Visual cues used by ant-like jumping spiders to distinguish conspecifics from their models

Abstract

Despite the conceptual appeal of how morphological mimics visually distinguish between conspecifics and their models, scant attention has been given to this topic. Accurate discrimination between ants and conspecific spiders is likely to be under strong selection because approaching an ant may result in the spider's death, while approaching a different sex conspecific may result in copulation. I addressed this question by examining responses of the ant-like jumping spider Myrmarachne bakeri Banks 1930 (Salticidae) toward motionless, odorless lures made from dead conspecifics, ants, or lures using components of non-ant-like salticids, ant-like salticids and ants. I found that chelicerae, legs I and body, but not movement, are important cues used by M. bakeri to distinguish conspecifics from ants, but the relative importance of these cues differs depending on a spider's sex. Batesian mimicry is possibly the best-documented example of a deceitful signal, and while the effects of these signals on predators have received considerable attention for over a century (Bates 1862; Wickler 1968; Ruxton et al. 2004) there is scant information on the effects of mimetic signals on conspecifics. This gap in our knowledge is not reflected in the importance of the issue at hand: Batesian mimics resemble an unpalatable or dangerous model, and mimicry has evolved due to its effect on potential predators, which consequently avoid the mimic (Edmunds 1974). However, all animals capable of processing information in the specific sensory modality of the mimetic signal may be fooled by mimics- not just predators. Consequently, if a mimic is a visually guided animal, and it looks like its model, conspecifics themselves may be fooled about its identity. This may be especially pertinent if the model is dangerous to the mimic itself.