Understanding Evolution: Genetic Variation and Natural Selection

1. Biology I Chapters 16

2. Do Now The diagram above shows several fossilized remains that were discovered at an archaeological dig site. The molecular and structural similarities observed among these organisms is best explained by which of the following? A. human impact B. natural selection C. binary fission D. genetic mutations

3. Which of the following is true about natural selection? • A. Natural selection acts upon individual organisms by changing their genetic code through a process known as gene flow. • B. Natural selection causes changes in populations because of the differential reproductive success of genetically varied individuals. • C. Natural selection causes changes in individual organisms because individuals adapt during their lifetime to better suit their environment. • D. Natural selection acts upon asexually reproducing populations that lack genetic variation among individual organisms.

4. In their first attempts to genetically engineer a cow that will make and secrete human growth hormones in milk, scientists found that they could insert the growth hormone gene into an embryonic calf. When the calf matures, it produces the hormone. However, they discovered that the altered gene gets lost from the genome during meiosis. • What is the best explanation of what will happen in a population of genetically altered cows? • A. The cows will not reproduce because only females will reproduce the altered gene. • B. The cows will not reproduce because neither males nor females will reproduce the altered gene. • C. The cows will reproduce, but neither males nor females will reproduce the altered gene. • D. The cows will reproduce, but only males will reproduce the altered gene.

5. Variation of Traits within a Population Population-a group of the same species living in the same place at the same time. Microevolution-a change in the collective genetic material of a population. Bell Curve-shows the phenotypic variety in a population

6. Phenotype Frequency Phenotype Frequency-The number of individuals with a particular phenotype divided by the total number of individuals in the population

7. Evolution Conditions that can cause evolution to take place: Genetic Drift Nonrandom Mating Migration Mutation-spontaneous allele changes

8. Gene Flow Gene Flow-the movement of alleles into or out of a population due to migration Immigration-the movement of individuals into a population Emigration-the movement of individuals out of a population.

9. Genetic Drift Genetic Drift-The phenomenon by which allele frequency in a population change as a result of random events, or chance

10. Genetic Drift Bottleneck Effect-A type of genetic drift resulting from the reduction of a population, typically by a natural disaster, so that the surviving population is no longer genetically representative of the original population.

11. Genetic Drift Founder Effect-the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population

12. Nonrandom Mating Sexual Selection-the tendency for females to choose the males they mate with based on certain traits.

13. Sexual Selection Sexual Psychology Intrasexual selection-secondary sex structures may be used to compete with members of the same sex for mate. Intersexual selection-mate choice-individuals of one sex (usually females) are choosy in selecting their mates.

14. Stabilizing Selection Stabilizing selection-individuals with the average form of a trait have the highest fitness

15. Disruptive Selection Disruptive Selection-The type of selection that may eliminate intermediate phenotypes

16. Directional Selection Directional Selection-A change in the frequency of a particular gene in one direction in a population Crash Course-Natural Selection

18. Do Now • In the living world, there is a great deal of genetic variation. The genetic information of dogs differs from the genetic information of cats; the genetic information of plants differs from the genetic information of bacteria; your genetic information differs from your father's genetic information; and so on. • Which of the following is least likely to be a source of genetic variation among living organisms? • A. meiosis • B. sexual reproduction • C. mutations • D. asexual reproduction

19. Which of the following processes would be most effective in changing the frequency of certain traits in a population over time? • A. natural selection • B. genetic recombination • C. spontaneous mutations • D. chemically-induced mutations

20. A mutation exists in a gene that controls hair growth on the middle digit of human fingers. Some people have mid-digital hair, while others do not. The gene can be passed from one generation to the next. Which explanation best predicts what should happen to this trait over time? • A. The incidence of mid-digital hair will decrease in the population because it has a selective disadvantage. • B. The incidence of mid-digital hair will increase because it offers no selective advantage. • C. The incidence of mid-digital hair will increase in the human population because it offers a selective advantage. • D. The incidence of mid-digital hair will not change because it offers no selective advantage or disadvantage.

21. Speciation Speciation-the process of species formation. Morphology-the internal and external structure and appearance of an organism.

22. Speciation New species of organisms may emerge if new traits resulting from altered genes are naturally selected. Without genetic diversity, natural selection cannot occur. Evolution does not always progress in one set direction.

23. Isolation & Speciation Geographic isolation-the physical separation of members of a population Allopatric Speciation-occurs when new species arise as a result of geographic isolation

24. Isolation & Speciation Reproductive isolation-results from barriers to successful breeding between population groups in the same area Sympatric Speciation-occurs when two subpopulations become reproductively isolated within the same geographic area

25. Isolation & Speciation Prezygotic barriers-Prevent mating or fertilization between species Temporal isolation-Two species breed at different times Behavioral isolation-There is little or no sexual attraction between species, due to specific behaviors Mechanical isolation-female and male sex organs or gametes are not compatible

26. Isolation & Speciation Postzygotic barriers-operate after hybrid zygotes are formed Hybrid sterility-where hybrid offspring between two species are sterile and therefore cannot mate

27. Rates of Speciation Gradualism-The hypothesis that evolution occurs at a slow, constant rate Punctuated Equilibrium-The hypothesis that evolution occurs at an irregular rate through geologic time Crash Course-Speciation

28. Do Now • In 2 lines, explain the difference between gradualism and punctuated equilibrium.

29. Vocab #1-5 • Bacterium • Ear • Enzyme • Hear • Self

30. Vocab #6-10 • Arm • Depth • Good • Sprout • Weight

31. Vocab #11-15 & Bonus • Homeostasis • Hydrogen bond • Ionic • Polar covalent • Nonpolar covalent • Nonpolar covalent • Specific heat