Unformatted text preview: BIS 2B F09 Study Questions For Lectures 11 and 12 1. Georges Cuvier was one of the many scientists who studied fossils. He observed fossilized marine forms in places that were now mountain tops, found fossils of organisms that no longer existed, and noticed that fossil forms appeared to change from older to younger strata. Which explanation for these observations did he prefer? a) all geological processes that operate now, operated then b) high reproductive rates resulted in limited survival of each type c) a series of great catastrophes occurred in each environment d) organisms evolved in some places and became extinct in others e) continents had moved, altering the distributions of many species 2. Which of the observations below would support the idea that controlling which individuals were permitted to mate could have a large effect on the phenotypes of offspring? a) the naturally-occurring variation within a population b) the results of plant and animal breeding trials c) the similarity between birds on two islands d) the fossil record for shelled animals e) the similarity between parents and offspring 3. True/False: there is much more variation in skull morphology among wild members of False... Wild dogs the canid (dog) family than there is among breeds of domestic dogs. need less types of heads to 4. How would you distinguish artificial selection from natural selection? survive in the wild usually involves humans Randomized 5. To compare rates of evolution in elephants and fruitflies, one should compare populations across: a) years b) the time needed for development c) individual lifetimes d) generation times e) centuries 6. Egyptians first bred cattle thousands of years ago. What did they use to estimate the heritability of particular characters? a) b) c) d) e) the number of offspring produced by each breeding pair the fraction of offspring that survived in each pair the degree of resemblance between parents and offspring the variation in character types within each population the tendency of domesticated animals to breed with wild relatives 7. Goannas are big (6 ft.) lizards that live in Australia. They eat birds, eggs, and small lizards. Some goannas eat toads often and others rarely do. When poisonous toads were introduced into Australia some goannas died, but the population rebounded quickly. Natural selection probably acted on the goanna population; describe the 3 conditions necessary for natural selection to act in this case and explain how each condition would have been important in the goanna example. i) ii) Variation Multiple alleles of the same gene will allow the gene to respond differently to various stresses of environment. Heritability Needed to make variation Only the best will survive iii) Struggle for existence 8. Why is it important to have genetic variation in a population? a) b) c) d) e) to permit a response to natural selection to prevent mutations from occurring to increase the number of offspring that survive to keep the population size high it isn’t important 9. Why was Malthus’s idea of “the struggle for existence” important in the development of Darwin’s theory of natural selection?
Because Darwin knew that species were changing, but he didn't know 10. In why. year was Darwin’s Origin of Species published? what 1859 11. Nature programs sometimes include the statement that natural selection operates for the good of a species. This is incorrect. There is no mechanism for an organism to know it is part of a species. You may have visited the elephant seals at Año Nuevo (just south of San Francisco on the California coast). The seal population is now quite large, but during the late 1800’s hunters reduced the population to a handful of individuals. The current population has very low genetic diversity. The animals also have a mating system where males fight with other males for access to reproductive females. A winning male may mate with up to 30 females; this mating pattern further reduces genetic diversity in the offspring. For the good of the species, any male who wins a fight and gains access to many females should allow other males to mate with these females because it would increase genetic diversity. Suppose this behavior did evolve in one male and that the behavior had a genetic basis. Consider the relative fitness of this male. Use an argument based on fitness to explain what would happen to the genes for this trait in future generations. The gene that codes for "sharing mates" would without a doubt, increase. The relative fitness of the male would decrease because this "sharing mates" male would be more common in future generations and would produce less offspring when compared to the other males around him who share the same gene. Though the gene would increase in frequency, the number of mates a male carrying this gene would likely decrease. Would this behavior persist in a population? Be sure your reasoning is clear. (1 point) Yes, it would for awhile at least until competition for females came again or the gene was eliminated for some reason. 12. The behavior of lovebirds has been well-studied in the lab. When animals are given paper to shred for nesting, Fisher’s lovebirds tear paper into long strips. A different species, the Peach-faced lovebird, tears paper into short strips for nesting. When Peach-faced lovebirds are mated with Fisher’s lovebirds, the hybrid offspring tear intermediate-sized strips of paper. (Note: hybrids are used to refer to offspring produced by mating two different types of organisms). What can we learn from the hybrids? Fisher=Long Peach-face=short a) hybrid offspring have very high fitness b) behavior has a genetic component c) bird species can never cross d) natural selection favors hybrids e) artificial selection cannot operate in lovebirds 13. How could one introduce genetic variation into a population? a) b) c) d) e) bring in mates from distant populations increase the amount of mating increase the number of offspring that survive prevent some males from mating while allowing others multiple females prevent some females from mating while allowing others multiple males 14. How does natural selection result in organisms that seem very well-suited to their environments? Only the best phenotypes will get passed onto the later generations. 15. Does natural selection track the past or prepare for the future? Explain your reasoning.It does not do 16. Suppose you decide to breed mustard plants to get a new, strongly- flavored, mustard for the gourmet market. You sample 1000 wild plants by tasting a few leaves, and find 10 plants that have a unique spicy flavor. The plants will flower soon. Before you go looking for investors in your mustard company, what do you need to show in order to develop a successful breeding program? How will you show it and how will your breeding program proceed? I would isolate the 10 spicy plants and interbreed them with eachother then test the offspring to find out if more spicy plants would be produced. I would want to find out if the allele for spicyness was dominant or recessive (in this case, it appears to be recessive), so I would get a few homozygous dominant plants and then base my breeding system on that. In reality though, I would just clone the 10 original spicy plants and mass produce them.
either. While it does keep some genes of the past, natural selection operates only on the current genes for the current environment. ...
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This note was uploaded on 03/23/2011 for the course BIS 2B taught by Professor Strong during the Spring '08 term at UC Davis.
- Spring '08