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genetic change
Interbreeding permits any ________ that occurs to spread throughout populations of a species.
Genetic Drift
________: In small populations, chance alone can cause a change in the allele frequency in a population.
20th century geneticists
________ discovered that heritable traits are controlled by genes and carried on chromosomes- changes in genes and chromosomes generate variation.
Natural selection
________ works directly on phenotype, not genotype.
Darwin
________ based his evolutionary theory on heritable variation, but he had no idea where the variation came from or how heredity worked.
Mutations
________- can introduce new alleles into the gene pool, changing allele frequencies and causing evolution to occur.
allele frequencies
Founder effect- when ________ change because of the migration of a small number of individuals in a population.
Sexual reproduction
________ is a major source of genetic variation.
number of phenotypes
The ________ produced for a given trait depends on how many genes control the trait.
Hardy
________- Weinberg Principle: allele frequencies in a population will remain constant unless one ore more factors cause those frequencies to change.
Segregation
________- separation of alleles during meiosis.
separate species
Speciation- when populations become reproductively isolated, they may evolve into two ________.
Fitness
________- the ability to survive and reproduce.
Alleles
________- specific forms of genes- may vary from individual to individual.
Darwins Finches
________- natural selection shaped the bird beaks on each island depending on the food source.
Species
________- a population or a group of populations whose members interbreed and produce fertile offspring.
Genetic equilibrium
________- the situation in which allele frequencies remain constant.
Population
________- a group of individuals of the same species that mate and produce offspring.
new population
Speciation in the Galapagos finches occurred by founding of a(n) ________, geographic isolation, changes in the ________ gene pool, reproductive isolation, and ecological competition.
genetic terms
In ________, evolution is any change in the frequency of alleles in a population over time.
Small population size
________- genetic drink affects small populations.
Gene flow
________ from immigration or emigration- changes in allele frequency can be produced by gene flow.
Behavior Isolation
________: two populations have differences in courtship rituals or other reproductive strategies that involve behavior.
Geographic Isolation
________: two populations are separated by geographic barriers such as rivers and mountains.
Temporal Isolation
________: reproduction occurs at different times of the year.
Independent Assortment
________- genes for different traits assort independently.
Natural selection
________- if different genotypes have different fitness, ________ will disrupt genetic equilibrium and evolution will occur.
Mutation
________: any change in a sequence of DNA.
Natural selection
________ on single- gene traits can lead to changes in allele frequencies and thus to evolution.
Natural selection
________ never acts on a single gene- it acts on an entire organism because the whole organism either survives to reproduce or dies before reproducing- populations evolve over time, not single individuals.
natural selection
Inherited variation can lead to ________ because it can result in differential reproductive success for individuals with different phenotypes.
