Aggressive behavior, brain size and domestication in clonal rainbow trout lines.

Area of Science:

• Animal Behavior
• Neuroscience
• Evolutionary Biology

Background:

• Domestication is known to induce significant changes in animal behavior and brain morphology.
• Understanding these changes is crucial for both evolutionary studies and animal welfare.

Purpose of the Study:

• To investigate mirror-elicited aggressive behaviors in rainbow trout clonal lines with varying domestication levels.
• To examine the relationship between brain size, genotype, and domestication.
• To determine if aggressive behavior correlates with brain size in these trout lines.

Main Methods:

• Utilized clonal rainbow trout lines for a reproducible experimental system.
• Performed principal component analyses on 12 continuous variables (behavior, brain/body size) and one discrete variable ('yawn').
• Analyzed aggression syndromes, brain size traits (total brain, olfactory volume) in relation to domestication level and body size.

Main Results:

• Identified distinct aggression syndromes: 'freeze' and 'escape' in highly domesticated lines; 'display' and 'yawn' in wild lines; 'swim against the mirror' in semi-wild and domestic lines.
• Found significant relationships between domestication level and brain size, with domesticated lines exhibiting larger total brain and olfactory volumes after accounting for body size.
• Detected correlations between specific behaviors and domestication levels.

Conclusions:

• Domestication significantly influences aggressive behavior patterns and brain morphology in rainbow trout.
• The identified aggression syndromes and brain size variations provide a foundation for future quantitative trait loci (QTL) mapping studies on domestication-related traits.
• Clonal lines offer a valuable model for dissecting the genetic and developmental underpinnings of domestication effects.