEOLOGIC, PALEOGEOGRAPHIC, AND GEOMORPHIC MODEL

Geogenomics is an emerging field that links genetics and genetic clocks of key biota to geology, paleogeography, and landscape development. Over the past several decades, detailed genetic studies have been published for many endemic and cosmopolitan extant species (n = # of species) on the Caribbean islands of Trinidad (a continental island) and Tobago (an oceanic island) near mainland South America. These include studies on freshwater guppies (1), frogs (5), snakes (6), toads (1), lizards (1), and mammals (1) in this archipelago. These case studies link in time (genetic clocks) and space (paleogeography) evolutionary and paleogeographic events in the archipelago to those in mainland South America. We synthesize and assemble the Cenozoic-Recent geology including, tectonics, paleoclimate, and landscape development in the archipelago and on the mainland into a comprehensive geological model that highlights key geological events (e.g., rise and fall of the coastal Cordillera, rise of the Andes, inception and deflection of Orinoco River, STEP fault migration, glacial and interglacial sea level change, inception of Gulf of Cariaco and Gulf of Paria pull-apart basins, etc.). We synthesize the key published genetic (e.g., divergence, vicariance, common ancestor, etc.) events into this geological framework for the: Holocene-Pleistocene, Pliocene, and Miocene. Highlights to-date include: 1) A link in Trinidad between Holocene-Pleistocene differential coastal cordillera sinking and rising, headward stream erosion during glacial low stands, and a major discontinuity in freshwater guppy (Poecilia reticulata) genetics. 2) Symmetric sinking of Trinidad and Venezuela’s coastal mountains into the intervening Gulf of Paria pull-apart to isolate (on Cerro Humo, Paria, Venezuela; El Tucuche-Cerro del Aripo, Northern Range, Trinidad) amphibian subpopulations into two separate gene pools. 3) Common snake ancestors that stretch across South America and reach back into the Miocene, followed by Pliocene and glacial (Pleistocene) sea-level low-stands that allowed for migrations to bypass Trinidad and connect Tobago directly to mainland South America; the later explain unexpected fossorial and stream snake (coral snake mimic) spatial distributions and genetics.