Some genetic mutations occur from exposure to external agents called such as radioactivity, ultraviolet radiation from the sun, and certain natural and human-made chemicals.

Some genetic mutations occur from exposure to external agents called mutagens, such as radioactivity, ultraviolet radiation from the sun, and certain natural and human-made chemicals.
A mutagen refers to all physical or chemical agents that change the genetic material, of an organism and thus increases the frequency of mutations. Mutagens may be of physical (like ionizing radiation, UV), chemical (reactive oxygen species, deaminating, alkaloids, bromines)  or biological origin (viruses, bacteria, transposons).

Used to water and cool climates, probably not thick coated or fluffy. they most likely have thin coats and have to survive to find food. sorry if this wasn't the answer you were looking for..: )