1. Organisms of the same species at the same level of descent from a common ancestor

natural selection
adaptation
trait
population
generation

the organisms are not adapted to live in some communities or habitats.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.