Download 11.1 Genetic Variation Within Population

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.
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 all 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