4.4 Genetic Diversity & Adaptation Flashcards
(23 cards)
Define population
All the organisms of a particular species that live in the same place.
What is an allele?
Different forms of a particular gene, found at the same locus (position) on a chromosome. A single gene could have many alleles.
Define genetic diversity
The total number of different alleles in a population.
Advantage of High Genetic Diversity
Ability to adapt to a change in environment; allows natural selection to occur.
How does natural selection result in new characteristics?
- Random mutations result in new alleles.
- Some alleles provide an advantage, making an individual more likely to survive and reproduce.
- Their offspring receive the new allele, and the frequency continues to increase over many generations.
What is directional selection?
A type of natural selection that occurs when environmental conditions change.
What happens to individuals with phenotypes suited to new environmental conditions during directional selection?
They will survive and pass on their genes.
What is the effect of directional selection on the mean of the population over time?
The mean of the population will move towards the characteristics suited to the new conditions.
What is an example of directional selection?
Antibiotic resistance.
How do bacteria develop antibiotic resistance?
Bacteria with a mutation allowing them to survive in the presence of antibiotics will reproduce.
What happens to the frequency of the antibiotic resistance allele in bacteria?
The frequency of this allele will increase.
What is the result of increased antibiotic resistance in a bacterial population?
The population will shift to have greater antibiotic resistance.
What is stabilising selection?
A type of natural selection that favors individuals closest to the mean.
When does stabilising selection occur?
When environmental conditions stay the same.
What happens to new characteristics during stabilising selection?
They are selected against.
What is the result of stabilising selection on genetic diversity?
It results in low diversity.
What is an example of stabilising selection?
Birth weight
What birth weight is associated with higher survival rates in babies?
Around 3kg
Why do babies that weigh around 3kg have a higher likelihood of survival?
They are more likely to survive than those at lower or higher weights.
Define a niche
The role of a species within its environment. Species sharing the same niche will compete with each other.
What is an anatomical adaptation?
Changes to body structure, e.g. oily fur.
What is a physiological adaptation?
Changes to bodily processes, e.g. venom production.
What is a behavioral adaptation?
Changes to actions, e.g. hibernation.
