Lateralization of aggression in fish

Area of Science:

• Ethology
• Neuroscience
• Comparative Psychology

Background:

• Lateralization of aggressive behaviors, specifically left-eye/right-hemisphere dominance, is documented across tetrapods.
• Data on eye-use lateralization in aggressive behaviors for teleost fish (bony fish) has been notably absent.
• Understanding this pattern in fish could reveal conserved or divergent mechanisms of behavioral lateralization.

Purpose of the Study:

• To investigate eye-use lateralization during aggressive interactions in three teleost fish species.
• To determine if teleost fish exhibit a left-eye dominance similar to tetrapods or a different pattern.
• To explore potential reasons for any observed differences in lateralization patterns.

Main Methods:

• Assessed eye preference during mirror-image stimulation (attacking own reflection) in Gambusia holbrooki, Xenotoca eiseni, and Betta splendens.
• Confirmed findings by scoring eye preference during aggressive attacks and displays towards live rivals in two species.
• Quantified lateralization by analyzing which eye was predominantly used during aggressive behavioral contexts.

Main Results:

• All three teleost species (G. holbrooki, X. eiseni, B. splendens) displayed a significant preference for using their right eye.
• This right-eye preference was consistent whether subjects attacked a mirror image or a live rival.
• The observed right-eye dominance in fish is opposite to the established left-eye dominance in tetrapods.

Conclusions:

• Teleost fish exhibit a right-eye dominance in aggressive behaviors, diverging from the left-eye dominance seen in other vertebrates.
• This finding suggests a potentially unique evolutionary trajectory for behavioral lateralization in fish.
• Further research is needed to elucidate the neurobiological and evolutionary underpinnings of this reversed asymmetry.