Evolution

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Survival of the Fittest

Key Concept

Over Time, Natural Selection Results In Changes In The Inherited Characteristics Of A Population. These Changes Increase A Species Fitness In Its Environment

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Natural Selection

Cannot Be Seen Directly

It Can Only Be Observed As Changes In A Population Over Many Successive Generations

Radiation

Fossil Record

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Descent With Modification

Takes Place Over Long Periods of Time

Natural Selection Can Be Observed As Changes In

Body Structures

Ecological Niches

Habitats

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Descent With Modification

Species Today Look Different From Their Ancestors

Each Living Species Has

Descended

With Changes

From Other Species

Over Time

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Descent With Modification

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Descent With Modification

Implies

All Living Organisms Are Related

Single Tree of Life

DNA, Body Structures, Energy Sources

Common Descent

All Species, Living & Extinct, Were Derived From Common Ancestors

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Major Problem in Darwin’s Theory

No mechanism to explain natural selection

How could favorable variations be transmitted to later generations?

With the rediscovery of Mendel’s work in the first half of the 20th century, the missing link in evolutionary theory was found

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Opposition to Evolution

The upheaval surrounding evolution began with Darwin’s publication of On the Origin of Species By Means of Natural Selection

The debate continues nearly 150 years later

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Theory of Evolution Today

Supporting Evidence

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Homologous Structures

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Evidence for Evolution - Comparative Embryology

Similarities In Embryonic Development

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Similarities in DNA Sequence

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Evolution of pesticide resistance in response to selection