Approximately 35 million years ago, the ancestors of cobras and similar snakes made their first appearance in Asia. The elapoid snakes, with over 700 species, exhibit a wide range of diversity, encompassing both highly venomous creatures like mambas and sea snakes, as well as numerous nonvenomous species. These snakes can be found in various subtropical and tropical regions worldwide, including rainforests, deserts, and oceans. Despite their widespread presence, the origin story of elapoids has remained somewhat unclear, according to Jeff Weinell, an evolutionary biologist at the American Museum of Natural History in New York City.
Past genetic research on the evolution of elapoids suggested an African origin for the group, with the oldest fossil elapoids dating back 25 million years originating from Africa, including an early African file snake (Gonionotophis). Recent genetic studies, however, have indicated an Asian origin for elapoids, although these studies, along with the Africa-leaning ones, have relied on a limited amount of DNA data.
“The sequences used in those studies did not provide enough information to accurately determine the evolutionary relationships among these snakes,” explains Weinell.
To address this, Weinell and his team collected DNA samples from 65 snake species across 22 families, analyzing and comparing over 3,100 locations in the snakes’ genomes. They also incorporated previously published genetic data from 434 additional snake species. By constructing an elapoid evolutionary tree, the researchers were able to illustrate the relationships between species and the timing of lineage divergence. The more genetic markers shared between two species, the more recent their common ancestor may be.
2024-08-06 18:01:00
Originally published on www.sciencenews.org