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Transcript of Evolution
pg. 170-197 Evolution Key Words and phrases Some more definitions . Paleozoic --> Mesozoic---> Cenozoic Geological Time Scale cause:
Overpopulation-more offspring produced than can survive
Variations- Members of the same species differ
Competition- Offspring compete for survival
Selection- some variations make individuals better fit for survival
Environmental Change- changes in the environment can affect an individual's survival
Genes- help determine survival is passed from parent to offspring Cause and Effect Fossils Diversity Finches What important observations did Darwin make on his voyage?
What hypothesis did Darwin make to explain the differences between similar species?
How does natural selection lead to evolution?
variation A species is a group of similar organisms that can mate with each other and produce fertile offspring A fossil is the preserved remains or traces of an organism that lived in the past. Darwin was puzzled by some of the fossils he observed. For example, he saw fossil bones that resembled the bones of living sloths Beginning of earth --------------------> Present Approx. 4.6 billion years ago First animal appears 600 million years ago Paleozoic Era Darwin's Observations Diversity
Characteristics /Instincts Brazil- insects that looked like flowers
Argentina- sloths "There are more than 1.7 million species of organisms on earth" Darwin hypothesized: A small number of animals/plants came to the Galapagos islands from the mainland
Might have been blown out to sea by a storm or adrift on a log(s).
Offspring reproduced differently thanthe same species on the mainland. Birds appeared to be different on the Galapagos Islands than those on the mainland, but showed similarities or common traits. Comparisons Mainland Galapagos Isl. Iguanas Tortoise Finch small claws to climb trees where they ate leaves Large claws to grip slippery rocks to eat seaweed Dome shaped and saddle-shaped shells Different shaped beaks adapted to what they had to eat Evolution Scientific Theory Darwin theorized: "different conditions meant that species gradually changed over many generations" "Well-tested concept explaining a wide range of observations" Selective Breeding "Repetition in breeding pure-traits in animals" Example:
Horses Natural Selection Darwin's Book: "The Origin of the Species" "process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species." Natural Selection continued.... Overproduction: Insects producing too many offspring and not enough:-
Living Space Variations "Any difference in traits between individuals of the same species" For Example, in Insects:
able to eat foods that are members of their species cannot
Color difference in same species
Competition: Selection: Environmental Change: Direct / Indirect conflict Helpful traits passed on through generations
Gradual accumulation of favorable traits Change in environment forces survival