DARWIN & NATURAL SELECTION Unit #1 - Evolution

The First Scientists  Aristotle  Species are fixed and unchanging  Carolus Linnaeus  Species’ resemblence shows pattern of creation NOT evolutions

Fossils & Paleontology  Fossils – remains or traces of organisms from the past  Cuvier  Advocate of catastrophism  Catastrophism – each boundary b/w strata represents a catastrohe that destroyed many species living at the time

Gradualism  Hutton  Gradualism – profound change can take place through the cumulative effect of slow but continuous processes  Lyell  Uniformitarianism – the same geological processes are operating today as in the past

Lamarck’s Theory of Evolution  Lamarck  Use and disuse  Inheritance of acquired characteristics

Charles Darwin Figure 22.3 England EUROPE NORTH AMERICA Galápagos Islands Darwin in 1840, after his return SOUTH AMERICA Cape of Good Hope Cape Horn Tierra del Fuego AFRICA HMS Beagle in port AUSTRALIA Tasmania New Zealand PACIFIC OCEAN Andes ATLANTIC OCEAN

Darwin’s Finches Figure 22.4 a–c (a) Cactus eater. The long, sharp beak of the cactus ground finch (Geospiza scandens) helps it tear and eat cactus flowers and pulp. (c) Seed eater. The large ground finch (Geospiza magnirostris) has a large beak adapted for cracking seeds that fall from plants to the ground. ( b) Insect eater. The green warbler finch (Certhidea olivacea) uses its narrow, pointed beak to grasp insects.

Descent with Modification Hyracoidea (Hyraxes) Sirenia (Manatees and relatives) Years ago Millions of years ago Deinotherium Mammut Stegodon Mammuthus Platybelodon Barytherium Moeritherium Elephas maximus (Asia) Loxodonta africana (Africa) Loxodonta cyclotis (Africa)

Ernst Mayr  Evolutionary biologist Ernst Mayr  Has dissected the logic of Darwin’s theory into three inferences based on five observations

Inference #1  Inference #1 – Production of more individuals than the environment can support leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving each generation

Inference #2  Survival depends in part on inherited traits. Individuals whose inherited traits give them a high probability of surviving and reproducing in a given environment have higher fitness and are likely to leave more offspring than less fit individuals

Inference #3  This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over generations

The Origin of Species  Two major points:  Presented evidence that the current species are descendents of ancestral, different species  Natural selection is the mechanism for evolution

Natural Selection at Work  Antibiotic resistant bacteria  Insecticide resistance

Artificial Selection Figure 22.6 Terminal bud Lateral buds Brussels sprouts Cabbage Flower cluster Leaves Cauliflower Flower and stems Broccoli Wild mustard Kohlrabi Stem Kale

Evidence: Homologous Structures  Why would these be evidence for evolution? Figure 22.9 HumanCat Whale Bat

Vestigial Structures

Evidence: Analogous Structures  Why would these be evidence for evolution?

Evidence: DNA and Amino Acids Figure Species Human Rhesus monkey Mouse Chicken Frog Lamprey 14% 54% 69% 87% 95% 100% Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide

Evidence: Embryology

Evidence: Camouflage

Evidence: Mimicry