The study of energy and its changing form is called

The study of energy and its changing form is called thermodynamics. Thermodynamics is the branch of physical science that is concerned with conversions between heat and other forms of energy such as chemical, electrical or mechanical energy. Under thermodynamics, energy can be transferred from one place to another and from one form to another.

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.