Bacteria that resist a hospital's antibiotics rapidly multiply as other bacteria die off. this best illustrates

It demonstrates natural selection since the the bacteria that are resistant are selected for because they are the ones that survive. These resistant bacteria -since they are still living- multiply (thus leaving "offspring") and are able to keep their species in existence which adds to their fitness.

small, big, or no change could occur in the phenotype. it could cause something as simple as a cats ears to curl backwards or something as frighting as death. it could also occur in the protien-coding area and have an effect on that but no effect on the amino acids. what has to occur is a changing in the hox gene or the control gene.