Chapters 15, 16, & 17 Test Review

Darwin read books of Charles Lyell and James Hutton on his voyage on the HMS Beagle. James Hutton was a scientists who attempted to explain how rock layers form and change over time. When a farmer breeds his or her best livestock, they are using artificial selection. Charles Darwin called the ability of a species to survive and reproduce fitness. In humans, the pelvis and femur, or thigh bone, are involved in walking. In whales, the pelvis and femur are vestigial organs.

The Appendix (Vestigial)

All members of a population are the same species All members of a population are the same species. The two main sources of variation are gene shuffling and mutations. The separation of populations by barriers such as rivers, mountains, or bodies of water is called geographic isolation. A factor that is necessary for the formation of a new species is reproductive isolation. The Galapagos finch population is a good example of speciation.

Although they often live in the same habitat, the American toad breeds earlier in the spring than the Fowler’s toad does. What can be inferred from this information? The two species do not interbreed because of temporal isolation.

Examples of fossils include preserved Eggs Body parts Footprints Sedimentary rock is formed from small particles of sand, silt, and clay. What proportion of all species that have ever lived has become extinct? More than 99 percent. Most fossils form in sedimentary rock.

How many half-lives have passed if a fossil has one eighth of its original amount of carbon-14? Three half-lives have passed.

Darwin’s theory of evolution would suggest that more offspring are produced than can possibly survive. A process of change in species over time best defines evolution by natural selection.

Charles Darwin observed that instead of being perfect and unchanging, individuals in a species show variation or different traits. Certain animal structures that have different functions in different species and develop from the same embryonic tissues are called homologous structures.

In which case would carbon-14 be more useful for radioactive dating: For wooden beams, in native American cave dwellings, which are probably less than 7000 years old, or for the fossil of an early mammal that is probably 100,000 years old? Carbon-14 would be better at dating the younger fossil. If used to date the older fossil, the remaining fraction of carbon-14 left in that fossil would be very small and would be difficult to measure precisely.

Graph A: The average beak size of birds has increased due to directional selection. There are now no birds with the smallest beaks, and some birds with very large beaks have evolved.

Graph B: When individuals with an average form of a trait have the highest fitness, the result is stabilizing selection. There are more birds with an average body mass, and no birds with extremely large or small body mass.

Graph C: Disruptive selection has occurred. There are more birds with smaller or larger beak sizes, and fewer or no birds with average beak size.

Directional Selection The average beak size of birds has increased due to directional selection. There are now no birds with the smallest beaks, and some birds with very large beaks have evolved.

When individuals with an average form of a trait have the highest fitness, the result is stabilizing selection. There are more birds with an average body mass, and no birds with extremely large or small body mass.

Disruptive selection has occurred. There are more birds with smaller or larger beak sizes, and fewer or no birds with average beak size.