Mimicry between unequally defended prey can be parasitic: evidence for quasi-Batesian mimicry.
The nature of signal mimicry between defended prey (known as Müllerian mimicry) is controversial. Some authors assert that it is always mutualistic and beneficial, whilst others speculate that less well defended prey may be parasitic and degrade the protection of their better defended co-mimics (quasi-Batesian mimicry). Using great tits (Parus major) as predators of artificial prey, we show that mimicry between unequally defended co-mimics is not mutualistic, and can be parasitic and quasi-Batesian. We presented a fixed abundance of a highly defended model and a moderately defended dimorphic (mimic and distinct non-mimetic) species, and varied the relative frequency of the two forms of the moderately defended prey. As the mimic form increased in abundance, per capita predation on the model-mimic pair increased. Furthermore, when mimics were rare they gained protection from predation but imposed no co-evolutionary pressure on models. We found that the feeding decisions of the birds were affected by their individual toxic burdens, consistent with the idea that predators make foraging decisions which trade-off toxicity and nutrition. This result suggests that many prey species that are currently assumed to be in a simple mutualistic mimetic relationship with their co-mimic species may actually be engaged in an antagonistic co-evolutionary process.
Department of Evolution, Ecology and Behaviour, Institute of Integrative Biology, Faculty of Health and Life Sciences, Biosciences Building, University of Liverpool, Crown Street, Liverpool L697ZB, UK. h.m.rowland@liv.ac.uk
Hannah M
HM
Rowland
Johanna
J
Mappes
Graeme D
GD
Ruxton
Michael P
MP
Speed
D000818:Animals; D005518:Food Preferences; D006790:Host-Parasite Interactions / Q000502:physiology*; D046109:Passeriformes / Q000502:physiology*; D011235:Predatory Behavior / Q000502:physiology*