There are three types of polar bears - ones with thick coats, ones with thin coats, and ones with medium coats. It is fall and soon it
will be winter. the temperatures are dropping rapidly and the bears
must be kept warm or they will freeze to death. the bears have had
an average of 2 cubs each, but due to the extreme temperatures,
many mother bears have only one cub left.

Darwin's first point is "A population has variations."
What are the variations discussed in the scenario above?