Darwin in 1840, after his return from the voyage

Darwin’s Big IdeaCharles Darwin (1809-1882)

The Voyage of the Beagle

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Figure 22.9

Brusselssprouts

Kale

Selection for leaves

Selection for axillary (side) buds

Selection for apical (tip) bud

Cabbage

Broccoli

KohlrabiWild mustard

Selection for stems

Selection for flowers and stems

"I am almost convinced (quite contrary to the opinion I started with) that species are not (it is like confessing to a murder) immutable."

Charles Darwin, in a letter to Joseph Hooker (January, 1844)

Figure 22.UN02

Observations

Individuals in a populationvary in their heritable

characteristics.

Organisms produce moreoffspring than the

environment can support.

Individuals that are well suitedto their environment tend to leave

more offspring than other individuals.

Inferences

and

Over time, favorable traitsaccumulate in the population.

Figure 22.2

1809

1798

1812

1795

1830

17901809 183136

1844

18591870

Lamarck publishes hishypothesis of evolution.

Malthus publishes“Essay on the Principle

of Population.”

Hutton proposeshis principle of

gradualism.

Charles Darwinis born.

Darwin travels around the world on HMS

Beagle.

The Galápagos Islands

Darwin writes his essay on descent with modification.

On the Origin of Species is published.

While studying species in the Malay Archipelago, Wallace (shown in 1848)sends Darwin his hypothesisof natural selection.

1858Cuvier publishes his extensive studies of vertebrate fossils.

Lyell publishesPrinciples of Geology.

Important Notes• Individuals do not evolve; populations evolve over time• Natural selection can only increase or decrease heritable

traits that vary within a population

• Natural selection does not create new traits, but edits or selects for traits already present in the population

• Adaptations vary with different environments• Local environments determine which traits will be selected

for or selected against in any specific population

• Evolution is supported by an overwhelming amount of scientific evidence

• New discoveries continue to fill the gaps identified by Darwin in The Origin of Species

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