4B- Genetic Diversity And Natural Selection Flashcards
What is genetic diversity?
The number of different alleles in a population.
What increases genetic diversity?
More unique alleles in a population.
Mutations in DNA- forming new alleles.
Different alleles being introduced into a population when individuals from another population migrate into them and reproduce.
(This is gene flow)
What is a genetic bottleneck?
It’s an event that causes a big reduction in a population.
Eg. A large number of the population die.
This reduces the number of alleles in the gene pool, reducing diversity.
The survivors reproduce and a larger population is created from a few individuals.
What is the founder effect?
It occurs when a few organisms from a population start a new colony.
The frequency of alleles may be different from the original population.
Alleles for genetic diseases may be higher.
The founder effect can occur due to migration leading to geographical separation or religion.
How does natural selection change the alleles in a population?
Random mutations may lead to a new allele.
This can be harmful meaning it does out as the animal isn’t able to reproduce and pass on the gene.
It can also be beneficial helping it to survive and mate to produce fertile offspring, increasing he frequency in the population. This is known as natural selection.
How does natural selection work?
Not all individuals are as likely to produce as others. There’s differential reproductive success.
Those who have alleles that increase their survival are more likely to survive and reproduce.
This means a greater proportion of the next generation inherits the beneficial allele.
The frequency of this allele increases.
Over generations this leads to evolution as the advantageous alleles become more common in the population.
Natural selection leads to populations becoming better adapted in three ways. What are the three ways?
Behavioural adaptations- The way an organism acts to increase survival and reproduction.
Eg playing dead.
Physiological adaptation- Processes inside the animal that increase survival.
Eg hibernation. This lowers their metabolism, conserving energy so they don’t need to look for food when it is scarce.
Anatomical adaptations- Structural features that increase the chance of survival.
Eg. Whales have a thick layer of blubber that keeps them warm.
