E VOLUTION “It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change.” ~Charles Darwin

E VOLUTION Change in a species’ genetic makeup over time Theory Theory (well tested explanation) Charles Darwin

B EFORE D ARWIN … Inheritance of Acquired Traits (Jean Baptiste Lamarck) Organisms acquired or lost traits based on use during its lifetime & passed to offspring

B EAGLE (1831) Collected specimens & fossils around the world

GALAPAGOS ISLANDS Observed many organisms High number of endemic species (species found only there) 97% of island is protectedisland

G ALAPAGOS ISLAND SPECIES OF INTEREST

1859 – ORIGIN OF SPECIES Before DNA Introduced Artificial selection Natural selection Evolution

ARTIFICIAL SELECTION Nature provides variation, humans select variations that are useful. Examples: Farmers breeding best livestock Domesticated dogs

NATURAL SELECTION The traits that help an organism survive in a particular environment are “selected” for in nature

STEPS IN NATURAL SELECTION 1. Genetic variation Difference in color, size, etc. Genetic mutation (after Darwin) 2. Over population 3. Struggle to survive Not enough resources 4. Successful reproduction Well adapted live and reproduce

Adaptation Video

EUROPEAN PEPPERED MOTHS Rested on tree trunks Moths rest with their wings folded down Birds were predators

E UROPEAN P EPPERED M OTHS Two color variations Dark Pale Before 1850 Pale more common By 1860 Dark more common

W HAT HAPPENED IN THE 1850 S ? Trees covered in lichens Pale: blended Dark: stood out 1850s – Industry Soot covered trees Dark: blended Pale: stood out Simulation

N ATURAL S ELECTION TO E VOLUTION Insecticides – chemicals used to rid plants of unwanted insects Antibiotics – treat bacterial infections Work well before = now ineffective Why? Resistance

SUMMARY OF DARWIN’S THEORY 1. Organisms differ; variation is inherited 2. Organisms produce more offspring than survive 3. Organisms compete for resources 4. Organisms with advantages survive to pass those advantages to their children 5. Species alive today are descended with modifications from common ancestors

T WO T YPES OF EVOLUTION 1. Divergent – related species become more dissimilar 2. Convergent – unrelated species become more similar in appearance as they adapt to a similar environment

E VIDENCE OF E VOLUTION Fossil Record Homologous structures DNA Embryonic structures

Youngest Oldest F OSSIL R ECORD Fossils changed between different layers of the earth

HOMOLOGOUS STRUCTURES Structures with different mature forms that develop from the same embryonic tissue Modified for specific function

ANALOGOUS STRUCTURES Similar form & function, but are structurally quite different Same habitat

DNA Common ancestors =common DNA Greater # of DNA similarities = closely related

EMBRYONIC STRUCTURES Embryos may look more similar to adults All vertebrates look similar as embryos embryos

VESTIGIAL STRUCTURES Remnants of once useful structures Ex. – WhaleWhale Hind limb bones Ex. – Humans Goosebumps

Speciation Changes leading to formation of new species. Populations evolve and become reproductively isolated reproductively isolated from reproductively isolated each other(members of two populations cannot interbreed) Behavioral isolation Behavioral isolation Geographic Isolation