Topic 17: Variation and selection Flashcards
What is variation?
Variation is the differences between individuals of the same species.
What is continuous variation?
Continuous variation results in a range of phenotypes between two extremes, such as body length or mass.
What is discontinuous variation?
Discontinuous variation results in a limited number of phenotypes with no intermediates, such as ABO blood groups.
What causes continuous variation?
Continuous variation is caused by both genetic and environmental factors.
What causes discontinuous variation?
Discontinuous variation is usually caused by genes.
What is mutation?
Mutation is a genetic change in the base sequence of DNA.
How do mutations contribute to genetic variation?
Mutations introduce new alleles into a population, contributing to genetic variation.
What factors increase the rate of mutation?
Ionising radiation and some chemicals can increase the rate of mutation.
What is natural selection?
Natural selection is the process by which organisms with advantageous traits are more likely to survive, reproduce, and pass those traits on to the next generation.
What are the stages of natural selection?
(a) Genetic variation within populations
(b) Production of many offspring
(c) Struggle for survival, including competition for resources
(d) Better-adapted individuals have a greater chance of reproduction
(e) These individuals pass on their alleles to the next generation
What is an example of natural selection in action?
The development of antibiotic-resistant bacteria is an example of natural selection.
What is adaptation in the context of natural selection?
Adaptation is the process by which populations become better suited to their environment through natural selection over many generations.
How is selective breeding carried out?
Selective breeding involves (a) selecting individuals with desirable features, (b) crossing them to produce the next generation, and (c) selecting offspring that show the desirable features.
What are some examples of artificial selection?
Examples include breeding cows for increased milk production, wheat for easier grain separation, and dogs for specific physical characteristics.
What are adaptive features?
Adaptive features are inherited traits that help an organism survive and reproduce in its environment.
