4.4 Gentic Diversity and Adaptation Flashcards
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
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 development of new characteristics
Random mutations results in new alleles
Some alleles provide an advantage, making an individual more likely to survive and reproduce
Their offspring receives the 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 characteristics
Give an example of directional selection
Antibiotic resistance. Bacteria with a mutation allowing them to survive in the presence of antibiotics will reproduce. Therefore frequency of this allele will increase and the population will shift to have greater antibiotic resistance
What is stabilising selection
Occurs when an environmental conditions stay the same. Individuals closest to the mean are favoured, and any new characteristics are selected against
Results in low diversity
Give 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 niche
The role of a species within its environment. Species sharing the same niche will compensate with each other
What are the three types of adaptations
Give examples of each
Anatomical (changes to body structure ) e.g. oily fur
Physiological (changes to bodily processes) e.g. venom production
Behavioural (changes to actions) e.g. hibernation
