Genetic Patterns/Change Flashcards
What is the allele frequency?
Allele frequency is the occurrence of the allele over the total number of alleles.
How do we define/measure genetic change?
Genetic change is when the allele frequency decreases/increases
What is a gene pool?
Gene pool is all the alleles present within the population
What is natural selection?
Some phenotypes / traits / individuals are better suited to the environmental conditions. These individuals survive and reproduce.
Explain how natural selection works?
• Most populations are too large for their environments resources required. • Those who ‘fit’ the environment best, survive and are selected for. • The ones who don’t are selected against/ they are out-competed and die. • Those who are selected for pass down their alleles to the next generation. Thus changing the allele frequency of the population.
What is sexual selection?
Is when the female selects the dominant/favorable male to reproduce with so only the most sexually compatible individuals are selected for.
What is migration?
The movement of individuals from one population to another
What is the difference between immigration and emigration?
Immigration: individuals migrating into a population - Can add new alleles to a population - Increases genetic biodiversity Emigration: individuals leaving a population - Can remove alleles from a population - Reduces genetic biodiversity
Why is migration important for genetic change?
This allows for gene flow between populations
What is genetic drift?
Variation in the frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.
What is the founder effect?
When a small group of individuals colonises a new/isolated area. Genetic drift has more of an effect on this population as it is smaller.
What is the bottleneck effect?
Populations may be suddenly reduced in numbers to a small size because of a dramatic environmental event OR human action. Genetic drift will have a large impact on these kinds of populations as they are very small.
Why does genetic drift impact on a small population more than a big one?
In a small population, accidental/natural death is more likely to lead to alleles becoming completely lost in a population, as only one or two members of that population carry that allele, so if they die off, the allele may be completely eliminated.
In a large population, accidental/natural death is less likely to lead to alleles becoming completely lost in a population, as many members of that population carry that allele, so if they die off, the allele will be likely to be present in the population.
