Alternative reproductive strategies in the ruff, Philomachus pugnax: a mixed ESS?
In the ruff, there are two alternative male reproductive strategies. The majority of males of this lekking bird attempt to establish and defend territories on leks, and are referred to as Independents. Other males, referred to as Satellites, forego this behaviour and instead attempt to get access to the territories defended by Independents by acting submissively. The system is thought to be an example of a mixed evolutionarily stable strategy (ESS), where the two strategies have equal fitness payoffs and are maintained by negative frequency-dependent selection. Satellites visited leks at the same time as females, and were associated with territory-holding Independents which were successful in attracting females. This appeared to be an effect both of Satellites following females, and of females being attracted to Independents that dominated submissive Satellites. Males pursuing the two strategies benefited from the presence of each other, at least to some extent. In this study, Satellites got fewer copulations than expected by their proportion in the population. Satellites on leks might have increased longevity or reproductive life span, and gained copulations off leks and while migrating, to compensate for their low observed mating success on leks. The Satellite strategy may be a low-cost, low-benefit strategy, which may have equal average lifetime reproductive success as the territorial strategy Copyright 1998 The Association for the Study of Animal Behaviour
Widemo
F
Section of Animal Ecology, Department of Zoology, Uppsala University