Alternative Mating Tactics and the Law of Diminishing Returns: The Satellite Threshold Model

The mating systems of many species comprise at least 2 alternative male mating tactics - broadly termed "Dominant" and "Satellite" tactics here. But, there exists no satisfactory conceptual framework in which to explain their co-occurrence and persistence. A Dominant male's ability to copulate is a positive, but decelerating, function of either his territory's attractiveness or his own attractiveness to females. This 'Diminishing Returns Effect' affords mating opportunities for Satellite males associated with the most attractive sites (or males). A graphical Satellite Threshold Model, analogous to the Polygyny Threshold Model (Orians 1969), is developed to predict quantitatively the presence or absence of Satellite male tactics. Five predictions of the Model are supported quantitatively by data from dragonfly and anuran social systems and, more generally, by evidence from a wide variety of species. The Model should apply both to circumstances in which males are able to alternate between tactics and the instances in which males make an irrevocable tactical 'decision'.