20 Patterns of Inheritance Flashcards
What is the gene pool?
The total sum of all the genes in a population at any given time is known as the gene pool.
What is the allele frequency?
The relative frequency of a particular allele in a population is the allele frequency.
What does the Hardy-Weinberg principle state?
“In a stable population with no disturbing factors, the allele frequencies will remain constant from one generation to the next, and there will be no evolution”
What is the Hardy-Weinberg principle expressed at?
p2+2pq+q2=1
What factors affect evolution?
- Mutation
- Sexual selection
- Gene flow (movement of alleles between populations)= immigration and emigration
- Genetic drift
- Natural selection
What is stabilising selection?
Stabilising selection is when individuals with alleles for average/normal characteristics are more likely to survive and reproduce.
When does directional selection occur?
Directional selection occurs when there’s a change in the environment and individuals with extreme phenotypes are more likely to survive and reproduce.
What is directional selection?
Natural selection that favours one extreme phenotype.
What is disruptive selection?
Natural selection that favours both extremes of a given phenotype.
What is codominance?
Co-dominance occurs when two different alleles occur for a gene- both of which are equally dominant.
What is autosomal linkage?
Genes present on the same, non-sex chromosome.
What is epistasis?
Epistasis is the effect of one gene on the expression of another gene.
What is the founder effect?
When a few individuals of a species colonise a new area
What is speciation?
Speciation is the formation of new species through the process of evolution.
What is allopatric speciation?
Speciation that occurs as a result of a physical barrier (e.g river or sea) between populations- they are geographically isolated
What occurs as a result of allopatric speciation?
- The environments of the different groups will often be different and so will the selection pressures resulting in different physical adaptations
- This leads to genetic drift
What is sympatric speciation?
Speciation that occurs when there is no physical barrier between populations.
When does sympatric speciation occur?
- Members of two different species interbreed and form fertile offspring
- The hybrid formed, which is a new species, will have a different number of chromosomes to either parent and may no longer be able to interbreed with members of either parent population.
- This stops gene flow and reproductively isolates the hybrid organisms.
What is a polymorphic allele?
A gene with more than two possible alleles.
What is artificial selection/selective breeding?
Selection of individuals for breeding with desirable characteristics.
