Coral and algae have a reciprocal relationship in which the algae perform photosynthesis, providing the coral with some nutrients and with the calcification process. in return, the coral provide the algae with certain nutrients and a place to live in a lighted environment. this is an example of a relationship.

The images show two species of tree frogs in a particular region. the gray tree frogs are adapted to the trees of the woodlands, while the green tree frogs can survive in woodlands or grasslands. the gray frog was abundant in the woodlands. because of climatic changes, most of the trees in the region died, and the woodlands changed to grasslands. in such a case, the . the gray tree frog is closely related to the green tree frog genetically, but they have different mating calls. this suggests that speciation occurred because of .