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!!!