Modeling strategic sperm allocation: Tailoring the predictions to the species

Abstract

Two major challenges exist when empirically testing the predictions of sperm allocation theory. First, the study species must adhere to the assumptions of the model being tested. Unfortunately, the common assumption of sperm allocation models that females mate a maximum of once or twice does not hold for many, if not most, multiply and sequentially mating animals. Second, a model's parameters, which dictate its predictions, must be measured in the study species. Common examples of such parameters, female mating frequency and sperm precedence patterns, are unknown for many species used in empirical tests. Here, we present a broadly applicable model, appropriate for multiply, sequentially mating animals, and test it in three species for which data on all the relevant parameter values are available. The model predicts that relative allocation to virgin females, compared to nonvirgins, depends on the interaction between female mating rate and the sperm precedence pattern: relative allocation to virgins increases with female mating rate under first-male precedence, while the opposite is true under later-male precedence. Our model is moderately successful in predicting actual allocation patterns in the three species, including a cricket in which we measured the parameter values and performed an empirical test of allocation.

Chris Cannings: A Life in Games

“…They again found a unique ESS for each case, where this could either be monomorphic guarding, a monomorphic population of non-guarders with a single s strategy (as in the original model where guarding was not allowed) or much more rarely a polymorphic mixture of guarding and a range of non-guarding strategies. An interesting recent model [160] made similar predictions to the above and was fitted with some success to data for three species.…”

Conceptual developments in sperm competition: a very brief synopsis

“…More biologically realistic models assume that sperm competition levels follow continuous probability distributions; this, however, reduces their mathematical tractability (e.g. [45]). Caution is required to ensure that model assumptions are met when interpreting experimental results [45,46].…”

“…[45]). Caution is required to ensure that model assumptions are met when interpreting experimental results [45,46]. Perhaps ironically, the large sperm allocation theory literature predominantly assumes raffle-based sperm competition, while the most detailed quantitative evidence relates to a quite different mechanism-indirect sperm displacement in yellow dung flies, Scathophaga (= Scatophaga) stercoraria.…”