An example of Adaptation is an Antartic Fish. This fish has evolved to produce "anti-freeze" proteins in their blood, to survive the cold freezing temperatures in the water.
Behavioral Adaptation is changes in an organisms responses to help with their survival example (hibernation, migration, and instincts)
Physical/ Structural are characteristics that are made to the organism to appeal to mates or protect against predators. Examples include camoflauge, bright colors, size changes etc.
Evolution shows that overtime organisms have adapted to certain conditions that differ from its original structure. This relates to adaptation as they correspond with each other as an organism changes through adaptation, it evolves vice versa. This is relative to many organisms such as birds who vary in size to their environment contrast to their ancestors who are unlike todays birds.
The population of species decreases, it is not uncommon for many species, as some have gone extinct as they were unable to survive due to their condition.
Charles Darwin and Alfred Wallace developed the theory of natural selection. Wallace believed that the evolution was connected to the adaptation of organisms to changing environmental conditions.
The significance of adaptation is to understand the process on why organisms are more suited to conditions than others. The direction selection of species and how it maintains balance. Adaptation plays a role in predators, prey, bacteria, plants, etc. The importance of it is, is that it's the most essential factor in living beings.