Computational mate choice: Theory and empirical evidence

Abstract

a b s t r a c tThe present review is based on the thesis that mate choice results from information-processing mechanisms governed by computational rules and that, to understand how females choose their mates, we should identify which are the sources of information and how they are used to make decisions. We describe mate choice as a three-step computational process and for each step we present theories and review empirical evidence. The first step is a perceptual process. It describes the acquisition of evidence, that is, how females use multiple cues and signals to assign an attractiveness value to prospective mates (the preference function hypothesis). The second step is a decisional process. It describes the construction of the decision variable (DV), which integrates evidence (private information by direct assessment), priors (public information), and value (perceived utility) of prospective mates into a quantity that is used by a decision rule (DR) to produce a choice. We make the assumption that females are optimal Bayesian decision makers and we derive a formal model of DV that can explain the effects of preference functions, mate copying, social context, and females' state and condition on the patterns of mate choice. The third step of mating decision is a deliberative process that depends on the DRs. We identify two main categories of DRs (absolute and comparative rules), and review the normative models of mate sampling tactics associated to them. We highlight the limits of the normative approach and present a class of computational models (sequential-sampling models) that are based on the assumption that DVs accumulate noisy evidence over time until a decision threshold is reached. These models force us to rethink the dichotomy between comparative and absolute decision rules, between discrimination and recognition, and even between rational and irrational choice. Since they have a robust biological basis, we think they may represent a useful theoretical tool for behavioural ecologist interested in integrating proximate and ultimate causes of mate choice.

Context-dependent evaluation of prospective mates in a fish

“…On a theoretical level, the comparative evaluation of prospective mates is expected to have been favoured in species where simultaneous encounters of males are common (Castellano et al 2012). With this respect, in the green swordtail (Royle et al 2008), the fiddler crab (Reaney 2009) and the peacock blenny, i.e.…”

“…In many species, females base their mating decisions on several male signals (Candolin 2003; Hebets and Papaj 2005); yet, how they combine the different male attributes to rank potential mates (Bateson and Healy 2005; Castellano et al 2012) is not fully understood.…”

Mate choice decision rules: Trait synergisms and preference shifts

“…In broad terms, multiple ornaments may be evaluated either sequentially or simultaneously (reviewed in Castellano, Cadeddu, & Cermelli, 2012). Sequential choice occurs, for example, where males advertise for mates using both long-distance signals such as acoustic traits and short-distance signals, such as visual displays (Gibson, 1996).…”

Preys’ exploitation of predators’ fear: when the caterpillar plays the Gruffalo

“…We made two main assumptions about these mechanisms. First, we assume that noisy evidence for the testing hypotheses is accumulated over time and that a decision is made when the evidence for one of the hypotheses reaches a critical threshold [10][11][12][18][19][20]. Second, we assume that, during assessment of prospective preys/predators, the bird makes the two alternative hypotheses (caterpillar/not-caterpillar; snake/not-snake) to compete against each other.…”

“…To investigate this hypothesis, we develop a sequential-sampling model of decision-making [10][11][12]. In this model, decision-makers integrate noisy evidence over time and make decisions when the accumulated evidence reaches a given threshold.…”