Bio 1A_ Lecture 6.pdf - Bio 1A Illustration of Darwin's 3rd and 4th observations-variation in trait is-Reproductive differences DDT Resistance EXAMPLE

Bio 1A_ Lecture 6.pdf - Bio 1A Illustration of Darwin's 3rd...

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Bio 1A October 16, 2018 Illustration of Darwin's 3rd and 4th observations. -variation in trait is -Reproductive differences DDT Resistance EXAMPLE Evolution DDT resistance by insect pests. DDT ineffective cause individuals can now survive over time. It happens all the time. Galapagos Finch example: Change in beak depth of Galapagos finches They measured their beaks based on how the year was dry or wet. Some Details on the GALAPAGOS FINCH STUDY-1 Good science:long-term study began in 1973- Peter & Rosemary Grand & students Médium ground finch on Daphne Major Feed on small tender seeds when smaller ones hard to find Lean times: few of either kind of seed available SOME DETAILS ON THE GALAPAGOS FINCH STUDY-2 FINDINGS: 1. IN DRY YEARS WHEN HARD SEEDS AVAILABLE, BEAK SIZE increases 2. When many seeds available , smaller beak size increases 3. Dramatic dry year:population drops from 1200 to 200- mostly females survive What do they do? Choose males with larger beaks.
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  • Fall '15
  • RichardSymanski

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