Evolution

Evolution

• Evolution- changes that have transformed life over time

• Biological Diversity= variety of living things• How did different organisms arise?• How are they related?

• Charles Darwin- (1831) – naturalist– HMS Beagle– Galapagos islands- studied finches– Book: (1858) The Origin of Species

Patterns of Diversity

• Organisms well suited to environment• Why were dif animals in similar environments

at dif parts of the world?

Living Organisms and Fossils

• Fossils-preserved remains of ancient animals• Some fossils had similarities of living org. • How were these fossil species related to living

organisms?

Galapagos Islands

• Dif Climates• Tortoise’s differed on each island in

predictable ways• Birds differed on islands

• Were animals on dif islands once from the same species?

Scientists

• Buffon- (1700) earth older than 1,000 years– Fossils and living organisms similar but not exactly

the same• Lamarck- (1800)proposed life evolves or

changes– Evolution was a process of adaptation– by use or disuse organisms lost /acquired traits– Traits were passed on

• Hutton/Lyell(1830)- geological change• Earth changed over time– erosion– shift in plate

• Malthus-(1798) Principle of Populations– More offspring are produced than can survive

• Wallace- (1858) mechanism of evolutionary change

On the Origin of Species

1. Variation among species– Artificial selection- nature provided variation and

humans selected those variations to be more useful.

2. Struggle for existence- more offspring produced than can survive

• Those more suited for the env. Survived and passed on traits

3. Survival of the Fittest- Natural Selection• Fitness- ability of an organism to survive and

reproduce• Adaptation- inherited characteristic that

increases an organisms chance of survival/reproduce

4. Natural Selection- mechanism of evolution– Traits are selected by nature– Traits passed on to offspring, trait increases over

time– Over time population changes Over time natural selection results in changes in

inherited characteristics of a population

5. Descent with Modification- each living species has descended with changes from other species over time

• Change- change in environment

– Changes in different environments– Ex: Rabbits

Evolution Evidence

1. Fossil Record- document intermediate stages of life

2. Geographic Distribution of Living Species-• Many environments similar= same pressures

of natural selection= different animals evolved common features

3. Homologous Body Structure- structures that evolved from a single structure in a common ancestor.

Vestigial organs-Organs reduced in size only traces left

4. Similarities in embryology- embryos similar at various stages of development

Natural Selection

• Trait must be inherited• Variation- difference among members of the

same species• More offspring produced than can survive

• Evolution occurs over time, populations evolve not individuals