17.1 Genes and Variation
|1. In your own words, explain what the following phrase means: â€œNatural selection acts directly on phenotype, not genotypeâ€||Natural selection is more focused on the characteristics of the animal, not the alleles.|
|2. Explain the relationship between gene pools and allele frequencies.||Gene pools is all the genes in a species, including the alleles. Â Allele frequencies is how many times an allele shows up in a gene pool. Â|
|3. People usually think that mutations are bad, but that isnâ€™t usually the case. Explain what a mutation is, and how common they are.||A mutation is an unexpected change in chromosomes within a cell. Â Since it is any change, it can be good bad or neither. Â It can improve an organism to help it survive, or be a different colour which could be any of them. Â It could make them less noticeable, more noticeable, or stay the same.|
|4. There are lots of forms of genetic recombination. In your own terms, explain what genetic recombination is, and why you think it is important for the fitness of a species.||It is when the gametes of the parents combine to make a new diploid cell. Â The gametes donâ€™t have to be the exact same as the parents since chromosomes move independently. Â Â It is important because to evolve, survive, and live to reproduction, species need to have variation to pick out the strongest of the group.|
|5. i. Compare and contrast single-gene traits and polygenic traits
ii. Without having any information about the genotype, how can you tell whether a trait you are studying is single-gene or polygenic?
17.2 Evolution as Genetic Change in Populations
|1. Explain the following statement in your own words: â€œAn adaptation is any genetic trait that increases an organismâ€™s chance of passing on its allelesâ€||It means that adaptations help species survive and reach the reproductive age.|
|2. Explain how natural selection leads to changes in allele frequencies in single gene traits. Feel free to use an example to explain your answer.||If an adaptation of a single gene trait is successful, then it will become more frequent.|
|3. Explain and give an ORIGINAL example (not from the book) of each of the following:
i. Directional Selection
ii. Stabilizing Selection
iii. Disruptive Selection
|4. When natural selection is not acting on a trait, you might see evidence of genetic drift.
i. What is genetic drift?
ii. Why is it more likely to occur in small populations?
iii. What is the relationship between genetic drift and the bottleneck effect?
|5. How might the founder effect explain some of the variety seen in Darwinâ€™s finches?||IT explains it because when the finches migrated to the islands, the gene pool was a bit different, and it lead to changes in the phenotype.|
|6. What is genetic equilibrium? Why is it unlikely that one might find genetic equilibrium in a wild population?||It is when a species is not changing, and allele frequencies are not changing. Â It is unlikely because the environment is always changing.|
|7. The Hardy-Weinburg principle is a good way to make predictions about allele frequencies at a given moment, but is not beneficial for making predictions about the future in a wild population. Why not?||It does not take into account predation.
17.3 The Process of Speciation
|1. What is speciation? Why is reproductive isolation so important to the process of speciation?||It is when the same species gets seperated, and evolves into its own species different from the original. Â It is important because it wonâ€™t happen without it.|
|2i. Compare and contrast behavioral, geographic and temporal isolation. What do they have in common? How are they different?
ii. The females in a particular species of frog go into estrus (become reproductively receptive) during the third week of April. A mutation occurs where some females begin estrus during the first week of April, and others during the first week of May. Both of these times are better than the third week of April, because they are during times of low predator activity. Therefore, the population begins to develop two separate mating periods, and over time, there are no more frogs in estrus during the third week of April anymore.
What type of isolation is this?
iii. What do you think will happen over time to the species of frogs described above? Be specific
|3. In 3-5 sentences, summarize the current theory of how Darwinâ€™s finches came to populate the Galapagos Islands.||A founding species went to the Galapagos. Â Since there are many different islands, geographic isolation went down, and they phenotype changed, turning into its own species. Â Then, the gene pool for each population became accustomed to the new changed.|
17.4 Molecular Evolution
|1. What is the relationship between molecular clocks and mutations?||Molecular clocks use mutations as a way to tell when species start to grow away from each other.|
|2. A particular protein, McHughin, has a mutation rate of one mutation per 500,000 years. Humans and chimpanzees both produce this protein. When you compare the gene for McHughin, you will find 26 nucleotide differences. According to this molecular clock, how long ago did the common ancestor between humans and chimpanzees exist?||6-7 million years ago.|
|3. How might a duplicate gene lead to a new trait in a species?||New copies of a gene may undergo mutations and adaptations that change the purpose. Â Since it changes, it can change the phenotype to accommodate.|
|4. What is â€œevo-devoâ€? This isnâ€™t a hugely important vocabulary term, but itâ€™s too cool of a word to not include a question about.||It is Â field of study around the EVOlution of embryo DEVelOpment.|
|5. What is a hox gene? Do your best to explain in your own terms. Feel free to use an example||They are a group of related genes that control the bodily plan along the spine of an embryo.Â Â|