Introduction to Evolution Tree of Life All species

Introduction to Evolution

Tree of Life • All species are related • All species share a common ancestor • Evolution…is how the tree of life gets bigger!

Fixed Species Hypothesis • All species had always been the same, and would never change (Aristotle, 2000 years ago)

1800 s – Fossils are Discovered

Transmutation Hypothesis (1800 s) • Jean Baptiste de Lamarck • Acquired traits could be passed down to offspring

Charles Darwin • 1831 -1836: world voyage on HMS Beagle

Natural Selection • “Survival of the Fittest” – only the best adapted individuals survived to pass their genes to offspring • Over time, a population’s traits can change

Gregor Mendel • Basic principles of genetics – how characteristics were passed down to offspring • How organisms could change from one generation to the next

Putting it all together • Genetic mutations = changes in organisms • Environmental changes = changes in organisms • How? Natural Selection (Darwin)

What is a scientific theory? Hypothesis -suggested explanation -uncertain -limited data -educated guess / idea Theory -supported explanation -lots of certainty -lots of data & test -general belief Evolution is THE major theory that underlies the field of biology!

A theory can be wrong • How? If new evidence disproves it

I can… • Explain the Fixed Species hypothesis • Explain Lamarck’s Transmutation hypothesis • Explain Darwin’s and Mendel’s contributions to the Theory of Evolution • Explain the difference between a scientific hypothesis and a scientific theory