Evolution Study Guide
Definitions: Write the definition and understand key concepts related to the following vocabulary
· Adaptation A characteristic that improves an individual’s ability to survive and reproduce in a specific environment. Can be physical or behavioral
· Natural Selection Process where more “fit” individuals are able to survive and reproduce
· Fossils Remains of an organism, commonly found in sedimentary rocks
· Fossil Record A history of life shown by fossils found in layers of the earth’s crust
· Ancestor An organism from which another has descended
· Trait A characteristic passed down from one generation to the next
· Evolution Process where characteristics in a population change over time causing a new species to possibly arise
· Vestigial Structures A structure in a species that has no useful purpose (In humans, wisdom teeth, tail bone, appendix)
· Homologous Structures Structures of organisms that are the similar but serve different functions (Remember the human arm compared to other organisms)
· Charles Darwin Naturalist who studied evolution. He was known for studying the beaks of finches and iguanas on the Galapagos Islands
· Cast Fossil An imprint of an organism typically found in sedimentary rock
· Mold Fossil An imprint of an organism that was filled in with other sediments
Key Ideas:
1. Explain the four parts of natural selection.
a. Overproduction: Making more offspring than will survive allowing the best to make it to adulthood
b. Inherited variation: Offspring have different combinations of traits so those with the best combinations will reproduce
c. Struggle to survive: Must be able to obtain food, find shelter, and avoid predators. Those that do will pass on the traits that enabled them to survive
d. Successful reproduction: Those best adapted to the environment will produce offspring more likely to survive
2. How does speciation occur? Explain each part of the process.
a. Separation: A species is split by a geographic (allopatric) barrier, behavioral differences, or different mating seasons (temporal).
b. Adaptation: 2 groups change over time to fit into their environments
c. Division: After a long time the groups will no longer be able to interbreed (2 separate species)
3. Explain the case study on whales. How does this relate to the theory of evolution?
The theory is that whales evolved from land mammals. This is shown through linking fossils back to a land based mammal. Whales also have a hip bone and hind limb bone (vestigial structure) from their ancestors. Whales are also mammals, which links them to their ancestors as opposed to fish with gills.
4. Explain each era of the geologic time scale from oldest to youngest. Include key events and organisms for each.
a. Precambrian: Oldest era, this is the time when the earth was forming. There were originally no organisms. This time had lots of volcano eruptions and violent storms. Single-celled organisms developed from simple chemicals. Cyanobacteria began to produce oxygen for the atmosphere as they went through photosynthesis
b. Paleozoic (early life): Era known for its aquatic organisms. There was a lot of marine life until the end when the largest mass extinction on earth occurred killing almost all of the marine life.
c. Mesozoic (middle life): Era known as the age of the reptiles. This was the time of the dinosaurs. The most well know theory for the end of this era was a meteorite that hit earth destroying most organisms.
d. Cenozoic (recent life): This is the current era. It is known as the age of the mammals. As the dinosaurs began to die out the mammals began to become the dominant type of organisms.
5. Identify the four key pieces of evidence that support the theory of evolution. Make sure to explain key concepts associated with each component.
a. Anatomical structures: Homologous structures: Organisms that share a common ancestor has similar features that have been modified to their environments. Ex: Forelimbs of humans, cats, bats, and whales
b. Genetics: Organisms that share a recent common ancestor have more genes similar to one another. Humans have most of their genome in common with chimpanzees but much less in common with fruit flies. All organisms share the same genetic code.
c. Embryology: The study of animal embryos show that most animals begin looking almost identical. Those less closely related change rapidly, while those closely related (mammals for example) don’t diverge until later.
d. Fossil Record: We can trace changes in species over time by comparing older fossils to newer fossils found throughout earth.
6. AC ONLY: Explain the differences between convergent and divergent evolution. Give examples of each process.
Convergent evolution: When organisms have similar structures but are not evolutionarily linked. These structures are called analogous structures. They share functional similarities due to their environment. An example would be insect wings compared to bird wings.
Divergent evolution: When organisms look similar with adaptations to their specific environment because they have evolved from a founder species. These are called homologous structures. An example would be Darwin’s finches.