DNA is found in the nucleus
Mammalia (mammals) have hair or fur and produce milk
Feeding relationships in which organisms feed on a variety of organisms is called a food web.
I believe that the best answer for this question is "gene mutations." Gene mutations can either take place through nucleotide substitutions, which occur when the the sequence of nucleotides are altered. Frameshift mutations can also occur. They involve the insertion or deletion of a DNA molecule's bases. Hope this helps.
