10) Evolutionary Developmental Biology or Developmental Evolutionary Biology? (by Theodor Zbinden)

 I asked myself why sciences call this new field evo devo and not devo evo?  A simple question I thought, but when I looked for information I realized it is a philosophical question and some people published different articles about this specific issue.

On one side is Brian K. Hall, Research Professor Emeritus at Dalhousie University in Halifax, Nova Scotia.  Hall is an active participant in the evo devo debate and by the way, is the person who proposed the new concept that the neural crest tissue of vertebrates may be viewed as a fourth embryonic germ layer. 

For Brian Hall evo devo and devo evo are not the same concepts and there exists a great difference between each strategy.  He mentions that evo devo continues the view of the evolutionary embryology of the nineteenth century, attempting to explain the cause of the origin of phenotypes.  He represents the view of evo devo as it should produce properties and results not found neither in Evolutionary biology nor Developmental biology alone.   But for Hall the evo devo until now could not answer all questions of the teorie that tryes to answer the question of how developmental processes mediate the translation/transformation of the genotype into the phenotype.  and many researchers tried to complete with  However, for Hall the Neo-Darwinism (the theory that evolution consists of the result of mutations and natural selection) is until now incomplete and a way to fill the remaining caps could be with the Devo evo concept.  The devo evo theory could complement the present Neo-Darwinism few or even replace it.  Hall thinks even farther in his vision of devo evo, for him the genes would not be anymore the main players of the evolutionary changes.

On the other hand is Scott Gilbert, author of the text books like Developmental Biology (six editions), A Conceptual History of Embryology and Embriology: Constructing the Organism. 

For Scott the issue is a matter of definitions, how the terms are definite.  He thinks that most people believe that evo devo is a simple synthesis of evolutionary biology and developmental biology, but in fact it is not that way.  The evo devo concept includes much more than just evolution and development; in addition it contains also paleontology (the study of ancient life), morphometric (Quantitative analysis of forms like size and shape), ecology (relationship between organisms and the natural environment), life history strategy research (key events to produce the largest possible surviving offspring’s is shaped by natural selection) and functional morphology (relation between structure and function of morphological features).  On the other hand not all parts of evolution and development are involved in the evo devo concept.  Scott says for him evo devo is an interaction between “population genetic models of evolution and developmental genetic models of evolution”.  The two models are based on genes, one model focuses on frequencies of gene variants within a population and the other model evolution depends on variation of gene expression between populations.

As a result of these two leading voices in evolutional bilogy and developmental biology about evo devo or devo evo we can resume that it is on debate how to name the new branch in biology.  Nevertheless it shouldn’t be a point of discussion because it’s a matter from which direction the problem is faced. 

Reference:

G. F. Scott, (2003). Evo-Devo, Devo-Evo, and Devgen-Popgen, Biology and Philosophy 18: 347–352.

B. K. Hall, (2000). Guest Editorial: Evo-devo or devo-evo—does it matter? Evolution and Development 2:4, 177–178.