Subterranean Fishes of the World

5642

2022

AIM 2022

46

Laterality in terms of morphology, behavior, and sensory system is well established across animal taxa: L-R disposition of the visceral organs in humans, and the brain lateralization (left and right hemispheres are responsible for different tasks) in birds, rats, and humans. Despite the advantages conferred by laterality (escaping from predators, etc.), not much knowledge exists regarding the origin and evolution of asymmetry in response to environmental demands. We used Astyanax mexicanus, a Mexican tetra composed of two interfertile morphotypes, surface fish and cavefish, to address the evolution of laterality. A trait commonly present in cavefish, but less frequently observed in surface fish, is Vibration Attraction Behavior (VAB), a foraging behavior mediated by the superficial neuromasts (SN). Our previous studies showed a positive correlation between the left SN number and VAB level in Pachón cavefish. Here we addressed if this sensory laterality is present in two other cave populations, Tinaja and Los Sabinos. To achieve this goal, we assessed VAB laterality across surface fish and cavefish populations by developing a new detection method for fish positions via DeepLabCut. Our results revealed that only the Pachón cave population has sensory laterality. No left-right asymmetry for VAB was found across surface and cave populations, however, the L-R behavioral bias was observed at the individual level. VAB increased after starvation in Tinaja cavefish with a right bias, both before and after starvation. Our field experiments support that VAB laterality changed across different populations over time. These results indicate that the laterality observed in the sensory usage and the laterality in the behavioral output are independent of each other and that different cavefish populations evolved distinct laterality modalities. Lastly, we present a mathematical model explaining the advantages of sensory and behavior laterality in food-limited environments.

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