Note that many animal species have the ability to store millions of sperm or fertilized eggs from other individuals for many years. Such a behaviour might be a

Note that many animal species have the ability to store millions of sperm or fertilized eggs from other individuals for many years. Such a behaviour might be a way to increase genetic diversity while populations are tiny. Note that tiny populations can occur frequently when the environment has millions of barriers between tiny populations - eg. a water dwelling creature living in millions of tiny pools and unable to pass from one pool to the next until there is a major flood, which might only be once per thousand years.