Evolutionary developmental biology is the study of how changes in the early development of young living things have led to a wide variety of life forms. The term is often abbreviated evo-devo. It deals with the young of multicellular organisms. Multicellular organisms are living things with more than one cell. At an early stage of development, called the embryo, such young undergo dramatic changes in structure and form. Differences in structure and form also appear across different species with a common ancestor. For such differences to have evolved (developed over time), scientists realize that they must have an underlying cause in changes in embryonic development. Evolutionary developmental biology concerns the relationship between changes in embryonic development and the evolution of a wide diversity of species (kinds of living things).
Evolutionary developmental biology became an important field of study in the middle to late 1900’s. At that time, scientists discovered that all animals use the same basic set of genes to regulate the formation and patterning of the body during development. Genes determine which traits living things inherit from their parents.
In experiments with fruit flies, scientists discovered that mutations (changes) in certain genes cause major changes in body development. For example, certain mutations could produce flies with extra body parts or other abnormal features. In 1983, two separate teams of scientists first identified a set of such genes called homeobox genes. One team was in Switzerland, and the other in the United States. Homeobox genes regulate the development of an embryo. They control when and where specific tissues and cell types form in the embryo (see Homeobox genes ).
Scientists have since identified other genes that regulate overall body development. All such genes work by turning other genes on and off. For this reason, they are often called master regulatory genes. Studies in evolutionary developmental biology often focus on identifying mutations in a master regulatory gene. Such mutations may change the timing or location of gene action. They may also change gene interactions in developing organisms. Scientists are learning that the remarkable diversity seen among millions of animal species can result largely from mutations in a relatively small number of regulatory genes.
Because of their role in embryonic development, master regulatory genes are often also involved in the development of birth defects. Scientists studying evo-devo thus also gain insight into how birth defects occur and how they may be treated or prevented (see Birth defect ).
See also Developmental biology ; Evolution .
