Designing mate choice experiments

Abstract

The important role that mate choice plays in the lives of animals is matched by the large and active research field dedicated to studying it. Researchers work on a wide range of species and behaviours, and so the experimental approaches used to measure animal mate choice are highly variable. Importantly, these differences are often not purely cosmetic; they can strongly influence the measurement of choice, for example by varying the behaviour of animals during tests, the aspects of choice actually measured, and statistical power. Consideration of these effects are important when comparing results among studies using different types of test, or when using laboratory results to predict animal behaviour in natural populations. However, these effects have been underappreciated by the mate choice literature to date. I focus on five key experimental considerations that may influence choice: (i) should mating be allowed to occur, or should a proxy behavioural measure of preference be used instead? (ii) Should subjects be given a choice of options? (iii) Should each subject be tested more than once, either with the same or different stimuli? (iv) When given a choice, how many options should the subject choose between? (v) What form should the experimental stimuli take? I discuss the practical advantages and disadvantages of common experimental approaches, and how they may influence the measurement of mate choice in systematic ways. Different approaches often influence the ability of animals to perceive and compare stimuli presented during tests, or the perceived costs and benefits of being choosy. Given that variation in the design of mate choice experiments is likely unavoidable, I emphasise that there is no single 'correct' approach to measuring choice across species, although ecological relevance is crucial if the aim is to understand how choice acts in natural populations. I also highlight the need for quantitative estimates of the sizes of potentially important effects, without which we cannot make informed design decisions.Biological Reviews 95 (2020) 759-781

Mate Preference Plasticity in a Critically Endangered Frog: Implications for Conservation Breeding

“…Quantifying the repeatability of mate choice behavior has been identified as an important first step toward understanding how mate preferences vary within populations (Widemo and Saether, 1999;Brooks and Endler, 2001;Dougherty, 2020). Repeatability is defined as the amount of behavioral variation due to differences between individuals, and is calculated by dividing the among-individual variance by the total phenotypic variance (the sum of among-and within-individual variance) (Bell et al, 2009;Dingemanse and Dochtermann, 2013).…”

Meta‐analysis shows the evidence for context‐dependent mating behaviour is inconsistent or weak across animals

“…This means that significant quadratic effects, such as peak signalling at intermediate densities (Kokko & Rankin 2006), will not be captured here. Alternatively, the large variation observed may be the result of methodological differences between studies that have not been accounted for (Dougherty & Shuker 2015; Rosenthal 2017; Dougherty 2020a). For example, studies typically assume animals can accurately assess the costs of expressing a behaviour in a given environment, but this may not always be the case.…”

Does individual personality predict male mating preference for female body size in the Trinidadian guppy?

“…Even though we statistically controlled for male body length, a sexually selected trait in the guppy (Auld et al., 2016), inter‐individual variation in male mating preferences was nonetheless revealed in the current study. Other factors, such as differences in individual genotype and internal state, variation in ecological and social conditions and experimental design and methodology, can potentially generate variation in mating preferences among males at the population level (Dougherty, 2020; Dougherty & Shuker, 2015; Edward & Chapman, 2011; Rosenthal, 2017).…”

“…The above‐noted differences in experimental design, apparatus, measure of mating preference, fish provenance and population evolutionary history likely all contributed to the widely different estimates of repeatability for mating preference based on female body size in male guppies reported in the latter three studies (cf. Dougherty, 2020; Dougherty & Shuker, 2015; Edward & Chapman, 2011; Rosenthal, 2017).…”