Covariation among behavioral traits and hatching time in zebrafish

Area of Science:

• Ethology
• Animal Behavior
• Neuroscience

Background:

• Individual variation in behavior is crucial for understanding population dynamics.
• Hatching time in fish can correlate with behavioral differences, potentially reflecting personality types.
• Consistency of these behavioral differences across time and contexts is a key aspect of behavioral personality.

Purpose of the Study:

• To investigate the relationship between hatching time and behavioral consistency in zebrafish (Danio rerio).
• To assess if early-hatching (EH) and late-hatching (LH) zebrafish exhibit distinct behavioral profiles.
• To examine behavioral consistency across different ontogenetic stages (juvenile and adult) and contexts.

Main Methods:

• Zebrafish were categorized into early-hatching (EH) and late-hatching (LH) groups.
• Behavioral tests were conducted at 30 and 120 days post fertilization (dpf).
• Tests included the black-white paradigm (anxiety-like behavior), novel tank paradigm (explorativeness), and novel object paradigm (boldness).

Main Results:

• EH zebrafish showed reduced latency to enter the white area and spent more time in the black area in the black-white test, indicating less anxiety-like behavior.
• EH individuals demonstrated greater explorativeness and boldness in the novel tank and novel object tests, respectively.
• Consistent behavioral differences were observed between EH and LH groups across tested contexts and ontogenetic stages.

Conclusions:

• Hatching time serves as a reliable indicator of consistent behavioral profiles in zebrafish.
• Early hatching is associated with bolder, more explorative, and less anxious behavior.
• These findings contribute to understanding the ontogeny of behavioral personality in fish.