Natural selection

Question 1

What are selection pressures?

Answer 1

Factors that affect an organism’s chances of survival/reproductive success

Question 2

Why do different organisms within a species exhibit differences in their characteristics?

Answer 2

Due to genetic variation

Question 3

What is survival of the fittest?

Answer 3

The idea that organisms whose characteristics are best adapted to a selection pressure have an increased chance of surviving and successfully reproducing

Question 4

How does survival of the fittest lead to natural selection?

Answer 4

Organisms that possess the advantageous characteristic (and so the advantageous alleles) are more likely to survive and pass said gene onto their offspring. Conversely, organisms without the advantageous gene are less likely to survive and pass on their version of the gene.
Over time, the proportion of individuals with the advantageous adaption increases, hence the frequency of the allele that codes for this particular characteristic increases in the gene pool