What is the adaptive reason for low levels of melanin at higher latitudes?

The adaptive reason which is for low levels of melanin at higher latitude is because of lower levels of melanin at higher latitudes is because of lower levels of melanin which lead to higher vitamin D.

Absorption at higher latitudes. Melanin is produced by oxidation of amino acid tyrosine which is followed by polymerization. They are being produced in a specialized group of cells which are known as melanocytes.

The three basic types of melanin include; neuromelanin, pheomelanin, and eumelanin.