B17- Variation and Selection Flashcards
(19 cards)
Define Variation
Differences between individuals of the same species
Define Genetic Variation
Difference in genotype (alleles present in an organism)
Phenotypic variation
differences in phenotype (characteristics displayed)
Phenotype=
Genotype + effects of the environment
Define Mutation
genetic change
What do mutations cause?
New alleles are formed as the sequence of SNA results in different proteins being coded for
Causes of variation [2]
- Genetic
- Environment
Types of variation [2]
- Continuous
- Discontinuous
Define Continuous Variation [4]
individuals in a population have a range of (intermediates) phenotypes between two extremes
- data quantitive
- No distinct categories
- Histograms
Define Discontinuous variation [4]
2 or more distinct categories
- no intermediates
- individual falls into one of these categories
- Bar charts
What causes continuous variation?
- Several genes + environment
What causes discontinuous variation
- Genes only
Define artificial selection (selective breeding)
Choosing particular organisms with desirable characteristics to breed together and continuing this over many generations.
How is artificial selection carried out? [5]
- individuals with desirable characteristics are manually chosen
- Breed them together
- Select offspring with desirable characteristics
- Breed them together
- Repeat this over many generations
Define Natural Selection
A process in which individuals with advantageous features are more likely to survive + reproduce and pass on their alleles to the next generation.
What are the 5 stages of Natural Selection [10]
- Variation- different alleles
- Overproduction- more offspring than the environment can support
- Struggle for existence- competitions for resources
- Survival of the fittest- best adapted individuals survive (favorable alleles survive and reproduce)
- Advantageous alleles are passed on- more favorable alleles in the population
Agent of selection
Natural - Nature
Artificial - Humans
Species chance of survival
Natural- Good (increases)
Artificial- Low (decreases)
Speed of Change
Natural- Slower
Artificial- Faster
