AIM: How does evolution

explain the diversity in the world?

Warm – up: Give your definition of

“evolution”

What is Evolution?n Species living today are descended

from species that lived in the past.n Evolution is the change over time in

the heritable characteristics in a population from simple to complex.

Charles Darwin

Charles Darwinn Naturalist on HMS Beagle (1831 –

1836)

Charles Darwinn Naturalist on HMS Beagle (1831 –

1836)n Observed the coastline of South

America

Charles Darwinn Naturalist on HMS Beagle (1831 –

1836)n Observed the coastline of South

American Explored and observed organisms on

the Galapagos Islands

Charles Darwinn Naturalist on HMS Beagle (1831 –

1836)n Observed the coastline of South

American Explored and observed organisms on

the Galapagos Islandsn Compared his observations between

the two areas which led him to develop his idea of natural selection.

Charles Darwinn Naturalist on HMS Beagle (1831 –

1836)n Observed the coastline of South

American Explored and observed organisms on

the Galapagos Islandsn Compared his observations between

the two areas which led him to develop his idea of natural selection.

n Believed all species evolved from 1 ancestral type (common origins)

Theory of Natural Selection

Theory of Natural Selectionn Natural variation: In a population, there are organisms

with varying characteristics that are able to be inherited by offspring.

Theory of Natural Selectionn Natural variation: In a population, there are organisms

with varying characteristics that are able to be inherited by offspring.

n Overproduction: Organisms produce more offspring that are required to replace their parents and that can possibly survive.

Theory of Natural Selectionn Natural variation: In a population, there are organisms

with varying characteristics that are able to be inherited by offspring.

n Overproduction: Organisms produce more offspring that are required to replace their parents and that can possibly survive.

n Stabilization: Populations remain relatively constant with no population getting indefinitely large.

Theory of Natural Selectionn Natural variation: In a population, there are organisms

with varying characteristics that are able to be inherited by offspring.

n Overproduction: Organisms produce more offspring that are required to replace their parents and that can possibly survive.

n Stabilization: Populations remain relatively constant with no population getting indefinitely large.

n Struggle for Existence: Competition for limited resources, struggle to avoid predation and disease.

Theory of Natural Selectionn Natural variation: In a population, there are organisms

with varying characteristics that are able to be inherited by offspring.

n Overproduction: Organisms produce more offspring that are required to replace their parents and that can possibly survive.

n Stabilization: Populations remain relatively constant with no population getting indefinitely large.

n Struggle for Existence: Competition for limited resources, struggle to avoid predation and disease.

n Survival of the Fittest: Individuals that are best adapted to their environment will have a selective advantage.

Theory of Natural Selectionn Natural variation: In a population, there are organisms

with varying characteristics that are able to be inherited by offspring.

n Overproduction: Organisms produce more offspring that are required to replace their parents and that can possibly survive.

n Stabilization: Populations remain relatively constant with no population getting indefinitely large.

n Struggle for Existence: Competition for limited resources, struggle to avoid predation and disease.

n Survival of the Fittest: Individuals that are best adapted to their environment will have a selective advantage.

n Selective Advantage: More likely to survive and reproduce than other less well-adapted organisms.

Neo - Darwinism

n Incorporation of new scientific evidence (genetics & molecular biology)

n Has shown that natural variation stems from mutations in reproductive cells