Adjustment of layers of iridophore cells in some animals accounts for what?

Question

What is a present term for the 15th and 16th century transfer of plants, food crops, animals, culture, people, technology, diseases, and ideas between the "New World" of the Americas and the "Old World"?

Answer 1

Ability to change skin colour and patterns
As part of their skin, chameleons have two superposed thick layers of iridophore cells - iridescent cells that have pigment and reflect light - and chameleons change their skin colour by changing the structural arrangement of the upper cell layer by relaxing or exciting the skin.