Many trees seems to readily survive the loss of their leaves even though they are the main photosynthesizing organ.how is this possible?

Trees have storage parts

Explanation:

Most tree survive the loss of their leaves due to ability of their roots and stem to store produced glucose by photosynthesising leaves into starch for future use.

On his visit to the Galapagos Islands, Charles Darwin discovered several species of finches that varied from island to island, which helped him to develop his theory of natural selection.

Darwin's finches are a classical example of an adaptive radiation. Their common ancestor arrived on the Galapagos about two million years ago. During the time that has passed the Darwin's finches have evolved into 15 recognized species differing in body size, beak shape, song and feeding behaviour.

Society is a group of individuals being involve in social interaction sharing the same territory thus society enables the members to benefit in ways that cannot be done only individually like protecting everyone from predators. It would be good to have a society and also for territorial purposes.