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Increased signalling effort when survival prospects decrease: male-male competition ensures honesty
1Section of Ecology, Department of Biology, University of Turku
Animal Behaviour
|October 18, 2000
Summary
The handicap principle suggests honest signals have fitness costs. In sticklebacks, poor condition increased red coloration, reducing signal honesty, but male competition enforced honesty on average.
Area of Science:
- Evolutionary Biology
- Animal Behavior
Background:
- The handicap principle posits that honest signals incur fitness costs, ensuring only high-quality individuals can afford exaggerated signals.
- Signal costs can decrease with age, potentially leading to increased signalling as a terminal effort, compromising honesty.
Purpose of the Study:
- To investigate how survival costs and social costs influence the honesty of sexual signals in the three-spined stickleback (Gasterosteus aculeatus).
- To determine if environmental conditions and male-male competition affect the reliability of nuptial coloration as an indicator of male parental ability.
Main Methods:
- Experimental manipulation of male condition to assess its impact on nuptial coloration and egg cannibalism.
- Inclusion of male-male competition to evaluate socially imposed costs on signal expression.
Main Results:
- Males in poor condition exhibited increased red coloration, making the signal less reliable for assessing parental ability.
- Some males in poor condition cannibalized eggs, likely to increase energy reserves.
- Male-male competition reduced signal expression in poorer quality males, enhancing overall signal honesty.
Conclusions:
- Socially imposed costs are crucial for maintaining honest sexual signalling.
- Signal dishonesty can arise when signalling costs are reduced under favorable conditions.
- Environmental context is vital for understanding the evolution and maintenance of honest sexual signals.