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Adaptive Radiation
Chapter 19
Ecological Niche
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The role an organism plays within a community
Includes feeding, habitat, competitors, enemies
etc
Darwin’s finches
- Galapagos Islands, 1831
- found many different species
- large variety of beak size & shape
- occupied many different niches (lack of
competitors)
- speciation lead to sub-populations
- each became diversified and adapted to their
niche
Adaptive Radiation
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Evolution of a group of related organisms along
several different lines
- over a long period of time
- to a wide variety of environments
1) marsupials in Australia
- evolved into a variety of niches
- no threat of competition from mammals
2) British buttercups
- 3 species
- all suited to different soil moistures
Homology & Divergent evolution
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Homologous structures
- same evolutionary origin
- structurally alike
E.g. mammals have pentadactyl (5 digit) limbs
- limb has evolved to suit different functions
(digging in moles, swimming in whales)
This is divergent evolution
Convergent evolution
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Animals that have similar structural
features, but are from different ancestors
E.g. european/strand moles are placental,
marsupial mole is marsupial
Evolve this way to suit their chosen niche