Selection Flashcards
Define individuals in relation to selection:
unit of selection where they survive and reproduce or they don’t
Complete the sentence:
New alleles are continuously created at a rate (µ) by…
mutation
What are new mutations initially?
- Rare
- Most are recessive
Complete the sentence:
When rare, recessive alleles are mostly present in heterozygotes, …
which makes selection against them negligible
Do rare alleles disappear or persist?
Persist
Complete the sentence:
Dominant alleles are always expressed and so if they are frequent,…
selection against them will remove recessive alleles
What contributes to allele loss or gain in relation to mutation?
Genetic drift
What is genetic drift?
The chance difference in transmission of alleles, leading to fluctuations in allele frequency
What doe genetic drift affect?
- Strong affect on rare alleles
- Greater influence on rare alleles than selection
- Primary mechanism for increasing rare recessive alleles
- Responsible for changing frequency of neutral mutation
What has a greater influence on rare alleles selection or genetic drift?
Genetic drift
What is called when genetic drift in small populations can produce biased frequencies?
Founder effect
Are genetic bottleneck and genetic drift similar ideas?
Yes
What is balancing selection?
Variation is maintained in population
What effects balancing selection?
- Heterozygote advantage
- Frequency dependent selection
- Fluctuating selection
Finish the sentence:
Alleles only have an advantage when…
Rare
What is heterogeneous environment in relation to selection?
Different phenotypes are favoured in different sub-areas of the population
What are the two components of fitness?
- Survivorship
- Fecundity
What is fitness?
Measure reproductive success
-the reproductive success of a genotype relative to the optimum genotype.
What is the equation for fitness?
W = 1 - s
What does W stand for in the fitness equation?
Fitness
What does s stand for in the fitness equation?
Selection ( reduction in success of genotype
What does s determine in the fitness equation?
How fast allele frequency’s change
What is another name for fitness landscape?
Adaptive landscape
What is adaptive landscape?
Used to visualize the relationship between genotypes (or phenotypes) and reproductive success
Finish the sentence:
Since the environment change the adaptive peaks…
shift
What drives evolutionary change?
Selection
What are the modes of selection on quantitative traits?
- Stabilising selection
- Directional selection
- Disruptive selection
What is stabilising selection?
Type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value
What is directional selection?
Occurs most often under environmental changes and when populations migrate to new areas with different environmental pressures
What is another name for disruptive selection?
Diversifying selection
What is disruptive selection?
Changes in population genetics in which extreme values for a trait are favoured over intermediate values
- Forms two distinct groups
- Driving forces behind sympatric speciation
What is sexual selection?
selection acts on an organism’s ability to obtain or successfully copulate with a mate.
What is the problem with sexual selection?
Can produce features which are harmful to an individuals survival
What is kin selection?
Changes in gene frequency across generations driven by interactions between related individuals
What is relatedness measures?
The coefficient of relatedness.
What is relatedness measures equation?
r = (1/2)^n
What is the Hamilton’s Rule?
the definition of fitness as the number of an individual’s alleles in the next generation.
What does Hamilton’s rule lead to?
Inclusive fitness
What is inclusive fitness?
an individual’s combined representation in the gene pool of the next generation
What is the equation of the Hamilton’s Rule?
(Cost of not reproducing/benefit of helping kin selection) < relatedness
