evolution review

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!!!