Primary succession occurs in places that have never been occupied by a community. Simple species are established first, as they help enrich the soil, allowing other species to become established. The first organisms to appear in areas of primary succession are often pioneer species such as mosses or lichens.
The carbon atom has unique properties that allow it to form covalent bonds to as many as four different atoms, making this versatile element ideal to serve as the basic structural component, or “backbone,” of the macromolecules. Individual carbon atoms have an incomplete outermost electron shell.
A single species that has evolved into several different forms that live in different ways has undergone "b. convergent evolution" since the multiple "divergent" species are seen to "converge" into a single species if you go back far enough in time.
