Tick parasitism as a cost of sexual selection and male parental care in a Neotropical frog

Abstract

Sexual selection can drive variation in conspicuous traits, providing signals to females about overall male health including their ability to fight parasites. Trait–parasite relationships have been extensively studied in fish and birds, but few records exist for amphibians. Here, we focused on a direct-developing frog (Eleutherodactylus cooki) that exhibits variation in the extent of yellow coloration on the venter of males, a sexually selected trait that is correlated with reproductive success and parental care. We quantified the relationship between the color trait and the prevalence of two parasites, a tick (Carios undescribed sp.) and a fungal pathogen (Batrachochytrium dendrobatidis), across hosts, populations, and environmental contexts. We found that tick larvae were carried more frequently by males than females. Among males, ticks parasitized more those with a greater extent of yellow coloration. We did not detect any patterns associated with sex, habitat use, or male coloration with fungal infections. Co-infections were low (5%) and predominantly occurred in males (71%). Our findings highlight the reproductive cost of tick parasitism for males and suggest that females may assess both the quality of parental care and overall health in areas of high tick exposure. Thus, yellow coloration in males of this nocturnal amphibian may have evolved as an honest signal of health and quality of parental care.