What is Evolution? Evolution is the progressive change in organisms or species over time.

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

Early Scientists… n 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 n This theory was proven false!!!

According to LaMarck…

Then came Charles Darwin Born 1809 Studied at Edinburgh and Cambridge 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 ‘The Origin of Species’ was published Died 1882 Darwin’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 Darwin was interested in natural history and made careful observations while on his voyage Did not recognize significance until back in England, 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 Darwin Developed ‘Theory of Natural Selection’ based on his observations from the Beagle voyage of 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 Darwin and 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 Evolution n Extinction- the death of all organisms in a species may occur when not adapted to environment