Unexploited females and unreliable signals of male quality in a Malawi cichlid bower polymorphism

Abstract

Complex signals present 2 outstanding questions: why do they exist and how are they interpreted? Multiple signals can be beneficial for the increased diversity or redundancy of information they convey; however, it is not clear how receivers use this additional information. I investigated a lekking Malawi cichlid fish that builds polymorphic bowers; some males build their sand spawning craters on rock platforms, rather than the sand floor, resulting in increased overall height and reduced construction, maintenance, and competition costs. This suggests that rock bowers are an unreliable signal of male investment. Using field observations and in situ bower manipulations I tested fitness costs, female preferences for bower type, bower height, and male displays, and mechanisms for the maintenance of bower polymorphism. In contrast to predictions, observational and experimental data confirmed that females were more likely to visit rock bowers but did not ultimately lay more eggs there. This indicates that females responded to potentially deceptive rock bower males by advancing to the next stage of courtship but were not ultimately fooled by these deceptive signals. Assessing additional signals during the next courtship stage may allow females to counteract initial sensory exploitation or females may be intentionally increasing their investment in mate assessment in response to deceptive signals. Male bower polymorphism may be maintained by the limited availability of rock platforms; there was no evidence for significant variation in individual female preferences or male bower-building strategies. © The Author 2010. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved.