1. What is antibiotic resistance?How are bacteria able to survive when exposed to antibiotics? 2. During rainy years on the Galapagos Islands, small seeds became abundant. Only birds with small beaks can eat small seeds effectively. If the rain persists for several years, what do you expect to occur due to natural selection? Explain. 3. Two hypotheses that predict why some beetles survive applications of an insecticide are illustrated in the diagram below.Hypothesis 1 says that in a population of beetles,some beetles exist that are resistant to an insecticide. These individuals go on to reproduce generations of beetles that are resistant to the insecticide. Hypothesis 2 says that individual beetles develop mutation that protects them from the insecticide. These individuals go on to reproduce generations of beetles that are resistant to the insecticide. Which hypothesis is correct? Explain your answer. 4. Many organisms found in tidal pools along the west coast of Vancouver Island look almost identical to organisms found in tidal pools along the east coast of New Brunswick. Would you expect these species to be closely related? Explain your answer. 5. Identify each of the following as one of the five mechanisms that cause evolution in populations. Mechanisms can be used more than once. a. Organisms become adapted to their environment. b. The lack of genetic variability among cheetahs has been attributed to this. c. This often results in two adjacent populations having similar genetic variation due to immigration and emigration. d. The movement of humans all over the world can influence this. e. The original finches that were blown over to the Galapagos Islands from South America are an example of this. 6. What is Gene flow?How can gene flow change the allele frequency in a population of species? Give an example. 7. What is Genetic Drift?How can genetic drift change the allele frequency in a large vs.small population? 8. What is the difference between founder effect and bottleneck effect? Give an example for each. 9. Define the following terms with respect to Natural Selection: Stabilizing, Directional,Disruptive ( sketch a graph for each) 10. What is Speciation? Explain and describe the different pre-zygotic and post-zygotic reproductive isolating mechanisms. 11. A true cactus in Africa looks surprisingly like a distantly related euphorbia plant in a desert in Australia. Explain why this might have occurred. 12. What allows for allopatric speciation to occur?Give an example of where this has taken place. 13. You are studying two closely related monkey species in the tropical rainforest . They are not known to interbreed in nature. One species feeds and mates in the treetops of fruit trees.The other species feeds and mates in fruit trees as well.In captivity, these two species interbreed and produce viable, fertile hybrids Hypothesize what type of reproductive barrier could be keeping these species apart in nature. 14. Only about 8500 French settlers colonized the St. Lawrence River valley in Québec between 1608 and 1759. About six million people live there today. Some rare mutations have been identified in the population One is an autosomal recessive mutation affecting hearing and vision. How can you explain these rare mutations in the population? 15. A tan-coloured insect lives in a sandy area.Some insects in the population show some green in their coloration. The climate begins to cool and become moister. Slowly, the habitat is covered by green plants. Use Darwin's theory of evolution by natural selection to explain how the insect population might evolve to be green.

1. **Antibiotic resistance** is the ability of bacteria to survive and multiply in the presence of antibiotics that would normally kill them or inhibit their growth. Bacteria can survive antibiotic exposure through several mechanisms:<br /><br /> * **Enzyme production:** Some bacteria produce enzymes that break down or modify the antibiotic, rendering it ineffective.<br /> * **Altered cell wall:** Changes in the bacterial cell wall can prevent antibiotics from entering the cell.<br /> * **Efflux pumps:** These pumps actively remove antibiotics from the bacterial cell.<br /> * **Target modification:** The antibiotic's target site within the bacteria can mutate, making the antibiotic less effective or completely ineffective.<br /> * **Genetic transfer:** Resistance genes can be passed between bacteria through various mechanisms, such as conjugation, transformation, and transduction.<br /><br /><br />2. If the rain persists and small seeds become the primary food source, natural selection will favor birds with smaller beaks. Birds with smaller beaks will be more efficient at eating the abundant small seeds, giving them a survival and reproductive advantage. Over time, the average beak size in the population will decrease as birds with smaller beaks become more common and birds with larger beaks struggle to find sufficient food. This is an example of directional selection.<br /><br />3. Hypothesis 1 is correct. Antibiotic resistance arises from pre-existing genetic variation within a population. Some individuals already possess genes that confer resistance, and these individuals are more likely to survive and reproduce when exposed to the antibiotic. Hypothesis 2 suggests that mutations arise *in response* to the insecticide, which is incorrect. Mutations are random events that occur independently of the selective pressure.<br /><br />4. While the organisms may look similar due to convergent evolution (adapting to similar environments), they are not necessarily closely related. Geographic isolation prevents gene flow between the populations, allowing them to evolve independently. Genetic analysis would be needed to determine their evolutionary relationship.<br /><br />5. a. Natural Selection<br /> b. Genetic Drift (Bottleneck Effect)<br /> c. Gene Flow<br /> d. Gene Flow<br /> e. Founder Effect<br /><br />6. **Gene flow** is the transfer of genetic material (alleles) between populations of the same species. It occurs through migration and interbreeding. Gene flow can introduce new alleles into a population, increasing genetic diversity, or it can change the frequency of existing alleles, making populations more genetically similar. For example, if wind carries pollen from a population of red flowers to a population of white flowers, the frequency of alleles for red flower color will increase in the white flower population.<br /><br />7. **Genetic drift** is the random fluctuation of allele frequencies within a population due to chance events. In small populations, genetic drift can have a significant impact, leading to the loss of some alleles and the fixation (reaching 100% frequency) of others. In large populations, the effects of genetic drift are less pronounced because random fluctuations are less likely to dramatically alter allele frequencies.<br /><br />8. * **Founder effect:** Occurs when a small group of individuals establishes a new population, carrying only a subset of the genetic variation from the original population. Example: A few individuals from a mainland population colonize an island, and the island population has a different allele frequency than the mainland population.<br /> * **Bottleneck effect:** Occurs when a population undergoes a drastic reduction in size due to a catastrophic event (e.g., natural disaster, disease outbreak). The surviving individuals may not represent the original population's genetic diversity. Example: A wildfire wipes out a large portion of a squirrel population, and the surviving squirrels have a reduced genetic diversity.<br /><br />9. * **Stabilizing selection:** Favors intermediate phenotypes and selects against extreme phenotypes. (Bell curve narrows)<br /> * **Directional selection:** Favors one extreme phenotype, shifting the average phenotype in that direction. (Bell curve shifts to one side)<br /> * **Disruptive selection:** Favors both extreme phenotypes and selects against intermediate phenotypes. (Bell curve develops two peaks)<br /><br />10. **Speciation** is the evolutionary process by which new biological species arise. Reproductive isolating mechanisms prevent gene flow between populations, leading to divergence and eventually speciation.<br /><br /> * **Pre-zygotic barriers:** Prevent mating or fertilization. Examples: habitat isolation, temporal isolation (breeding at different times), behavioral isolation (different courtship rituals), mechanical isolation (incompatible reproductive structures), gametic isolation (incompatible gametes).<br /> * **Post-zygotic barriers:** Occur after fertilization. Examples: reduced hybrid viability (hybrid offspring are weak or don't survive), reduced hybrid fertility (hybrid offspring are sterile), hybrid breakdown (second-generation hybrids are infertile or weak).<br /><br />11. The cactus and euphorbia plant have evolved similar adaptations (e.g., succulent stems, spines) to cope with similar desert environments. This is an example of convergent evolution, where unrelated species evolve similar traits due to similar selective pressures.<br /><br />12. Allopatric speciation occurs when populations are geographically isolated, preventing gene flow. This isolation allows the populations to evolve independently, accumulating genetic differences that eventually lead to reproductive isolation. Example: The formation of the Grand Canyon separated squirrel populations on either side, leading to the evolution of distinct species.<br /><br />13. A likely reproductive barrier is behavioral isolation. Although they can interbreed in captivity, their different feeding and mating locations in the wild may prevent them from encountering each other and mating under natural conditions.<br /><br />14. The rare mutations likely arose in the founding population of French settlers and became more common in the Québec population due to the founder effect and subsequent genetic drift. The small founding population had limited genetic diversity, and random fluctuations in allele frequencies (genetic drift) could have increased the frequency of these rare mutations over time.<br /><br />15. As the environment becomes greener, insects with more green coloration will have a selective advantage because they are better camouflaged from predators. These green insects will be more likely to survive and reproduce, passing on their genes for green coloration to their offspring. Over time, the frequency of green coloration in the population will increase, and the insect population will evolve to become predominantly green. This is an example of directional selection.<br />