… to reach leaves high on trees (function).
Second, experience plays an important role in the principle form follows function. In this scenario, a phenotype can be changed by experience. For example, an animal that chases prey extensively will likely develop higher cardiovascular fitness, and leaner muscle mass (form) than is usual. As a result, it could be said that these experientially-influenced changes follow the function of the animal (to chase prey).
Third, environment can be an important factor in form follows function. Here, environmentally-induced changes in phenotype can be argued to be the basis of form follows function. For example, in an environment of chronic stress, a specific taxon may show elevated stress hormone levels. Thus, it can be argued that the environment (stress) helps the animal increase stress hormones (form), thus enabling them to better deal with their environment (function).