Question

1. Explain how natural variations in expression of a TGF-β involved in bird beak size (higher expression levels lead to a large beak, lower expression levels lead to a smaller beak) could contribute to the evolution of different finch species.

Answer 1

TGF-beta (Transforming growth factor beta / TGF-β) is a type of cytokine that controls proliferation, cellular differentiation, and other functions in most cells. TGF-beta, is a factor synthesized in a wide variety of tissues. As in this case the higher expression levels implies the number of proteins are highly synthesized and the lower expression levels are the low amount of proteins formed and expressed. Therefore, the Finch species in which the TGF allows greater amount of protein production and their expression leads to large beak size and the lower amount of protein production and its expression leads to smaller beak size.