Ontogenesis

Ontogenesis, also known as ontogeny, refers to development of an organism, an anatomical feature, or behavioral feature from its earliest stage until its completion.

For instance, a scientist might study the growth of a organ from its earliest stage in the developing fetus until the death of the organism being studied. Ontogenesis or ontogeny is the developmental study of an organism within its own specific and personal lifetime. This differs from phylogeny which is the evolutionary history of a species (and related species) through genetics.