Ch 16: Evolution of Population

1. Ch 16: Evolution of Population Notes #3

2. What makes up a Population? • ANS: Organisms that belong to the same species and live in the same area.

3. Human Population in Alhambra Total Population: 85, 077

4. What is a Species? • ANS: Members of the same population that can interbreed (mate) and have fertile offsprings Ex. Horse + Horse = Pony (same species)

5. What is a Gene Pool? ANS: Total # of genes found in a population at one time and area Ex. Gene pool for field mouse fur B = Black fur; b = brown 36% bb Phenotype 64% Black 36% brown 16% BB Gene pool in Field mouse Population 48% Bb

6. Causes of Genetic Variations in a Population (4 types) • Mutations: Changes in the DNA lead to genetic and physical differences. Ex. Wild-type Fruit Fly vs White-eye fly

7. 2. Gene Shuffling • Mixing of genes during crossing over in Meiosis • Independent Assortment of genes into sex cells (gametes) Ex. BbHH BH bH

8. 3. Genetic Drift • Tragic events that change the future genotype of a small population Ex. Small Population of Green & Brown Beetles exist, then catastrophic event occurs, leaving a limited # of survivors

9. Genetic Drift of a Small Population of Beetles Which colored beetle will dominate the population in the next 10 years? ANS: Brown Why?

10. 4. Gene Flow • It is the migration of genes moving in and out of a population; leads to the intro of new genes Ex. Two separate populations of beetles (Green vs Brown), one brown beetle migrates and introduces new genes to green beetle population

11. Process of Speciation What is Speciation? ANS: Process where new species are formed due to some type of isolation mechanism

12. Isolation Mechanisms Creating New Species Types of Isolation Mechanism • Geographic Isolation: 2 population separated by geographic barriers (rivers, mountains,valleys, large bodies of water) can no longer meet or breed together. Ex. Two population of squirrels separated by a river, evolved and became more different from each other over time

13. Geographic Isolation

14. 2. Reproductive Isolation • Occurs when 2 different species can’t breed and produce fertile offspring

15. What do you get when you mate a horse with a donkey? • A mule. Which is incapable of having its own offspring, b/c the parents are not the SAME species. + = father Sterile Hybrid mother

16. (2 types) • Behavioral Isolation: 2 populations can’t breed or understand each other b/c they have different mating rituals/calls. Ex. 2 population of birds (Pigeons & Crows) can’t mate b/c they sing different mating songs to attract mates

17. b. Temporal Isolation • 2 populations have different mating seasons or feeding times, so they won’t meet and mate with each other. Ex. One species of birds feeds during the morning and the other feeds at night, both won’t be able to meet and mate

18. Natural Selection Affecting Phenotype of a Population

19. Types of Natural Selection on Physical Traits 3 Types of Selection • Directional Selection • Stabilizing Selection • Disruptive Selection

20. Background Information • Moth Survival Rate during the Industrial Revolution • (Black Winged vs. Grey Winged vs White Winged Moths) 1800s Factories built & ashes from burning coal polluted the surrounds

21. Types of Moths Black White Peppered

22. Moths’ Natural Predator Mmmm…I love eating moths!

23. 1) Directional Selection • Natural Selection favors the survival of one extreme phenotype compared to the others • Environment: Entire area covered in black ash • Which type of Moth will have higher fitness (survival)?____________ Black Winged

24. What will the curve look like? Graph below # of Moths In Pop. Population After Selection Original Population White Peppered Black (Moth wing color)

25. 2) Stabilizing Selection • Natural Selection favors the survival of the intermediate/mixed phenotype & against the extreme colored ones • Environment: Snow that is mixed with black ash • Which type of moth will have a higher fitness? ______________ Peppered Winged

26. What will the curve look like? Graph below Selection against extremes # of Moths In Pop. Population After Selection Original Population White Peppered Black (Moth wing color)

27. 3. Disruptive Selection • Natural Selection favors the survival of the two extreme phenotypes and against the intermediate/mixed ones. • Environment: One side of town covered in black ashes and the other covered in snow • Which type of moth(s) will have a higher fitness?________________ Peppered winged

28. What will the curve look like? Graph below Selection against the intermediate # of Moths In Pop. Population After Selection Original Population White Peppered Black (Moth wing color)

29. Question of the day • If a new moth eating bird is introduced to the environment and eats only black winged moths, which Selection will the moth’s population show? • Stabilizing Selection • Disruptive Selection • Directional Selection White winged Which moths will dominate the surrounds? ____________

30. Classwork • Section 16-1, 16-2, 16-3 (Wkbook; Answers ONLY) • Section Assessment (Write down Q’s & A’s_ • 16-1; p. 396; #1-4 • 16-2; p. 402; #1-5 • 16-3; p. 410; #1-4 • Stamps Needed for All work • Make sure to finish Per 2’s Classwork (Section 15-3 Wkbk & Section Assessment 15-3 from Mon)