Dipsadine snakes have skulls that evolve to fit their needs

Researchers at The University of Texas at Arlington have found that the skulls of dipsadine snakes are strongly correlated with their habitat and diet. 

The study reveals that, in these Central and South American snakes, skull shape has evolved and adapted to meet their needs. 

Study significance

Gregory Pandelis from UTA’s Amphibian and Reptile Diversity Research Center emphasized the significance of this study.

“We now have evidence that this group of snakes is one of the most spectacular and largest vertebrate adaptive radiations currently known to science,” said Pandelis.

“We found that both habitat use and diet preferences are strongly correlated to skull shape in this group of snakes, indicating these are likely factors driving cranial evolution for these species.”

Dipsadine snakes

Dipsadine snakes vary in size from less than 12 inches to over 9 feet. They have dietary preferences that range from larger animals like birds and frogs to smaller prey such as frog eggs and worms. 

“Dipsadine snakes represent one of the most spectacular vertebrate radiations that have occurred in any continental setting, with over 800 species in South and Central America,” wrote the study authors. 

“Their species richness is paralleled by stunning ecological diversity, ranging from arboreal snail-eating and aquatic eel-eating specialists to terrestrial generalists.”

Focus of the study

The study was focused on skull evolution and its functional significance for snakes, especially considering their lack of limbs. The skull shape is crucial for prey acquisition, ingestion, navigating habitats, mate selection, and defense against predators. 

Snakes’ skulls enable them to maneuver through their environment and consume prey much larger than their size would suggest.

How the research was conducted 

To analyze skull evolution, the team created 3D digital reconstructions of 160 dipsadine snake skulls using X-ray microcomputed tomography-scanning (CT scanning) of museum specimens. 

They combined this with geometric morphometrics and field data on the snakes’ lifestyles and diets to examine the relationship between skull shape and ecology.

Critical insights

“Our research shows that snakes that are aquatic (water) or fossorial (underground dwellers) seem to have the strongest selective pressure on their skulls, and evolutionary convergence is rampant among these groups,” explained Pandelis. 

“There are only a few good evolutionary solutions to the difficult problems of trying to move through dirt and water efficiently.” 

Pandelis said the study provides important insights into how snakes adapt to their highly unique ways of eating and inhabiting their environments, although there is much that we still don’t know about these enigmatic and fascinating animals.

Study implications

“Both habitat and dietary ecology are significantly correlated with skull shape in dipsadines; the strongest relationships involved skull shape in snakes with aquatic and fossorial lifestyles,” wrote the study authors.

“This association between skull morphology and multiple ecological axes is consistent with a classic model of adaptive radiation and suggests that ecological factors were an important component in driving morphological diversification in the dipsadine mega radiation.”

The study is published in the journal BMC Ecology.

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