What is the Darwin/Wallace Theory of Evolution?
Natural Selection states 1. All species produce more offspring than can possibly survive. 2. Resources are limited so organisms must compete. 3. Variation exists within a population. 4. Some variation makes individuals more successful in the environment. 5. Those with the best variation will survive and reproduce. Individuals do not evolve. A population is the smallest unit that can evolve. Variation causes evolution. Sources of Variation: 1. Mutation: invents alleles that never before existed in the gene pool. 2. Sexual Reproduction: creates individuals with new combination of alleles. — Crossing over — Independent assortment — Random fertilization 3. Diploidy: allows recessive alleles to be hidden in heterozygous conditions; therefore, cannot be selected against 4. Outbreeding: mating with unrelated partners (increases possibility of mixing different alleles). 5. Balanced Polymorphism : maintaining different phenotypes in a population –Heterozygote advantage –Hybrid Vigor –Freq
