Adaptation

Ch 15 section 2

Results in adaptation – a population becomes better suited to its environment

Adaptation can also refer to a derived trait, one that has come about by natural selection.

Natural Selection

VOCAB Any ___________________ thatincreases an organism’s ______________ = _____________

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ADAPTATION

inherited characteristicchance of survival

Camouflage-the ability to belnd in with your environment

Allows organisms to become almost invisible to predators

Mimicry-one species evolves to resemble another species

Plant adaptations• Tropisms- a plants growth response

to an external factor.• 3 types

– Phototropism– Gravitropism– Thigmotropsim

Phototropism

• Plant growth in response to light

GravitropismPlant Growth in response to gravity

Thigmotropsim

• Growth/movement in response to touch

• Ex:vines

Sources of Variation • Mutations or genetic changes

occur infrequently in a cell but frequently in a population, particularly a large one.

• Genetic recombination through sexual reproduction, including crossing-over during meiosis.

SPECIATION AND PATTERNS IN EVOLUTION

Pages 438-441

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Speciation: The Formation of a new species

Speciation• When some members of a

population become separated from the group and change so much that they can no longer mate with members of the original population.

• 2 Types:1. Allopatric Speciation2. Sympatric Speciation

Allopatric Speciation

• A physical Barrier divides a population which gives rise to a new species.– Takes a LONG time– Most common

Sympatric speciation• A new species forms without a

physical barrier.– Usually occurs in plants