The vertebrate social behavior network: evolutionary themes and variations.

Area of Science:

• Neuroscience
• Comparative Biology
• Evolutionary Biology

Background:

• A core social behavior network (SBN) is conserved across vertebrates, including mammals, birds, and teleost fish.
• This SBN, located in the basal forebrain and midbrain, features interconnected nodes with sex steroid hormone receptors involved in social behaviors.
• Evolutionary conservation of the SBN facilitates studying phenotypic behavioral variation using diverse species.

Purpose of the Study:

• To investigate functional variation within the conserved SBN related to divergent social behaviors.
• To explore how natural selection acts on neuroendocrine functions influencing gonadal regulation and behavioral modulation.
• To examine the evolution of SBN components in parallel with sociality divergence and convergence.

Main Methods:

• Utilized a sexually polymorphic fish species to study independent selection on hypothalamic neuroendocrine functions.
• Examined avian social organizations and ecologies, isolating species-typical group size as a variable.
• Analyzed specific brain areas and neuropeptide distributions within the SBN across different taxa.

Main Results:

• Demonstrated independent operation of natural selection on hypothalamic functions for gonadal regulation and behavioral modulation in fish.
• Showcased that specific SBN areas and peptidergic components evolve in parallel with sociality changes in birds.
• Highlighted the functional properties of the SBN adapting to divergent and convergent social structures.

Conclusions:

• The conserved social behavior network provides a powerful model for understanding the neural basis of social behavior evolution.
• Natural selection can independently shape neuroendocrine pathways within the SBN, influencing reproduction and behavior.
• The SBN's adaptability underscores its crucial role in the evolution of diverse social systems across vertebrates.