What happens to individuals that have advantageous characteristics?
Gain access to resources more quickly so reproduce more than those without. Advantageous alleles therefore shown more in the next generation.
What does ‘selected for’ mean?
When an allele that is advantageous is shown more in the next generation
What is a selection pressure?
An environmental factor that can alter the frequency of alleles in a population when it is limiting.
What is natural selection?
The increased chance of a survival and reproduction of organisms with phenotypes suited to their environment, enhancing the transfer of favourable alleles.
Give 4 examples of selection pressures.
- availability of nesting sites
- day length affecting reproductive behaviour
- overcrowded allows disease to spread (better immune system = passed on)
- predation
What individuals in the prey population are more likely to reproduce against the selection pressure of predation?
- better camouflaged
- mimic species who aren’t dangerous but mimic dangerous species
- those who survive best in certain temps
- those who resist habitat loss by humans
what does the term ‘fit’ describe?
How likely an organism is to survive, reproduce and pass on alleles to the next generation.
Why does the value of an allele depend on the environment?
The genotype that causes a phenotype stays fixed. It may be advantageous in one environment for some selection pressures but not others.
