1. 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

2. 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

3. Crypsis resembling leaves

4. Crypsis resembling predator eyes
Normal resting
position
Disturbed by
bird predator

5. Crypsis –
resembling
predator eyes

6. H.W. Bates 1863

7. 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

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

9. Florida scrub jay eating monarch butterfly then regurgitating
Brower 1958

10. 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

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

12. 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

13. Mullerian mimics
- Amazon forest

14. 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

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

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

17. Complex of Mullerian
and Batesian mimics

18. 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.