EvolutionEvolution…It’s only a theory!

Who??Who??

Charles Darwin is the naturalist who is most associated with the theory of evolution.

Darwin was aboard the ship the Beagle when it made a journey around the globe

His most noted visit was to the Galapagos Islands off the coast of South America

Who??Who??

While on the Beagle, Darwin made and recorded various observations on the species he saw.

He published his findings and thoughts in 1859 when he wrote On the Origin of Species by Means of Natural Selection.

What is it??What is it??

What it is….What it is….

Evolution is the change in a population over time through the process of natural selection.

Natural selection is commonly referred to as “survival of the fittest”

What it is….What it is….

In a population there is genetic variation (example brown and green beetles)

Because of factors that influence reproduction (ex. Disease, predation, camouflage, etc.) some individuals have a greater chance at reproduction = passing genes onto the next generation

What it is….What it is….

As a result, the more advantageous traits get passed on more often and become more numerous in the population.

Over time the changes in the population lead to a new species

REMEMBER!! A species is a group of interbreeding organisms.

Visual

What it is not…What it is not…

It is NOT “Lamarckism”◦Lamarckism is based on the idea that the

environment causes changes in an organism◦Example: Trees get taller so giraffes stretch

their necks. Each following generations have longer necks.

Only genetic traits are transferred to the next generation. Environmental factors may influence the reproductive success of individuals and their traits.

What it is not….What it is not….

Evidence for EvolutionEvidence for Evolution

Fossil Record◦The fossil record shows the existence of simpler

life forms and documents the age of the earth (= enough time for evolution to occur)

◦Downfall is that the fossil record is incomplete because not every species is fossilized.

DNA and Proteins◦Scientists can now study the similarities

between the DNA of two different species◦Similar DNA sequences mean similar proteins

(Remember!! DNA RNA Protein Trait)

Evidence for EvolutionEvidence for Evolution

Homologous Structures◦The forelimbs of vertebrates (arms, fins, wings,

etc.) have the same bones which indicates a common ancestor.

ExamplesExamples

Peppered moth simulation◦Example: In a soot-covered forest, dark colored

moths have an advantage over light colored moths because they are harder for predators to see. Since more of them survive predation, they are able to reproduce and pass their traits on to their offspring. Over time the dark moth population rises above the light colored moths.

EvolutionEvolution

PRACTICE!!!◦Work in pairs to complete the worksheet.