BIOL 2200 Lecture Notes - Lecture 6: Ecotype, Genetic Drift, Sympatric Speciation

• School: University of Virginia
• Department: Biology
• Course: BIOL 2200
• Professor: Jessamyn Manson

Document Summary

Balancing selection: both types maintain multiple forms of alleles. Instead of moving towards fixation, this maintains heterozygosity to maintain diversity: heterozygote advantage heterozygotes have greater fitness than either homozygote, therefore both dominant and recessive alleles are maintained, frequency-dependent selection. Fitness depends on how rare or common the phenotype is in the population, not fixed. Constraints of evolution: allele has to be in the population for selection to occur upon it, only build on what was passed down to us by ancestors, laws of physics, thermodynamics and gravity, sources of genetic variation. Mutation ( creation of new allele: environments change. Phenotypic plasticity ability of organism to change its phenotype or behavior based on environment: ex. Lays eggs in spring, when the winds are cold, and orients nest away from wind. Lays eggs in summer when it is hot, and orients nest towards cool breeze. What is a species: biological species concept.