Exam 1 Study Guide
Exam 1 Study Guide Bio 425
Popular in Evolution
Popular in Biology
This 7 page Study Guide was uploaded by Jessica Painter on Wednesday February 24, 2016. The Study Guide belongs to Bio 425 at Radford University taught by Dr. Sheehy in Spring 2016. Since its upload, it has received 89 views. For similar materials see Evolution in Biology at Radford University.
Reviews for Exam 1 Study Guide
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 02/24/16
Evolution Exam Study Guide Answer the next three questions based on the following situation: Spade foot toads are desert dwelling toads that emerge after summer rains, mate and lay eggs in ephemeral (temporary) ponds and then burry themselves in the mud till the next rainy season. A population of spade foot toad shows two genetically controlled behavioral phenotypes. Individuals who are MM and MN lay eggs two days the first rains and suffer loss of eggs if the rains do not continue. NN individuals must experience a two weeks of afternoon rains before they lay eggs. 1) During normal years rains are consistent. Once the rains start they will continue for 1 month. Females who are MM or MN lay on average of 600 eggs 15 survive to adulthood. NN individuals lay, on average, 320 eggs of which 9 survive to adulthood. The relative fitness of these 3 genotypes is: a) MM = MN = 0.89, NN = 1.0 b) MM = MN = 90, NN=36 c) MM = MN = 1.0, NN = 0.4 d) MM = MN = 1, NN = 0.6 e) MM = MN = 15, NN = 9 2) In abnormal years rains are sporadic and early egg layers loose many clutches of eggs to dehydration. Here MN and MM individuals lay, on average 540 eggs 3 of which reach adulthood. NN individuals lay, on average, 320 eggs of which 9 survive to adulthood. The relative fitness of these 3 genotypes is: a) MM = MN = 0.20, NN = 1.0 b) MM = MN = 180, NN=36 c) MM = MN = 0.33, NN = 1.0 d) MM = MN = 1, NN = 0.6 e) MM = MN = 9, NN = 3 3) a) Question 5 is selection for a recessive, question 6 is selection for a dominant. b) Both questions 5 and 6 are selection for a recessive c) Question 5 is selection for a dominant question 6 is selection for a recessive. d) Both questions 5 and 6 are selection for a dominant. 4) If a population is small enough to be affected by drift, we can make some predictions about the equilibrium genetic conditions in that population, including that the population a) Will not be well adapted to its environment b) Will resemble local populations because drift causes alleles to be exchanged among populations c) Will be fixed for some alleles, and the probability that an allele is fixed is equal to its mutation rate d) Will have lost some alleles, and the more rare the allele the more likely it is to have been lost e) None of the above 2 Short Answers Please answer with SENTENCES and/or a wellexplained graphic. Answers must be complete and coherent to earn full credit. 5) The trait ‘tailless’ in lab mice is controlled by a dominant allele (TT, Tt tailless mice, while tt normal tails). Developmental studies have shown that TT mice do not develop normally and die during embryogenesis. How much would you expect the frequency of the T allele to decrease after one generation? (You may assume that tailed and tailless mice do equally well in the lab colony you are describing). HINT: You don’t need numbers here. Just show the change algebraically. (5 pts.) If the TT mice do not develop normally and die during embryogenesis, then they have a fitness level of 0. The mice with Tt have tailless mice. If this continues, the frequency of the big T allele will decrease because of the decrease in fitness among TT mice. The mice with the short tails will eventually go away as well, or decrease over time. 6. What four conditions are necessary and sufficient for evolution to occur? (Hint: Chucks postulates). The four Darwin principles that we classify if evolution can occur are: 1. Individual variation (phenotypes vary, ecology and genetics) 2. In every generation, more progeny produced than can survive (population dynamics, ecology) 3. Survival and reproduction of individuals not random Within the current conditions, individuals with some phenotypes produce more offspring, find more mates, survive better (i.e. are more fit) 4. Some phenotypic variants passed on to offspring (heritable information, genetics) 3 7) Many populations of frogs have a small frequency of individuals that express a light stripe down the center of the back. Research in the wild has shown that the stripe has no fitness consequence, and laboratory breeding studies show that the stripe is produced by recessive allele, s (SS, Ss produce the normal patterns, while ss produces a striped frog). 7a) If 9% of frogs exhibit the striped pattern, what are the frequencies of the s and S alleles in the population (5 pts.) The frequency of s allele is 0.09, The frequency of the S allele is 0.91 7b) After 3 generations, what is the frequency of the s allele? (3 pts.) 9/100= ss 91/100=S_ (ss) n+3= 0.000729 (S_) n+3= 0.753571 7c) Assume that these frogs have very specific habitat requirements and habitat loss has reduced their population size to only about 30 breeding individuals. If the population size remains at this size indefinitely, what do you expect to happen to the frequency of striped frogs in the populations (Be specific and explain your answer, giving all the information you can about the trend you describe) (7 pts.) If the stripe allele does not affect the frogs fitness, the phenotype and allele frequency should stay the same. However over time, the allele might increase or decrease depending on environmental changes. 8) One population of frogs occurs in a bog, an environment with acidic water. Another population frogs occur in an environment with basic water. Neither population currently is adapted for acid conditions. In which population do you think a mutation for acid tolerance would be most likely to occur? Why? The population with the mutation for acid tolerance would most likely happen with the population that lives in the acidic water. If there was a mutation that changed the frogs adaptively to acidic water, then the frog will have a higher fitness. 4 9) How could the rate of mutation be an adaptation, evolved through natural selection, even if the specific mutations that occur may or may not be adaptive? The rate of mutation can be an adaptation that has evolved through natural selection through the mutation of different alleles. These alleles could either benefit the organism or not benefit the organism. If the mutated trait benefits the fitness of the organism, then they pass that trait to their offspring. 10) What are the assumptions about a population that must be true for the population to be in HardyWeinberg Equilibrium? For each assumption, describe what happens if the assumption is NOT true of a population, and explain why this result occurs. 1. Random Mating: If random mating is not happening, this is called inbreeding, when this happens it is more common to find homozygosis in all genes 2. No selection: If there is selection, then it eventually leads to the loss of an allele frequency (except for the favored one) 3. Infinite population size: A small population size will change the allele frequencies. 4. No mutations: There can be mutations that will keep alleles in a population, even if there is a strong selection against them 5. No migration: The allele frequencies will become more homogeneous 5 11) The graph below depicts changes in allele frequency due to natural selection at a single locus. Each line represents a different selection regime. Associate the letter of each line with the type of selection. ___E____ Strong selection for a dominant ___D___ Weak selection for a dominant ___C___ Strong selection for a recessive trait ___A___ Weak Selection for a recessive trait ___B____ Selection for a heterozygote. 6 12) A population of frogs varies in size of warts: WW individuals have big warts, Ww individuals have small warts, and ww individuals have smooth skin (no warts). You quantify the number of warts of 100 individuals and find the following numbers of adult, reproducing individuals with each wart condition type: Phenotype: Big Warts: 77 Small Warts: 21 Smooth skin: 2 a. What is the frequency of the w allele in the population? 2^2 x ½ (21) = 42/100 = 0.42 freq(w) Freq W= 0.58 FreqWw= 2(0.58)(0.42)=0.4872 b. Big warted frogs produce the most toxins, Small warted frogs have less toxin and smooth skinned frogs have no toxin. You hypothesize that big warts have the highest fitness because they are produce more toxin and are thus best protected from critters that want to eat them. To test this, conduct a chi squared test to determine whether or not wart size is in Hardy Weinberg proportions at the 5% level of significance. What can you conclude about whether the population is in Hardy Weinberg proportions? Does this conclusion support your hypothesis regarding the fitness of different wart sizes? Genotype Observed Expected X^2 WW 77 33.64 55.88 Ww 21 48.72 12.58 ww 2 17.64 13.86 NOT IN HARDY WEINBERG
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'