Why would the solstice be important to
an ecosystem?

marks an important milestone. It's the shortest day of the year and the longest night of the year, and signals a powerful transition point between seasons that is impossible to ignore. ... In Pagan times the winter solstice was referred to as Yule and was a celebration of the Goddess (Moon) energy

Explanation:

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).