U3 Key Area 6: Evolution Of Species Flashcards
What is the definition of mutation
A mutation is the random changing of an organisms genetic material.
What are mutations
Mutations are spontaneous
What can mutations cause
A mutation can cause a change in a phenotype (characteristic) of an organism.
What are mutations the only source of
Mutations are the only cause of new alleles.
What is a mutagenic agent
A facto or chemicals that increase the rate of a mutation
What can increase the rate of mutation
Environment factors such as radiation and some chemical gas
Examples of radiation (3)
- UV light
- Gamma rays
- X-rays
Examples of Chemical Gas (4)
- Alcohol
- Caffeine
- Mustard gas
- Chemicals in tobacco
Three possible effect of mutations on organism:
- Disadvantages to survival
- Advantages to survival
- Neutral
What do inherited characteristics help
That make an organism well suited to survive in its environment
Types of adaptions (3)
- Anatomical
- Physiological
- Behavioural
Why is variation important
To allow a population to evolve over time and in response to changing environmental conditions.
What are variations
New alleles produced by mutations result in plants and animals becoming better adapted to their environment
What are variations called evolutionary adaptions
They allow organisms to cope and evolve in response to environmental changes
What’s evolutions
The organisms with the advantageous mutations survive and pass them onto the next generation
What is natural selection
The basic mechanisms of evolution whereby organisms better adapted to their environment tend to produce more offspring.
Step 1 of natural selection
There is variation in the population
Step 2 of natural selection
More individuals are produced than the environment can support and Natural Selection occurs due to selection process. The individuals who are less well adapted do not reproduce and die out
Step 3 of natural selection
The best adapted individuals in the population survive to reproduce and pass on the favourable alleles that confer the advantage. This is sometimes knows as ‘Survival of the Fittest’
Step 4 of natural selection
The alleles increase in frequency in the population over time.
When do organisms (in the same species) show variation (4)
- Organisms produce too many offspring
- Struggle for existence follows (Survival of the Fittest) when there is selection process
- Offspring best adapted (suited) have the best chance of surviving, reproducing and passing on the advantageous alleles
- Theses alleles increase the frequency within the population
What is a species
A group of organisms which can interbreed and produce a fertile offspring
What is speciation
The development of new species
How long does it take for speciation to occur
This is something which happens over a very long period of time
What is speciation caused by (3)
- Geographical barrier such as oceans or mountains
- Ecological barriers caused by changes in abiotic factors such as temperature, pH, water etc.
- Behavioural barriers such as migration
What is the 1st step on speciation
It starts when a large group of organisms of the same species become separated into 2 or more groups
What is the 2nd step on speciation
On the main group has been split, mutation occurs within the smaller groups resulting in new alleles. This can alter the phenotype (characteristics) of the organism
What is the 3rd step on speciation
As time passes the environment applies slightly different selection pressures on the population and natural selection takes place.
What is the 4th step on speciation
These individuals then survive to reproduce and pass on new alleles
What is the 5th step on speciation
This results in the characteristics of the population changing
What is the 6th step on speciation
After a long time, even if the barrier is now removed, the 2 populations will differ from eachother so much that they are no longer able to interbreed and produce fertile offspring. Therefore they are now different species.
What is the hint to remember the steps of speciation
BIG- barriers
MAMA - mutation
NOT - natural selection
READY- reproduce
