4.4 Genetic Diversity & Adaptation Flashcards
Define population.
All 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
What advantage does a high genetic diversity provide?
Ability to adapt to a change in environment
Allows natural selection to occur
Explain how natural selection results in devlopment of new characteristics.
Random mutations result in new alleles
Some alleles provide an advantage, making an individual more likely to survive and reproduce
Offspring receive new allele and frequency continues to increase over many generations
What is directional selection?
Occurs when environmental conditions change
Individuals with phenotypes suited to the new conditions will survive and pass on their genes
Over time the mean of the population will move towards these characterstics
Describe an example of directional selection.
Antibiotic resistance
Bacteria with a mutation allowing them to survive in the presence of antibiotics will reproduce
Frequency of the allele will increase and the population will shift to have greater antibiotic resistance
What is stabilising selection?
Occurs when environmental conditions stay the same
Individuals closest to the mean are favoured and any new characteristics are selected against
Results in low diversity
Describe an example of stabilising selection.
Birth weight
Babies that weigh around 3kg 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 are the 3 types of adaptation?
Anatomical
Physiological
Behavioural
What are anatomical adaptations?
Changes to body structure
What are physiological adaptations?
Changes to bodily processes
What are behavioural adaptations?
Changes to actions
