What is evolution? Where can we see examples of it? Evolution = process of biological change where descendants end up different than their ancestors

Charles Darwin played a big part in understanding of evolution Was an English naturalist Joined the crew of the H.M.S. Beagle on a 5 year trip Made many new observations & collected lots of fossils

Some of Darwin’s key observations: There was variation of traits among similar species Species from 1 island looked different from nearby islands Which islands? Species must be adapted to their environment  Ex. Galapagos tortoises  change in neck length/shell shape  Ex. Finch beak size

Fossils shows changes in species over time Fossils also showed Earth changed Some of Darwin’s key observations (continued):

Created a classification system to group organisms Darwin wasn’t the first to think about evolution  he was influenced by many 1. Carolus Linnaeus: mid 1700’s / Swedish 2. Erasmus Darwin: mid 1700’s / English Suggested all living things descended from a common ancestor

Suggested all organisms evolved towards perfection 3. Jean-Baptiste Lamarck: early 1800’s/ French Changes in environment caused changes in traits/behaviors Use or disuse of organs affected size These acquired traits could be passed on to offspring

Earth has changed because of slow, continual changes 4. James Hutton/Charles Lyle: geologists Geological processes that shape Earth have stayed the same Earth is millions, if not billions, of years old Hutton Lyle

Suggested that resources were natural limits to human population growth 5. Thomas Malthus – early 1800’s/English economist Darwin reasoned this applied to other plants and animals even more  they have more offspring

Organisms were usually bred for specific traits  artificial selection 6. Farmers & Breeders Humans were the selective agent, not nature Not all traits selected by humans would help the organism survive Selected traits had to be heritable

Independently developed a theory similar to Darwin’s 6. Alfred Wallace – mid 1800’s/English Both were based on natural selection  individuals with beneficial adaptations survive better and produce more offspring The environment is the selective agent

Darwin published his ideas in his book: On the Origin of Species 4 main principles to the theory of natural selection 1. Variation – difference are the basis of natural selection 2. Overproduction – lots of offspring = competition

3. Adaptation – those adapted to their environment survive better 4. Decent with modification – since those with adaptations survive better, they pass those traits on

Every good theory needs evidence, so what was Darwin’s? Darwin’s Evidence: Fossils Geography – where organisms were & weren’t found Embryology – young versions of some organisms showed similarities Anatomy – comparing body parts

Homologous structures = features similar in structure, but different in function (starts the same, ends different)

Analogous structures = features similar in function, but different in origin (starts different, ends the same) Environmental factor play a large role

Vestigial structures = remnants or organs that had a function in an early ancestor Usually reduced in size since they’re not needed Ex: Whale’s pelvis Ostrich wings Wisdom teeth