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Changes Over Time Quiz and Test Study Guide
Darwin’s Theory
Darwin hypothesized that species gradually change over many generations and become better adapted to new situations.
species- a group of organisms with members that reproduce among themselves in their natural environment
evolution- change in the hereditary features of an organism over time
natural selection- 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.
à overproduction- most species produce more offspring than can possibly survive
à variations- an inherited trait that makes an individual different from other members of the same species (ex. eye color)
à competition- food, space, other resources are limited causing direct or indirect competition
à selection- nature “selects” which variations are helpful; unfavorable ones gradually disappear
à environmental change- a change in the environment can affect which organisms survive
à genes and natural selection- variations can result from mutation and shuffling of alleles during meiosis; these genes are passed on from parents to offspring.
adaptation- any variation that makes an organism better suited for its environment (ex. camouflage)
Evidence of Evolution
Fossils, patterns of early development, and similar body structures all provide evidence that organisms have changed over time.
Evidence:
· fossils- By studying fossils, scientists can infer the structures of ancient organisms and compare them to organisms of today.
· similarities in early development- Scientists also make inferences based on evolutionary relationships by comparing the early development of different organisms. (ex. tails and throat slits in opossum, chicken, fish, salamander)
· similarities in body structure- Scientists study similar bones and muscles in different organisms to prove common ancestors. (ex. dolphin flipper, bird wing, dog leg)
· similarities in DNA- Scientists can compare the DNA structure between organisms to infer if they shared a common ancestor. (ex. dogs are more similar to wolves than coyotes)
homologous structure- body parts that are similar in origin or structure ( ex. bat wing, dolphin flipper)
branching tree- a diagram that shows how scientists think different groups of organisms are related
The Fossil Record (not on Quiz- only on Test)
gradualism- the model that describes evolution as a slow change from one species to another
punctuated equilibrium- model that shows rapid evolution that can come about after the mutation of just a few genes