Evolution Questions Darwinian Snails

DARWINIAN SNAILS Di ko sure sa answers :)) Q1. If there is NO VARIATION in shell thickness within a population of snails, and no mutations occur, what happens to shell thickness in response to crab predation? (Hint: Recall your experiment in the second exercise, when you turned variation off.) ● ● ● ● All snails in the population grow thicker shells. Some snails in the population evolve thicker shells. The average shell thickness evolves to be much thicker over several generations. There is no change in shell thickness within the population. Q2. If there is NO SELECTIVE SURVIVAL based on shell thickness within a population of snails, what happens to shell thickness in response to crab predation? (Hint: Recall your experiment in the second exercise when you turned off selective survival and snails were eaten randomly.) ● ● ● ● The average shell thickness increases within each generation, but there is no change in shell thickness from generation to generation. There is evolution by natural selection of shell thickness, and average shell thickness increases every generation. There may be evolution of shell thickness, but not through natural selection and not necessarily toward thicker shells. There is no change in shell thickness within the population. Q3. If mutations arise that affect shell thickness within a snail population, then with crabs present, those mutations: ● ● ● ● Will result in offspring always having thicker shells than their parents. Will result in offspring having either thicker or thinner shells than their parents. Will happen because the parents choose to give them to their offspring. Will occur because crabs are present and snails need protection against predation. Q4. The 14 species of finches on the Galapagos Islands evolved from a single species that migrated to the islands several million years ago. Different finch species live on different islands. A major difference among finch species is in their beaks: both size and shape vary greatly. Assume that a population of one of these finch species is undergoing evolution by natural selection with respect to beak size and shape. What changes occur gradually over time that indicate the population is evolving? ● ● ● ● Within their lifetimes, some individual finches' beaks change in size or shape. The proportions of finches having different beak sizes/shapes change across generations. Each finch's learned ability to use its beak is automatically passed on to its offspring. All finches in each new generation develop the same new, improved beak size and shape. Q5. Could individuals of a species look different today than individuals of the same species did many generations ago? Why or why not? ● ● ● ● Yes, all individuals can change a little and pass those changes on to their offspring. Yes, some individuals can change a little and pass those changes on to their offspring. Yes, some individuals with certain traits are more likely to survive and pass those traits on to their offspring. No, species do not change even after many generations, so individuals of the same species would not look different. Q6. Which of the following is REQUIRED for the process of evolution by natural selection to occur? ● ● ● ● Numerous species in the same region must have recently become extinct. A food source must disappear. There must be a sudden environmental change. Traits must be inherited from one generation to the next. Q7. DDT is an insecticide that was used extensively in the mid-1900s to kill mosquitoes. It was very effective at first, but after a few decades DDT became less effective at killing mosquitoes because many populations had evolved resistance to DDT. Which of the following conditions would biologists say was required for the evolution of DDT resistance in a population? ● ● ● ● A few mosquitoes in the population were resistant to DDT before it was ever used. Mosquitoes in the population learned to adapt to the high levels of DDT in the environment. The mosquito population needed to evolve DDT resistance in order to avoid extinction. Exposure to DDT caused specific, nonrandom mutations for DDT resistance within the population. Q9. Consider the following hypothetical scenario: An ancestral species of duck had a varied diet that included aquatic plants and terrestrial plants and insects. These ducks spent time on both land and water. Individuals of this species varied in the amount of webbing in their feet, with some individuals having more webbing and some having less. As many years went by, the environment changed such that the aquatic food sources were much more plentiful than those on land. Many generations later, almost all ducks had more webbing on their feet. How is this best explained? ● ● Use the following passage to answer the next two questions. Ducks are aquatic birds. Their feet are webbed and this trait makes them fast swimmers. Biologists believe that ducks evolved from land birds that did not have webbed feet. The amount of webbing on a duck's feet is a heritable trait. ● ● Q8. While webbed feet were evolving in ancestral ducks, with each generation: ● ● ● ● Most ducks had about the same amount of webbing on their feet as their parents. Most ducks had more webbing on their feet than their parents. Most ducks had less webbing on their feet than their parents. The amount of webbing on ducks' feet had no relationship with the amount their parents had. Ducks with less webbing worked harder than ducks with more webbing to eat aquatic plants. The more they used their feet, the more webbed their feet became, so they got enough food to survive and reproduce. Due to chance mutations, all the ducks' feet in the next generation had more webbing. They were therefore able to eat aquatic plants and get enough food to survive and reproduce. Ducks with more webbing were better at eating aquatic plants than ducks with less webbing, so the ducks with more webbing survived and reproduced better than ducks with less webbing. Ducks with less webbing needed to grow more webbing in their feet in order to improve their access to aquatic plants, which allowed them to survive better and reproduce more. Q10. Horned lizards use their horns to defend against predatory birds. A researcher observed that lizards living in areas with predatory birds have longer horns than those in areas with no predatory birds. This observation led her to hypothesize that longer horns offer more protection against predation than do shorter horns. To test this hypothesis, the researcher tagged 20 lizards with long horns and 20 lizards with short horns in each of two locations: Desert Valley, where there are no predatory birds, and Cactus Corner, where there are predatory birds. She returned every week for 12 weeks to measure survival of tagged lizards. The graphs below represent her findings. GENETIC DRIFT AND BOTTLENECKED FERRETS Q1. What is the founder effect? ● ● ● ● Sampling error that occurs during the establishment of a new population by a small number of migrants. Strong natural selection acting on the founders of a new population because the environment they are now living in is so different from the environment they came from. A phenomenon named after William Founder, who observed that top predators generally have low genetic diversity. Rapid population growth following a bottleneck. What can you conclude from the researcher's results? Q2. The effects of genetic drift are more pronounced in smaller populations. ● ● ● ● ● ● The hypothesis that longer horns offer greater protection against predation is supported. The hypothesis that longer horns offer greater protection against predation is NOT supported. The experiment is well designed, but the results are inconclusive about the hypothesis. The experiment is not well designed to test the hypothesis. True False Q3. Inbreeding tends to decrease the proportion of homozygous individuals in a population (i.e., individuals with two copies of the same allele). ● ● True False Q4. The effective size of a population is: ● ● ● ● The size of an idealized randomly-mating population that is not under selection and has the same heterozygosity as the actual population. The size of an idealized randomly-mating population that has the same heterozygosity as the actual population, but does not lose heterozygosity over time. The size of an idealized randomly-mating population losing homozygosity at the same rate as the actual population. The size of an idealized randomly-mating population losing heterozygosity at the same rate as the actual population. Q5. Which of the following tends to reduce the effective size of a population? Check all that apply: ● ● ● Increasing the census population size An unbalanced sex ratio Non-random mating Q6. If gametes from a gene pool combine randomly to make only a small number of zygotes, the allele frequencies among the zygotes may be different than they were in the gene pool because: ● ● ● ● The effects of natural selection are more pronounced in small populations. The effects of genetic drift over several generations are more pronounced with small numbers of gametes. The effects of differences in frequencies for different alleles are more pronounced with small numbers of zygotes. The effects of sampling error are more pronounced with small samples. Q7. Genetic drift is different from natural selection because: ● ● ● ● In natural selection allele frequencies change because some alleles confer higher fitness, whereas in genetic drift allele frequencies change because of chance sampling error. Natural selection acts primarily in large populations, whereas genetic drift acts primarily in small ones. Natural selection is a mechanism of evolution, whereas genetic drift is an outcome of evolution. Natural selection tends to cause rapid evolution, whereas genetic drift tends to cause slow evolution. Q8. Imagine a population evolving by genetic drift in which the frequency of allele K is 0.2. What is the probability that at some point in the future allele K will drift to a frequency of 1? ● 0.2 Q9. A dwindling population of 1000 frogs occupies an isolated watershed in Costa Rica. To help preserve the species, scientists caught 20 frogs to start a new population in a nearby watershed. This species has a gene that affects eye shape. The 1000-member wild population has two alleles for this gene: R and r, with frequencies 0.7 and 0.3, respectively. What will be the allele frequencies of R and r in the 20-member founder population? ● ● ● ● The frequencies will be 0.7 for R and 0.3 for r. The frequencies will be 1.0 for R and 0 for r. The expected frequencies are 0.7 for R and 0.3 for r. The actual frequencies could be different. The founder populations's allele frequencies will necessarily be different than the source population's frequencies. Q10. For a population containing 80 females and 20 males, what is the effective population size, Ne ? ● 0.64