Answer:
The ecosystem is adversely affected.
Explanation:
The ecosystem is adversely affected due to clearing of all trees and bird population is also adversely affected because these trees are the source of habitat for these birds. When there is large number of birds in an ecosystem so the bird population automatically increases due to the presence of more habitat for the birds so if all the trees are removed so very little population of birds left in that ecosystem and this action leads to great disturbance in the ecosystem.
The type of evolutionary mechanism that occurred was natural selection
He wanted to see how different traits passed through the pea plants he grew. To do this, he needed to cross polliante so that their were multiple parents affecting the genes of the new pea plant. If he self pollinated, all the new baby pea plants would Look the same as their parents and we wouldn't know as much as we do about genetics now