During the warm temperatures of summer the arctic fox produces enzymes that cause it's for to become reddish brown. During the cold temperatures of winter, these enzymes do not work. As a result, the fox has a white coat that blends into the snow with the background

The expression of certain genes is affected by temperature

Explanation:

During the warm temperatures of summer the arctic fox produces enzymes that cause it's for to become reddish brown. During the cold temperatures of winter, these enzymes do not work. As a result, the fox has a white coat that blends into the snow with the background

The expression of certain genes is affected by temperature explains this change in color found in them to match the surrounding snow, this is the reason why during the spring and summer, it has a dark coat which help match the brown dirt in it environment