evolution review do now: turn in cladogram labs from yesterday
TRANSCRIPT
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!!!