Data from: Multivariate phenotypic selection on a complex sexual signal

Animal signals are complex, comprising multiple components that receivers
may use to inform their decisions. Components may carry information of
differing value to receivers, and selection on one component could
modulate or reverse selection on another, necessitating a multivariate
approach to estimating selection gradients. However, surprisingly few
empirical studies have estimated the strength of phenotypic selection on
complex signals with appropriate design and adequate power to detect
non-linear selection. We used phonotaxis assays to measure sexual
selection on the advertisement signal of Cope's gray tree frog, Hyla
chrysoscelis. Female preferences were assessed for five signal components
using single-stimulus and two-stimulus behavioral assays. Linear,
quadratic, and correlational selection gradients were estimated from the
single-stimulus data. Significant directional selection is acting on call
duration, call rate, pulse rate, and relative amplitude; stabilizing
selection is acting on call duration and call rate. Under the two-stimulus
paradigm, conclusions were qualitatively different, revealing non-linear
selection on all components except call duration. For individual subjects,
the outcomes of single-stimulus and two-stimulus trials were frequently
discordant, suggesting that the choice of testing paradigm may affect
conclusions drawn from experiments.