Natural Selection Flashcards
How does genetic variation exist within populations
Due to the existence of different alleles
What does the existence of alleles mean
There is differential reproductive success between organisms with different alleles of the same gene
What occurs under certain environmental conditions
Certain alleles suited to the conditions will have an increased chance of survival and reproduction
How can new alleles arise
Through random mutation
How can natural selection effect alleles
Can cause the frequency of alleles in a population to change over time
What will happen if an allele that has risen as a result of mutation is harmful
The mutated allele will quickly die out
What will happen if an allele that has risen as a result of mutation increases the chance of survival
The frequency of the allele will increase within the population
What process other than natural selection can affect allele frequencies in a population
Founder effect, Genetic Drift, Bottleneck effect
How does founder effect occur with Anole Lizards
They inhabit most Caribbean Islands and they can travel from one island to another via floating debris. The individual lizards that arrive on an island is completely up to chance
What is genetic drift
When a population is significantly small, chance can affect which alleles get passed onto the next generation. Over time, some alleles can be lost or favoured purely by chance.
What is the bottleneck effect
When a previously large population suffers a dramatic fall in numbers. E.g. due to a major environmental event. In turn reducing the genetic diversity in the population as alleles are lost, surviving individuals end up breeding and reproducing with close relatives.
What happens as a result of selection pressures
A change in allele frequencies over time
