EVOLUTION REVIEW

Do Now: Turn in cladogram labs from yesterday

Part I: Phillosophy of Truth

What is science? Observable, measurable quantities only! Hypotheses require mechanisms (how) with

supporting evidence Truth and Logic in Science

Negative proof is impossible (Russell’s Teapot, Flying Spaghetti Monster)

Occam’s Razor: the least complex solution to a problem has the highest probability of being correct

Parsimony: measure of complexity. More parsimonious = simpiler.

Part II: Evolution Basics

Evolution: how species change over time.

Natural selection: the mechanism of evolution. the process by which heritable traits that

make it more likely for an organism to survive and successfully reproduce become more common in a population over successive generations.

Natural Selection

For natural selection to function, there are 3 requirements Variation Differential mortality heritability

1: Variation For natural selection to work, there must

be a range of characteristics in a population.

2: Differential Mortality

Some characteristics or variations allow an organism to survive and/or reproduce more than others.

3: Heritability

The characteristics that lead to increased survival and reproduction must be able to be passed on to subsequent generations

Types of Evolution

Speciation: The evolution of new species from pre-existing ones

Two types of speciation Phyletic speciation: One species replaces

an older one (think fossils) Divergent speciation: One species evolves

into two new species.

Phyletic vs. Divergent Speciation

2 Modes of Evolution

Gradual Evolution: small changes over long periods of time

Punctuated Equilibrium: big changes in short time periods.

Gradualism vs. Punctuated Equilibrium

Fossils

Fossil: preserved remains or traces of an ancient organism.

Most are formed by mineralization (turning to rock)

Trace fossil: not the organisms itself, but from an organism (dung, footprints, etc.)

Other fossils: amber, ice, tar

Fossil Geology

Sedimentary rock: rocks made of compressed layers of sediment. Only type of rocks that contain fossils

Fossil Geology

Law of Superposition: Older rocks are found below newer ones, since layers of sediment are deposited over time.

Darwin

Charles Darwin proposed the theory of evolution by natural selection in his 1859 book The Origin of Species.

His evidence came from an expedition around South America on the H.M.S. Beagle.

Most important to his work are the unique creatures of the Galapagos Islands

Representing Change

Phylogram (aka cladogram): A diagram representing evolutionary relationships.

Homologous Structures

Homologous structures are similar in form and composition in different species.

Phylogeny

Phylogeny is the relatedness among different species (note: phylogenetic tree shows phylogeny)

It is based on: Fossil evidence Homology (including genetics)

That’s Evolution Part 1!

BIG quiz tomorrow – study this guide!!!