Chitin is a natural biopolymer that is made of the N-acetylglucosamine, modified glucose.
Chitin is an important polymer mainly for the fungi and the arthropod insects as it is present in the cell wall of the fungi and the exoskeleton of the insects.
The chitin provides a protective function to this organism that the digestive enzymes cannot degrade this chitin but only the symbiotic bacteria can digest eat therefore they are sometimes avoided to be eaten.
Charles Darwin had concluded that these birds had somehow evolved to adapt based on the island they were on. Each island had different food sources so if these finches wanted to survive they had to change. Each finch adapted to their environment due to forcefully evolving to survive.
This is a negative feedback. A negative feedback is where the body detects a change in the body's internal environment and crafts a mechanism to correct it
