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Explore the impact of selective pressures on phenotypic distribution using simulation. Test hypotheses on coloration, mating, and predation in guppy populations. Understand modes of natural selection through practical analysis.
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1929 – Trofim Lysenko • Head of Soviet Ministry of Agriculture • Strong advocate of Lamarckian Evolution (acquired characteristics) • Attempted to vernalize wheat by freezing prior to germination
DifferentialReproduction • The driving force behind evolution • Populations shift because not all members of the population have the same fitness • Nature provides selective pressures that determine who reproduces most
SelectivePressure • Nature “selects” for various phenotypes based upon whether or not the features of the organism increase its differential reproduction
Modes of Natural Selection • Stabilizing: Favors average phenotypes • Directional: one phenotypic extreme favored • Disruptive: Both extreme phenotypes are favored
Directional Selection & Industrial Melanism (Kettlewell Moth Experiment)
Trinidadian Guppy Analysis • Purpose: To see how the selective pressures of coloration and predation affect the phenotypic distribution in a population • Hypotheses to Be Tested: • Bright coloration leads to preferential mating, causing the population to shift towards bright. • Bright coloration leads to increased predation, leading to a phenotypic shift towards drab
Procedure • To access simulation, google “Sex and the Single Guppy” • There are nine (9) combinations of predator and prey to test. • Each simulation should be run for 100 weeks. Stop manually at this point • BEFORE looking at analysis of results, record the phenotypic results, pop. size and # of Generations