Female pipefish can detect the immune status of their mates

Given the ubiquity of the parasites and their important fitness consequences on mate and offspring condition, selection for the ability to distinguish healthy from parasitized potential mates is a key process to enhance Darwinian fitness. In this study, we experimentally evaluated how the immunological experience of two potential partners influences mate choice, using the sex-role-reversed pipefish Syngnathus typhle. We exposed S. typhle to immune challenges with heat-killed Vibrio bacteria and investigated whether the activation of the immune system determined mate preferences. Our results demonstrate that the immune status of the potential partners influenced female mate preference, such that females that were exposed to an immune challenge became choosy and favored unchallenged males. Males, however, did not show any preferences for female immune status. In this context, we discuss mate choice decisions and behavioral plasticity as a complex result of immune challenge, severity of infection, as well as trans-generational effects.