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UNIT 4 - Evolution. Today ’ s agenda : Notes on natural selection Tomorrow and Thursday: study guide Friday: open ended questions. I can construct an explanation based on evidence for how natural selection leads to adaptation of populations. IMPORTANT DATES.
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UNIT 4 - Evolution Today’s agenda: Notes on natural selection Tomorrow and Thursday: study guide Friday: open ended questions I can construct an explanation based on evidence for how natural selection leads to adaptation of populations
IMPORTANT DATES • JUNE 11: FINAL (OPEN-ENDED QUESTIONS) all periods • JUNE 12: I won’t be on campus • JUNE 13: FINAL (MULTIPLE CHOICE) Periods 6 and 5 • JUNE 14: FINAL (MULTIPLE CHOICE) Periods 1 and 2 • JUNE 15: FINAL (MULTIPLE CHOICE) Periods 3 and 4
Evolution https://www.youtube.com/watch?v=Ci9jfMvoLb4
How the different shape of these birds’ beaks affect these organisms?
Adaptation • An adaptation is a characteristic that enhances the survival AND reproduction of organisms that bear it. • How did the lab demonstrate the concept of adaptation?
Environmental Competition: Individuals compete (or fight) with other members of their species for food, mates and resources- NOT all members of a population can survive!
Differential reproduction: Individuals that are more adapted to their environment will eat more, survive, and have more babies.
Why did the color of peppered moths change over the years? https://www.youtube.com/watch?v=etsjB-6u-6w
Genetic Variation: Difference between individuals of the same species. Their phenotypes are different. All species have genetic variation
Genetic variation can come from 2 places 1. Sexual reproduction- parents pass different traits to their offspring 2. Mutations- random Changes in DNA
Natural selection Natural selection: mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals. The environment (nature) is the selective agent
Think-Pair Share What acts as a selective pressure on a population?
Think-Pair Share What acts as a selective pressure on a population? • Competition for food • Competition for a mate • Changes in the environment • Predators • Parasites
How do we know natural selection can change a population? • we can recreate a similar process through artificial selection! • Artificial selection: “evolution by human selection” “descendants” of the wolf
Think • Imagine you spray an environment with insecticide. The environment is insects free for a few days, then the environment gets infested and the situation is worse than before. • What might have happened?
Unexpected consequences of artificial selection Pesticide resistance Antibiotic resistance
Insecticide resistance • Spray the field, but… • insecticide didn’t kill all individuals • variation • resistant survivors reproduce • resistance is inherited • insecticide becomes less & less effective
Natural Selection https://www.youtube.com/watch?v=0SCjhI86grU http://www.youtube.com/watch?v=ZPDwyjzRBJ0
You do • What is genetic variation? • Give an example of genetic variation • What are the two places genetic variation comes from? • What is an adaptation? • Give an example of an adaptation • What adaptation might help a cheetah survive? • Why can’t all members of a population survive?
Rock Pocket Mice https://www.youtube.com/watch?v=sjeSEngKGrg
Check for understanding Based on your new acquired knowledge, natural selection acts on • the genotype • the phenotype • both
White board According to artificial selection, who selects? • The environment • Humans • Animals • Scientists • God
White board According to the theory of natural selection, who selects? • The environment • Humans • Nature • Scientists • God
White board The development by scientists of a new color in a rose is the result of 1. natural selection 2. artificial selection 3. descent with modification 4. overproduction