Types of Developmental Change (1 of 2)

Developmental changes have likely been involved in important morphological changes—like the evolution of novel and complex structures.

Here are a few of the sorts of developmental changes that may have been important:

Module duplication and adaptation
A module refers to a unit that can be duplicated and further adapted. For example, arthropods have various numbers of body segments. Segment duplication and loss is a developmental change that probably occurred many times in the evolution of this clade. The graphic below shows a hypothetical example of module duplication and adaptation.

Individualization
This is the modification of a particular module, usually when there is selection for a specialized function.


One set of scorpions’ appendages has evolved into pincers whereas the same appendage in many spiders has evolved into colorful pompoms used in mating rituals.

• Scorpion image courtesy of the California Academy of Sciences.
• Spider image courtesy of Michael Hedin, San Diego State University.