Adaptive Radiation

Chapter 19

Ecological Niche 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 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

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

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