Mate choice is a key factor driving the evolution of signal design in many vertebrate and invertebrate systems. Most empirical studies of mate choice, however, have ignored two facts about signals. First, individual signalers rarely produce their signals exactly the same way each time. Second, signals consist of multiple components. Hence, in the real world, signals vary simultaneously along multiple dimensions within individuals. We are interested in understanding how this multivariate signal variation impacts mate choice decisions, especially in noisy, "real-world" environments.

Using laboratory phonotaxis tests (see adjacent video), in which females respond to synthetic models of male advertisement calls, we have measured a number of univariate female preference functions for various call properties in Cope’s gray treefrog (Hyla chrysoscelis). We have now shown that females have a stabilizing preference for pulse rate (Kuczynski et al 2010; Nityananda & Bee 2011; Ward et al. 2013a), directional preferences for faster call rates (Ward et al. 2013b), longer call durations (Bee 2008; Ward et al. 2013b; Vélez et al. 2013), higher overall call efforts (= call rate x call duration) (Ward et al. 2013b), and higher call amplitudes (Bee et al. 2012), and a threshold preference against low-frequency calls (Schrode et al. 2012). We are now turning our attention to the question of how multiple components of advertisement calls are weighted in mate choice decisions when there is simultaneous variation in more than one property. We have done this by measuring multivariate selection on males calls via female mate choice (Tanner et al. 2017). Ongoing work is now investigating the extent to which natural levels of intra-individual variation in male signals impacts female mating decisions. Stay tuned for more on this research!