MIMICRY – an example of Adaptation DEFINITION The resemblance of one species to another for protective or aggressive purposes Protective against predators Aggressive to act as predators

CRYPSIS - where a species resembles its background or another object or species in order to hide from predators - insects being same colour as resting surface e.g. bark of trees (many moths) - insects resembling leaves or twigs - Insects with eye spots resembling the eyes of owls which are predators of the birds that feed on the insects – to frighten the insectivore

Crypsis resembling leaves

Crypsis resembling predator eyes Normal resting position Disturbed by bird predator

Crypsis – resembling predator eyes

H.W. Bates 1863

BATESIAN MIMICRY - an association in which the members play two different roles - i. the Model – a species which possesses the inherent protection, e.g. poisonous chemicals in insects such as butterflies - ii. The Mimic – a species which lacks the basic protection but through resembling the model superficially gains protection from predators e.g. Monarch (Model) and Viceroy (mimic) butterflies

Monarch (model Poisonous Cardiac glycosides) Viceroy (mimic - edible)

Florida scrub jay eating monarch butterfly then regurgitating Brower 1958

BATESIAN MIMICRY 1. Mimics usually smaller than models 2. Mimicry restricted to females because i) one sex must stay the same to be recognisable, and ii) females do the choosing so males must be the original form 3. Abundance of the mimic is limited by its effectiveness – if too common then predators learn the wrong signal. Numbers increase to point of selective neutrality where benefit equals cost. 4. Polymorphism is common – if morph A is at selective neutrality, a new morph B, mimicking a different model, will be at a selective advantage

Two species of mimics where females are polymorphic resembling three model species

MULLERIAN MIMICRY (from Muller who discovered it) - an association in which all members are protected (e.g. are poisonous) but come to resemble each other, i.e. all are models but resemble each other. - survival increases by sharing the cost of teaching predators that they are poisonous

Mullerian mimics - Amazon forest

MULLERIAN MIMICRY 1. Polymorphism is infrequent, models tend to stay the same because there is a disadvantage in being different – the opposite to that for Batesian mimicry 2. No limit to number of species participating 3. Different colours depend on location and visibility – e.g. groups at different levels in tropical forest have different colours due to different light levels 4. Seen in many caterpillars, adult butterflies in Africa and South America. 5. Can have both Mullerian and Batesian complexes of species

Colours of Mullerian mimics depend on light levels Ground level = low light and dark colours

Colours of Mullerian mimics depend on light levels Upper forest level = high light and red stripes Above canopy = Very high light And red colours

Complex of Mullerian and Batesian mimics

AGGRESSIVE MIMICRY - the visual similarity of a predator/parasite to its prey/host. The predator is the aggressive mimic and the prey/host is the model. - e.g. brood parasites in birds – the parasitic species lays its eggs in the host nest, and both the eggs and the chicks resemble those of the host. African paradise whydah birds lay in the nests of estrildine hosts, and the nestlings look the same so that the host feeds them both.