11 1 Genetic Variation Within Population KEY CONCEPT

11. 1 Genetic Variation Within Population KEY CONCEPT A population shares a common gene pool.

11. 1 Genetic Variation Within Population SPECIES- group of organisms so similar that they can breed to produce fertile offspring POPULATION- a group of the same species living in an area where no two individuals are exactly alike due to variations that have led the fittest individuals to survive and pass on these traits ALLELE- An allele is an alternative form of a gene. Organisms typically have two alleles for a single trait, one being inherited from each parent. ALLELE FREQUENCY- measure of how common an allele is in a population GENE POOL- all of the alleles of all species in a population

11. 1 Genetic Variation Within Population Genetic variation in a population increases the chance that some individuals will survive. • Phenotype-a trait produced by 1 or more genes which provides variation in the gene pool. v. Examples: body size- tall or thin; feather patterns- ruffled or smooth • Genetic variation leads to phenotype variation. • Phenotype variation is necessary for natural selection. • Genetic variation is stored in a population’s gene pool. – Gene pool is made up of alleles in a population – New allele combinations form when organisms have offspring

11. 1 Genetic Variation Within Population • Allele frequencies measure genetic variation. – measures how common allele is in population – can be calculated for each allele in gene pool

11. 1 Genetic Variation Within Population Genetic variation comes from several sources. • Mutation is a random change in the DNA of a gene. – can form new allele – can be passed on to offspring if in reproductive cells • Recombination forms new combinations of alleles. – usually occurs during meiosis – parents’ alleles arranged in new ways in gametes

11. 1 Genetic Variation Within Population Genetic variation comes from several sources. • Hybridization is the crossing of two different species. – occurs when individuals can’t find mate of own species – topic of current scientific research