They are directly related. The more different trees, the more different birds because not all birds like the same trees:
Some like higher trees to build higher nests, others like lower trees, some like the leaves of some trees useful, some live in the trees that give them fruits, other in trees where many insects go, etc.
Hope it helped!
I think the best phrase to describe this would be Founder effects. Founder effects occurs when a new colony is started by a few members of the original population. This small population size means that the colony may have; a non-random sample of genes in the original population. Reduced variation from the original population.. According to Bottlenecks and founder effects, genetic drift can cause big losses of genetic variation for small populations.
Microtubules are long,hollow protein cylinder that form a rigid skeleton for the cell golgi apparatus
~Jurgen