Kin selection and cooperative courtship in wild turkeys

Area of Science:

• Behavioral Ecology
• Evolutionary Biology
• Ornithology

Background:

• Cooperative breeding systems in birds often involve subordinate males assisting dominant individuals.
• The evolutionary drivers for such altruistic behavior, particularly when direct reproductive benefits are absent, remain a key question.
• Hamilton's kin selection theory offers a potential explanation through indirect genetic benefits.

Purpose of the Study:

• To investigate the role of kin selection in the evolution of cooperative courtship in wild turkeys.
• To determine if subordinate males gain indirect fitness benefits by helping related dominant males.
• To test the applicability of Hamilton's rule in a controversial case of avian cooperation.

Main Methods:

• Utilized genetic measures to assess relatedness between subordinate (helper) and dominant males.
• Quantified reproductive success of both helper and dominant males.
• Calculated indirect fitness gains for helpers based on relatedness and the reproductive success of their relatives.

Main Results:

• Subordinate males in wild turkey courtship partnerships were found to be related to the dominant males they assisted.
• Helper males did not achieve direct reproduction but accrued significant indirect fitness benefits.
• Calculated indirect fitness gains, according to Hamilton's rule, exceeded the costs of helping.

Conclusions:

• Kin selection provides a robust explanation for the evolution of cooperative courtship in wild turkeys.
• This study confirms a long-standing, yet previously controversial, example of kin selection in avian systems.
• Findings extend the understanding of male relatedness and kin-selected benefits in lekking species.