Final answer:
Ontogeny, or the development of an individual organism, is not considered evolution. Development is the changes occurring during an organism's life due to gene expression and interaction with the environment, while evolution involves changes in the genetic composition of populations over time.
Step-by-step explanation:
No, the development, or ontogeny, of an individual organism is not considered evolution. Ontogeny refers to the growth and development that occurs in the life of an organism, whereas evolution refers to the change in the genetic makeup of a population over generations. Early hypotheses like "ontogeny recapitulates phylogeny" suggested that individual development mirrored evolutionary stages, but modern biology has refined these concepts significantly.
While individual organisms do develop and exhibit changes throughout their lives, these changes are a result of their genetic code expressing itself in an interaction with the environment. Important to note is that an individual's genetic composition does not change through ontogeny, so it does not experience evolution. Evolution is rather the change in the genetic characteristics of a population over time, often many generations, due to processes like natural selection, mutation, and speciation.
Organisms can have different development patterns; for instance, mammals typically have a determinate development where they reach a finite adult stage, whereas plants can have indeterminate development, continuing to grow and change without a predefined endpoint. This development is an essential aspect of biological life, but it is distinct from the evolutionary processes that describe changes in populations over time.