Key area 6- Evolution of species Flashcards
What is a mutation?
A random change to genetic material
What are alleles?
Different versions of the same gene (e.g. blue eyes and brown eyes)
What does variation mean?
The difference within a population
What does natural selection mean?
The process in which evolution occurs
What does speciation mean?
The process that results in a species
What is an isolation barrier?
A geographical, ecological or behavioural means that separates two species
What is selection pressure?
A change in the environment for a living thing (e.g. a new predator appears in an ecosystem)
What does adaption mean?
An inherited characteristic that makes an organism well suited to survival in it’s environment/niche
What does evolution mean?
Evolution is the gradual change in organism over a very long period of time
What are the three possible outcomes for how an organism is effected by a change to it’s DNA?
Neutral- mutation has no effect on organism, Positive- Mutation causes organism to gain a survival advantage, Negative- Mutation causes organism to be at a disadvantage,
What 2 factors that effect rate of mutation?
- Radiation 2. Chemicals
Describe what happens during a mutation
A new source of alleles form a gene
Why do mutations happen?
Mutations are spontaneous
Where does variation come from?
Random and spontaneous mutations lead to different versions of genes.
Why is variation important?
It allows a population to evolve over time in response to to environmental condition changes
What does new alleles produced by a mutation result in?
It can result in plants and animals becoming better suited to their environment
What is the name of the scientific theory that explains how evolution happens?
Natural selection
When does natural selection occur?
When there are selection pressures on organisms- this could be a change in the environment, availability of food, new predators, disease temperature or light intensity
What are the 4 steps of natural selection?
(1) Species produce more fertile offspring than the environment can sustain. (2) The best adapted individuals in a population survive. (3) Survivors reproduce and pass on favourable genes with the selective advantage. (4) The favourable alleles increase in frequency within the population
What is the first stage of natural selection?
Species produce more fertile offspring than the environment can sustain
What is the second stage of natural selection?
The best adapted individuals in a population survive
What is the third stage of natural selection?
Survivors reproduce and pass on favourable genes with selective advantage
What is the last stage of natural selection?
The favourable alleles increase in frequency within the population
What are the 3 stages of speciation?
- Isolation 2. Mutation 3. Natural selection
What is isolation?
Part of the population becomes isolated by an isolation barrier- can be geographical, ecological or behavioural
Give 3 examples of geographical isolation barriers
Rivers, oceans, mountains
Give 2 examples of ecological isolation barriers
pH, different habitats
Give an example of a behavioural isolation barrier
Differences in mating behaviour
What occurs in the mutation stage of speciation?
Over a long period of time different mutations will occur in each sub population
What occurs in the natural selection stage of speciation?
There will be different selection pressures acting in the two groups. Each sub-population evolves until they become so genetically different that they are two different species.
