What is Evolution?

Evolution is the progressive change in organisms or

species over time.

Early Scientists…Early Scientists…Early Scientists…Early Scientists…

Ernest Von Baer- in early 1800’s discovered egg cells; began comparing embryos and noticed similarities within species

Early Scientists…Early Scientists…Early Scientists…Early Scientists… Jean Baptiste LaMarck- in

early 1800’s explained evolution of species based on Theory of Acquired Traits (if an organism acquires certain traits during its lifetime it will pass them on to its offspring); example: muscles

This theory was proven false!!!

1744-1829

According to LaMarck…

Then came Charles DarwinThen came Charles DarwinThen came Charles DarwinThen came Charles Darwin Born 1809 Studied at Edinburgh and Cambridge 1825-1831

Was going to become a doctor but hated the sight of blood

Studied to become a pastor at his church

Invited on a Voyage of the Beagle 1831-36

‘The Origin of Species’ was published- 1859

Died 1882Darwin’s home at Down, near London

Darwin’s Voyage

A reconstruction of the HMS Beagle sailing off Patagonia.

The Beagle

The Voyage of the Beagle

Galapogos Islands - 1835Galapogos Islands - 1835Galapogos Islands - 1835Galapogos Islands - 1835

Darwin was interested in natural history and made careful observations while on his voyage

Did not recognize significance until back in England, 1837.

Turtles & finches were key evidence

Birds on different islands had different traits:

Darwin’s Observations

Because the food supply was different on the different islands, Darwin theorized that the finches’ beaks were an adaptation.

Charles DarwinCharles DarwinCharles DarwinCharles Darwin

Developed ‘Theory of Natural Selection’ based on his observations from the Beagle voyage of 1831-1836

Darwin observed similarities in species of the Galapagos (ie. finches) and stated that they all evolved from a common ancestor but have adapted based on food availability

Charles Darwinand the

Theory of Natural

Selection

Evolution’s Core Principle

Natural selection-states that organisms with traits best suited for the environment survive and reproduce

“Survival of the Fittest”

Darwin’s Theory of Evolution

1. Overproduction

Organisms produce more offspring than can survive.

Limiting factors include food, space, shelter, predators, etc.

Darwin’s Theory of Evolution

2. Variation

Differences occur within a species (due to: sexual reproduction, mutations, selective breeding, or genetic engineering).

Darwin’s Theory of Evolution

Causes of Variation:

Sexual reproduction – combining genes of 2 parents

Mutations- sudden change in a gene

Darwin’s Theory of Evolution

Causes of Variation:

Genetic engineering – replacing certain genes or sections of DNA

Selective breeding- choosing organisms with desirable traits to reproduce

Darwin’s Theory of Evolution

3. Adaptation

Individuals with helpful variations survive and reproduce better than those without.

Darwin’s Theory of Evolution

4. Speciation

Over time, organisms that have adapted make up a population and become their own species.

Darwin’s Theory of EvolutionDarwin’s Theory of Evolution

Extinction- the death of all organisms in a species may occur when not adapted to environment