Chapter 17 Notes - Evolution of Populations

genetic change

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.