9) Evo devo model organism (by Theodor Zbinden)

Evolutionary Developmental Biology is a field of understanding how development is optimized over evolutionary time.  Developmental Biology and Evolutionary Biology were joined because of their conceptual links between the two disciplines.  The classical model animals for molecular developmental biologist in the past have been Caenorhabditis elegans (C. elegans), Drosophila melanogaster (fruitfly), Xenopus tropicalis/laevis (frog), and Mus musculus (the laboratory mouse).  These model organisms helped deciphering processes like cell differentiation, growth of tissues, organs and organisms.  On the other hand the evolutionary molecular biologists have used model organisms ranging from viruses to vertebrates.  The evolutionary biologists also developed a wide variety of laboratory techniques analytical methods to uncover biodiversity and selection in populations.  Because a large proportion of evolutionary mechanisms like natural selection, act on phenotypes originated from development, the two fields discovered the much in common they have.  They realized that it would greatly benefit science if they would share each other and create a new scientific field named the evolutionary developmental biology.  The evo devo field has established to discover generative mechanisms underlying the evolution of organismal forms in short term and long term timescales.  However, to reach this goal they had to amplify the conventional model species until now.

Here some new model organisms used in the Evolutionary Developmental Biology:

 

 
Fig. A: Dung beetles of  the Onthophagus. The colors in the left picture, which are false, show which parts of the beetle body the horns grow from.  At the right a dung beetle.

A good example of a new model organism to study evo devo is the horned beetle.  The male animals have a wide variety of horns expressed in sexually dimorphic species of the Onthophagus.  This animal allows the study of poliphenism, the study of different phenotipes in the same population but not caused by different genetic types and the environmental control over that phenotype.  Results can give clues about microevolution and macroevolution.

Fig. B:  Water fleas of Cladocera.  At the right side different phenotypes of the head region, at the right side a water flea.

 Another model organism is the cladoceran genus Daphnia pulex also known as water fleas.  It is a model well known in science since it was a subject in ecological, toxicological and evolutionary studies for a long time.  Nevertheless the organism was not utilized in the modern molecular biology, the availability of the genome and the genetic map makes it a good candidate for evo devo.  The phenotypic plasticity of the water flea holds a great potential for future evo devo research.

References:

R. A. Jenner, M. A. Wills, (2007). The choice of model organisms in evo–devo. Nature Reviews Genetics 8, 311-314.
M. C. Milinkovitch’s laboratory. Citing Website. Laboratory of Artificial & Natural Evolution. Retrieved February 23, 2013, from http://www.lanevol.org/LANE/Introduction.html