Brain Allometry Across Macroevolutionary Scales in Squamates Suggests a Conserved Pattern in Snakes

Area of Science:

• Evolutionary biology
• Comparative neuroanatomy
• Vertebrate paleontology

Background:

• Limited research exists on brain size variation in squamate reptiles (snakes and lizards).
• Understanding brain allometry is crucial for insights into vertebrate evolution.

Purpose of the Study:

• To analyze macroevolutionary patterns of brain allometry in snakes and lizards.
• To investigate potential energetic trade-offs related to relative brain size in vipers.

Main Methods:

• Comparative analysis of brain size relative to body mass and snout-vent length in snakes and lizards.
• Assessment of organ size trade-offs in Crotalinae vipers.

Main Results:

• Snakes displayed conserved brain allometry with body mass, while lizards did not.
• Body length influenced brain allometry in both groups, with less variation in snakes.
• No evidence of energetic trade-offs between brain size and other organs was found in vipers.

Conclusions:

• Snakes show remarkably low variation in brain allometry across taxa, despite body elongation.
• The conserved snake body plan may play a role in balancing energetic demands during brain and body size evolution.
• Further research is needed to elucidate the mechanisms behind conserved brain allometry in snakes.