Monday, September 17, 2007

Sexual Selection

Hey 8th period AP biology class members. Today we discussed many things in continuation on the topic of evolution and natural selection. We started off going over the lion mane slide. The key point Mrs. Foglia was showing with that slide was that animals do not choose a mate because they know that they have better genes, but because they are just attracted to that member of the opposite sex. If it happens to be that the member of the opposite sex has good genes, then it's great, but that is not what animals are actually looking for.

Also during class today we discussed phenotypes and genotypes. Phenotype is the physical appearance, anatomy, while genotype is the genetic make-up of an organism. The genotype controls the phenotype of an organism.

We also discussed how alleles (genotype) determine the color or physical appearance (phenotype) in the power point on straw fish. In the example, two blue alleles means the fish would be blue, two yellow alleles means the fish would be yellow, and one blue allele and one yellow allele means the fish would be green. The powerpoint on the straw fish shows how natural selection is based on the phenotype which changes the frequency of alleles. With the example given during class, the predator ate most of the yellow fish because they did not blend in easily, natural selection, which affected the allele frequency because with the yellow fish gone there are less yellow alleles. Remember, even though the frequency may change, in this case yellow decreased and blue increased, the total remains the same.

Tomorrow's sherpa will be Shana Lunney.

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