Genetic Diversity Flashcards
Why does DNA within a species vary very little?
Because all the members of one species will have the same genes.
What causes genetic diversity in a species?
Members of the same species don’t all have the same alleles.
It’s differences in alleles that create genetic diversity in a species (or in a population of a species).
Why is genetic diversity important?
It can help a population or species to survive.
It means that if the environment changes, there are likely to be some organisms with the alleles that enable them to survive the new conditions.
What are factors that increase genetic diversity?
Mutations in the DNA- forming new alleles.
Gene flow- this is where different alleles move between populations when individuals from one population migrate into another and reproduce.
What are factors that decrease genetic diversity?
Genetic diversity can be decreased by a number of factors including: genetic bottlenecks, the founder effect and selective breeding.
What is a genetic bottleneck?
An event that causes a big reduction in a population, e.g when a large number of organisms within a population die before reproducing.
This reduces the number of different alleles in the gene pool and so reduces genetic diversity.
The survivors reproduce and a larger population is created from a few individuals.
What is the founder effect?
Describes what happens when just a few organisms from a population start a new colony.
Only a small number of organisms contribute their alleles to the gene pool, so genetic diversity is reduced.
There’s more inbreeding in the new population, which can lead to a higher incidence of genetic disease.
What can the founder effect occur as a result of?
Migration leading to geographical separation or if a new colony is separated from the original population for another reason.
What is an example of how genetic diversity is brought about by something other than natural events?
Selective breeding- involves humans selecting which domesticated animals or plants reproduce together in order to produce useful characteristics e.g high yield.
Arguments for selective breeding?
It can produce high yielding animals and plants.
It can be used to produce animals and plants that have increased resistance to disease. This means farmers have to use fewer drugs and pesticides.
Animals and plants could be bred to have increased tolerance of bad conditions e.g drought or cold.
Arguments against selective breeding?
It can cause health problems.
It reduces genetic diversity- which results in an increased incidence of genetic disease and an increases susceptibility to new diseases because of lack of alleles in the population.
