Trees produce oxygen in order for us to breathe. if we cut them down there is less oxygen for us.
in an area of wildlife many different animals survive off of trees. cutting down the trees could lead to the extinction of specific animals.
Salutations!
A group of cells working together are called tissues. Organisms are made up of this structure. Cells are the smallest unit of life. A group of tissues working together is called organ. A group of organs working together is called organ system. An organ system working together makes up an organism.
Hope I helped (:
Have a great day!
I'm not sure if I will answer the question you asked, as I many have interpreted it incorrectly. In natural selection, there must be variance in the gene pool, the total frequency of alleles in a population. Now, one of the organisms may have a gene that somehow helps them survive from the selective force much better compared to the others. If this does happen, over time the gene pool will narrow down to become just the genes of that organism that survived better in the first place because the rest would be taken care of by the selective force. So, the alleles and trait come from the first organisms that had the advantage over the others of its species.