Genetic diversity and adaptation (9) Flashcards
What is a population?
all the organisms of a particular species that live in the same place
What is meant by genetic diversity?
total number of different alleles in a population
What is the advantage of having a high genetic diversity?
ability to adapt to a change in environment which allows natural selection to occur
What are the 2 types of selection?
directional
stabilising
What is directional selection?
when individuals with phenotypes suited to new conditions will survive and pass on genes, overtime the mean of the population will move towards these characteristics
When does directional selection occur?
when environmental conditions change
What is an example of directional selection?
bacteria with antibiotic resistance mutation
What is stabilising selection?
when individuals closest to the mean are favoured, resulting in low diversity
When does stabilising selection occur?
when environmental conditions stay the same
What is an example of stabilising selection?
birth weight - babies around 3kg are more likely to survive than those at lower or higher weights
What is a niche?
role of a species within its environment
What happens if 2 species in the same environment share a niche?
they will be competing with each other
What are the 3 steps in how natural selection results in the development of new characteristics?
1) random mutation results in new alleles
2) some alleles provide advantages, making individual more likely to survive and reproduce
3) their offspring receive new allele and frequency of allele continues to increase over many generations
What are 3 types of adapation?
anatomical
physiological
behavioural
What is an anatomical adaptation?
change to body structure e.g. oily fur
