3.6 Evolution of species Flashcards
what is a mutation?
A mutation is a random change to genetic material.
What 3 effects may mutations have on an organism?
They can be advantageous, disadvantageous or neutral
what are 2 environmental factors which increase the rate of mutations?
radiation and some chemicals.
What is an Allele?
Different forms of a gene e.g. the gene for eye colour has the alleles brown, blue etc.
What is speciation?
The formation of a new species.
How is variation on a population created?
Through the build up of many mutations in a population
What is an adaptation?
An allele (inherited characteristic) that allows an organism to survive better in its environment.
What is natural selection?
The increase in the frequency of alleles in a population that allow organisms to survive.
How do favourable alleles increase in frequency in a population?
Those organisms that have alleles making them better adapted, survive and reproduce passing on those alleles to their offspring.
What is an isolation barrier?
During speciation an isolation barrier is something that stops sub groups in a population from reproducing.
What three different types of isolation barrier are there?
Geographical, ecological and behavioural.
Give an example of a geographical barrier
Rivers, mountain ranges and continental drift.
Give an example of a behavioural barrier
Two sub groups in a population not responding to each other’s mating calls.
Give an example of an ecological barrier
Two sub populations of plants tolerating different soil pH
After an isolation barrier splits a population into different sub groups, what is the next stage of speciation?
DIFFERENT mutations occur in each sub population.
