Changes in the physical environment, whether (1) occurring or ( induced, have thus contributed to the expansion of some (3) the (4) of new distinct species as populations diverge under different conditions, and the decline–and sometimes the (5) –of some species.

Changes in the physical environment, whether naturally occurring or human induced, have thus contributed to the expansion of some species, the emergence of new distinct species as populations diverge under different conditions and the decline - and sometimes the extinction - of some species.