lecture 2

10 inference 3 the unequal ability of individuals to

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Unformatted text preview: r reading Malthus. •  Observation #4: Members of a population vary extensively in their characteristics –  No two individuals are exactly alike Figure 22.9 15 9/30/12 •  Observation #5: Much of this variation is heritable –  Experiments in plant and animal breeding prove this. •  Inference #2: Survival may depend in part on inherited traits Terminal Lateral buds bud Brussels sprouts Cabbage Flower cluster Leaves Cauliflower Kale Flower and stems Broccoli –  Individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals Stem Wild mustard Kohlrabi Figure 22.10 •  Inference #3: The unequal ability of individuals to survive and reproduce –  Will lead to a gradual change in a population, with favorable characteristics accumulating over generations •  This is the process called Natural Selection –  All that is required for this process is heritable (that is, genetic) variation that affects fitness Summary of Natural Selection •  Natural selection is differential success in reproduction –  That results from the interaction between individuals that vary in heritable traits and their environment 16 9/30/12 •  Natural selection can produce adaptations of organisms to their environment (a) A flower man8d in Malaysia (b) A s8ck man8d in Africa Figure 22.11 •  If an environment changes over time –  Natural selection may result in adaptation to these new conditions Natural Selection in Action •  Two examples –  Darwin s Finches –  HIV 17 9/30/12 A case study: Natural Selection Darwin s Medium Ground Finch •  Seed eater living on Daphne Major Island •  Drought in 1977 caused 84% mortality •  Only large hard seeds remained for food Evolution by Natural Selection •  Requires heritable variation that affects fitness •  Predicts:...
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