Intralocus Tactical Conflict and the Evolution of Alternative Reproductive Tactics

Alternative reproductive tactics (ARTs) are characterized by consistent and discrete variations in the reproductive behaviors (e.g. mating, fighting, and nesting) of members of the same sex. Selection against intermediate expression of reproductive traits (disruptive selection) can lead to the evolution of ARTs, and can generate intralocus tactical conflict (IATC) when traits that are homologous across ARTs are not at their adaptive optimum. As the sexes and ARTs are both examples of discrete alternative phenotypes, much of what we have learned about intralocus sexual conflict can be applied to ARTs. We outline three criteria necessary to demonstrate IATC and discuss methods for testing these criteria. By determining the extent to which traits involved in ARTs are experiencing IATC, we will gain a better understanding of the benefits of behavioral plasticity, the extent to which both morphological and behavioral traits involved in ARTs are not at their phenotypic optimum, and the extent to which release from IATC can explain the relationship between ARTs and speciation. In addition, IATC may improve our understanding of the relationship between sexual and tactical dimorphism.