Multimodal female mate choice in a polymorphic flat rock lizard

Sexual selection is a driver of morphological and behavioral diversity. It may also play a role in the maintenance of behavioral and morphological polymorphisms. Adaptive theory predicts that males advertise individual quality through one or more signal paths and that females choose better quality mates based on those signals. Here, we use mate choice experiments in two different signaling modes (chemical and visual), to test whether females of a color cryptic-polymorphic lizard have a preference between two co-occurring male morphs (black and yellow) with alternative behavioral types. We test whether females use visual (males' coloration) and/or chemical cues to choose male morphs. Furthermore, we assess whether continuous costly color expression influences female choice and whether male conspicuousness in their natural background predicts female mate choice. We show that females prefer the aggressive black-morph males based on chemical cues. Females prefer more conspicuous males as mates, and coloration at polymorphic ventral part of the body also contributes to higher conspicuousness of these males. Our study adds to the knowledge of intersexual selection for multi-component signals and opens possibilities for future research to explore the roles of complementary signal modes. Significance statement Sexual selection can drive the evolution of a great diversity of behavioral and morphological features and has puzzled naturalists ever since Darwin. We studied sexual selection in the striped lava lizard (Tropidurus semitaeniatus), a species endemic to Northeast Brazil. This species is known to have two different "types" of males (yellow or black). In our study, we conducted mate choice experiments to test whether females prefer males based on chemical and/or visual cues. Black males tend to be more aggressive and dominant, and we showed that females prefer these males based on their scent. We show that females prefer males that are more conspicuous within their natural habitat, and that ventral polymorphic coloration is related to female preference. Our study highlights the complexity of animal signals and contributes to our understanding of sexual selection and the role of complementary signal modes.