Multiple Visual Cues, Receiver Psychology, and Signal Evolution in Pygmy Swordtails

" Females typically attend to complex, multi-dimensional suites of traits when evaluating mates. There have been relatively few studies addressing how females evaluate and integrate multiple male signal components. We analyzed a large data set of simultaneous mate choice trials on female Xiphophorus multilineatus and X. pygmaeus, in which females chose between male signal combinations rendered on three-dimensional computer animations of males. Stimuli were based on population samples of two distinct male morphs: large, courting males, and small, “sneaker” males. Traits were selectively removed from large males and presented against a standard large male animation, or added to small males and presented against a standard small male. We addressed how female responses to these multivariate male trait complexes are correlated within individual females, how females weight different traits, and how trait context (traits removed from a small male or added to a large male) influences female response. Intra-female correlations among responses were not detected, and correlations across traits overall were weak. In general, females exhibited directional preferences for male traits, and the influence of each trait on female preference was consistent with additivity. There was no overall relationship between the context in which a trait was presented and female preference "