(divergence) The development of different forms from a single basic structure as a result of different selective pressures acting on that structure. These changes may be associated with a new function that is added to or replaces the original function. For example, the general form of the angiosperm stem is aerial and elongated. Its function is to support and space out the leaves and flowers as well as conducting food and water. However certain xero-phytic plants with reduced leaves have expanded leaflike stems to increase photosynthetic capacity. Other plants have short swollen stems that serve as underground perennating organs. See adaptive radiation , homologous. |
