Crocodile evolution rebooted by Ice Age glaciations
16-FEB-2021
Researchers discover impacts of Ice Age sea level changes in the genomes of Caribbean and Pacific crocodiles in Panama
MCGILL UNIVERSITY
Crocodile from a population living on the coast of Panama.
CREDIT
José Avila-Cervantes
Crocodiles are resilient animals from a lineage that has survived for over 200 million years. Skilled swimmers, crocodiles can travel long distances and live in freshwater to marine environments. But they can't roam far overland. American crocodiles (Crocodylus acutus) are found in the Caribbean and Pacific coasts of the Neotropics but they arrived in the Pacific before Panama existed, according to researchers from McGill University.
Over 3 million years ago, the formation of the Isthmus of Panama altered global ocean circulation, connecting North and South America and establishing the Caribbean Sea. This resulted in widespread mixing of species on the continent and separation in the seas. On land, mammals from North America such as mammoths, sabre-toothed cats, horses, and camels invaded South America, and strange mammals like giant ground sloths, armadillos, and opossums from South America invaded North America. This event is known as the Great American Interchange, and the opposite happened in the seas, where new species of corals, clams, and fishes evolved in the separated Pacific and Caribbean waters.
The question a group of McGill and Panamanian researchers asked was: how distant are the Pacific and Caribbean populations from each other and does it match the geological record? Researchers have long suspected that American crocodiles living on the Pacific coast should have diverged genetically enough from Caribbean populations to become unique species.
"We assumed we would detect significant genetic differences between Pacific and Caribbean crocodile populations that were isolated for the past 3 million years," thought José Avila-Cervantes, a recent PhD graduate of McGill University under the supervision of Professor Hans Larsson.
More:
https://www.eurekalert.org/pub_releases/2021-02/mu-cer021621.php
= new reply since forum marked as read
