lecture 2 - father sometimes the two alleles are the...

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I. The evolution of starvation resistance II. What is evolution? III.What is natural selection? What if …you only let the “best” flies reproduce? (top 20% of starvation resistance) selecting for starvation resistance. After one generation, hours until death increased by 1 hr (from 20 hrs to 21 hours) after 10 generations, 28 hrs until death. After 60 generations of selection, 160 hours. Take home message #1: species are not immutable. We can watch them change in nature or even cause them to change A related experiment? What if we cut off mice tails and only breed those mice After 60 generations will the mice be born with no tail? No! Why are anti-bacterial soaps dangerous? What is evolution? A gradual process in which something changes into a different and usually more complex or better form… A change in allele frequencies within a population Some important terminology Gene: section of dna instructing how to produce a trait Allele: one variant of a gene (several may exist) We each carry two copies of every gene (one from our mother, one from our
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Unformatted text preview: father) sometimes the two alleles are the same (BB or bb) sometimes they are different (Bb) We can measure the frequency of “B” and “b” Take home message #2: evolution is a change in allele frequencies within a population Charles Darwin Unexpected patterns Darwin observed 1. finch variation 2. similarity between fossils of extinct species and the living species in an area “struggle for existence--? Organisms better suited to an environment have a greater prob. Of surviving the struggle and will leave mor4e offspring. Through evolution, orgs. May become better matched with their environment Natural selection occurs if there is: Variation Heritable Differential reproductive success .q: why is “survival of the fittest” a misnomer what is adaptation? A feature *that helps you live and reproduce better) A process *by which organisms become better able to live and reproduce in their environment )...
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lecture 2 - father sometimes the two alleles are the...

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