Kin-mediated plasticity in alternative reproductive tactics

Conditional strategies occur when the fitness payoff an individual receives from expressing a given phenotype (from a range of two or more possible phenotypes) is contingent upon that individual’s environmental circumstances. This conditional strategy model underlies many cases of alternative reproductive tactics, in which individuals of one sex employ different means to obtain reproductive opportunities. How genetic relatedness and indirect fitness effects could affect the expression of alternative reproductive tactics remains unexplored. Here, we address this gap using the Acarid mite Rhizoglyphus echinopus, in which large males develop into aggressive ‘fighters’ and small males develop into non-aggressive ‘scramblers.’ Because fighters kill their rivals whereas scramblers do not, fighters should incur a greater indirect fitness cost when competing with their relatives, and thus the expression of the fighter phenotype could be reduced in the presences of relatives. To test this, we ra...