Snakes lived an ecological ‘boom’ 66 million years ago
66 million years ago, the extinction 75% of species, including all non-avian dinosaurs, ushered in an era (the Cenozoic) in which mostly mammals and birds found endless empty ecological niches to survive. However, there were other survivors who also made it through to this day.
Snakes evolved to specialize in earthworms, fish, frogs, slugs, snake-shaped eels, even other snakes
A new study, published in the journal PLoS Biology, reveals that snakesThe most elusive and rare in the fossil record on such a broad phylogenetic scale, they also diversified rapidly after mass extinction, to the point of reaching nearly 4,000 species today.
These reptiles “They exploited in all aspects of their diversity,” he tells SINC Michael C. Grundler, first author of the work and researcher in the department of Ecology and Evolutionary Biology of the University of California in Los Angeles. “They evolved to specialize in earthworms, fish, frogs, slugs, snake-shaped eels, even other snakes,” Grundler continues.
As part of that process, these animals developed a whole series of behaviors and morphologies. “Venom and constriction, which allow snakes to subdue prey much larger than themselves, are two important examples,” emphasizes the biologist.
In search of new ecological opportunities
The scientist, along with Daniel L. Rabosky, a co-author from the University of Michigan, focused on the diet of these reptiles to understand their evolution. Both collated published data on the feeding of 882 species of live snakes. Thanks to the use of sophisticated mathematical models, they were able to reconstruct this food diversification.
Sometimes those opportunities are generated by extinctions, like the one that wiped out the dinosaurs. Others are caused by the dispersal of an ancestor to another land
The results thus show that the most recent common ancestor of modern snakes was insectivorous. However, after the disappearance of the dinosaurs, the diet of these animals quickly expanded to include birds, fish and small mammals, that is, groups of vertebrates that also flourished at that time.
“Our work shows how ecological opportunities can shape evolutionary fortunes. In this case, the snakes’ opportunity was to find many vacant ecological niches that had to be filled, ”Grundler tells SINC. And it was that opportunity that seems to have triggered the evolutionary explosion.
“Sometimes those opportunities are generated by extinctions, like the one that wiped out the dinosaurs. Others are caused by the dispersal of an ancestor to another land, as happened with the colubrids when they arrived in South America ”, adds the expert. Thus, when they arrive in new places, they often experience similar bursts of diversifying their diet.
In fact, after the event that wiped out most species, snake diversification slowed, but some bloodlines they kept experiencing new booms of evolution and adaptation.
The scientists used ecological information from the analysis of the stomach contents of specimens kept in museums
To detail the feeding change of the snakes, the scientists used ecological information from the analysis of the stomach contents of specimens preserved in museums. “Until now, it was almost impossible to directly use this type of data in evolutionary analysis. This allows us to capture much more variation and complexity in the diets of snakes, and thus better understand how they have changed, ”says Grundler, who highlights that there is still a long way to go.
“Although our sample includes all the major snake families, it covers less than a quarter of the described species. And a considerable number of these are represented by a handful of observations ”, he concludes. “The reality is that many snakes remain little known ecologically.”
Grundler MC, Rabosky DL (2021). “Rapid increase in snake dietary diversity and complexity following the end-Cretaceous mass extinction”. PLoS Biology 19(10): e3001414. https://doi.org/10.1371/journal.pbio.3001414
Rights: Creative Commons.