Relative size and chemical information impact mixed-sex contests in the crayfish Faxonius rusticus Girard, 1852 (Decapoda: Astacidea: Cambaridae)

Male and female differences in contest strategies present a valuable exploration of varied access to relevant ecological information. Crayfish studies have revealed that males and females likely use different sources of information to dictate contest persistence and the difference becomes most apparent in mixed-sex contests. We examined the role of chemical information in mixed-sex contest dynamics and assessment by randomly pairing mixed-sex pairs that were either size-matched or size asymmetric. The lesion treatments consisted of eliminating olfactory cells on the antennules, the main organ for chemical detection in crayfishes. Dyads were classified as control (both intact), female-lesioned (females lesioned, males intact), or male-lesioned (females intact, males lesioned). Statistical analysis revealed that sex-based size difference, lesion treatment, and winner's sex dictated contest duration. Regressions did not reveal evidence of one particular assessment strategy for control dyads, but male- and female-lesioned contests demonstrated weak relationships indicative of a possible self-assessment strategy. Behavioral network analyses indicated that chemical information is important for transitions between behavioral states and that the sexes use this information differentially. We suggest chemical information is important for both males and females in contest assessment, but the information contained in the signal or how the participants use the information for assessment likely differs across the sexes.