Unit 3.2.3 - Genetic Diversity Flashcards
What creates genetic diversity in a species?
When they have different combinations of alleles.
What is genetic diversity?
The genetic differences between individuals within a population.
What is allele frequency?
How often a particular allele occurs within a population.
What is gene pool?
The complete range of alleles in a population.
What is gene flow?
Where alleles move between populations when individuals from one population migrate into another and reproduce.
What two things reduce genetic diversity?
Genetic bottlenecks and selective breeding.
What is genetic bottleneck?
An event causes a population to decline.
This reduces the number of different alleles in the gene pool.
When the surviving population reproduce the new population is created from a few individuals.
This creates a smaller gene pool a so reducing genetic diversity.
Name one type of genetic bottleneck?
The founder effect.
What is the founder effect?
A small group of individuals may migrate away or become isolated from the population.
The new founding population is made for a small number of inidviduals.
This reduces the gene pool and so genetic diversity.
Why does the founder effect often lead to higher incidence of genetic diseases?
There can be a lot of inbreeding within the population which means the alleles which cause the genetic disease may become more frequent.
Other than the founder effect why could the founding population be very different?
They may have evolved to live in a different environment.
What is selective breeding?
Humans selecting which domesticated animals or strain or plants reproduce together in order to produce successful characteristics.
How does selective breeding reduce genetic diversity?
Organisms with the desired characteristics will only be bred with similar organisms.
This means similar alleles are bred together.
Reducing the gene pool and so genetic diversity.
Give three arguments for selective breeding.
- ) Produce higher yielding animals and plants.
- ) Animals and plants have increased resistance to disease.
- ) Animals and plants could be bred to have advanced tolerance of bad conditions.
Give three reasons against selective breeding.
- ) It can cause health problems - increased incidence of genetic diseases.
- ) Reduces genetic diversity.
- ) If a new disease came about none of the alleles left may have resistance to the disease which means they are likely to catch it and die, wiping out the population.
