DARWIN

Chapter 16

Evolution Game

Play the game “Who wants to live a million years” on Miss D’s wikispace

If you finish before time is called, click around on the other links (Quiz, Natural Selection, or Darwin’s Bio)

With your partner…

Was the game easy or hard? Explain.Was there a trick to the game? Explain.What mechanism of evolution is this game

explaining?What types of forces cause evolution to

occur?

Darwin’s Theory of Evolution

Darwin is the father of evolution

Evolution = the process of change over time, descent from common ancestors

Evidence: 1. Species vary globally2. Species vary locally3. Species vary over time

Why study tropical areas?

Species vary Globally

Rheas = flightless birds that look and act a lot like ostriches, yet rheas lived in South America

Ostriches lived in AfricaEmu lived in Australia

Darwin noticed that different, yet ecologically similar, animal species inhabited separate, but ecologically similar, habitats around the globe.

Species vary locally

Two species of Rhea’s living in South AmericaSpecies = population that can breed and

produce fertile offspring

Different shell shapes in tortoises of Galapagos

Darwin noticed that different, yet related, animal species often occupied different habitats within a local area

Species vary over time

Darwin collected fossils (preserved remains of animals)

Some fossils of extinct animals were similar to living species.

Ideas that Shaped Darwin’s Thinking

Hutton and Lydell proved that Earth is extremely old and that the processes that changed Earth in the past are the same processes that operate in the present.

Examples?Darwin - If Earth changed over time, could

life too?

Lamarck’s Evolutionary Hypthesis

Read p. 456 with a partner and explain why Lamarck’s ideas were not correct

Malthus’s view

If human population grew unchecked, there would not be enough living space and food for everyone.

Artificial Selection

Artificial selection: the selective breeding of domesticated plants and animals

Shows convincing evidence that humans were playing the role of the environment in nature

Natural Selection

Natural selection the basic mechanism of evolution1. Struggle for existence2. Variation and adaptation3. Survival of the fittest (fitness = survival and reproduction)

Struggle for Existence

Members of a population must compete for food, living space, etc.

Variation and Adaptation

Some variants are better suited than others Faster, longer claws, camouflage, sharper teeth

Adaptation = heritable characteristic that increases organisms ability to survive and reproduce

Bowerbird display

Survival of the Fittest

Differences in adaptation affect fitness (how well an organism can survive and reproduce

Different in rates of survival and reproduction= survival of the fittest

Natural selection

Process by which organisms with variations most suited to their local environment survive and leave offspring

Similar to artificial, but nature is controllingWhen does it occur?

More individual are born than can survive (struggle for existence)

Natural heritable change (variation and adaptation) Variable fitness among individuals (survival of the

fittest)

Natural Selection Myths

Does not make organisms better But does enable them to pass on their genes

Does not move in a fixed direction No one perfect way of doing something, ex pollination

Not the only mechanism that drives evolution

Common descent

According to the principal of common descent, all species – living and extinct – are descended from ancient common ancestors

Evidence?

Evidence of Evolution

1. Biogeography (distribution)2. The Age of Earth and Fossils3. Comparing Anatomy and Embryology

(homologous, analogous and vestigial structures)

4. Genetics and Molecular Biology (amino acid sequences)

Lab – Evidence of Evolution