Final answer:
A species is adapted to a particular habitat when it has traits that have become more common in the population over time because they increase the organism's fitness in that environment. These traits, known as adaptations, can be physical, behavioral, or physiological, and they help the species to survive and reproduce.
Step-by-step explanation:
To say that a species is adapted to a particular habitat means that over time, traits that increased the fitness of individuals in this habitat became increasingly frequent in the population. An adaptation is a heritable trait that aids the survival and reproduction of an organism in its present environment. As a consequence of evolution by natural selection, adaptations enhance the reproductive potential of the individuals exhibiting them, as well as their ability to survive to reproduce. Adaptations may include physical features, behaviors, or physiological processes that are suited to the environment, such as the webbed feet of a platypus for swimming or the thick fur of a snow leopard for living in cold conditions. Over generations, those individuals with traits that provide a better "fit" are more likely to survive and pass their genes on to the next generation, leading to a population that is well-suited for its environment.