The origin of a curved beak

Marta Linde-Medina
New York Medical College
Presented in the Embryo Physics Course, March 28, 2012


How a structure has evolved depends on how it develops. A present evo-devo model for the bird beak, a classical system in evolutionary biology, is based on the idea of a genetic program for development, i.e. that the beak form is the direct manifestation of gene expression; physics are absent from this model. Being inspired by finches, however whose adult beaks do not depart substantially from a triangular shape, the model does not address the origination of other divergent and common forms in birds such as, for example, a curved or parrot-like beak. A curved beak is a form within the plastic repertoire of the chicken embryo. The systemic administration of several chemicals capable of altering development (teratogens) result in the formation of a curved beak similar to those observed in parrots and some other bird genera. In explaining the cause of an induced curved beak in the chicken embryo, I will show the need of incorporating physics into a model for beak development.




I am biologist and my research interest is in the field of morphology. In my PhD (Mediterranean Institute for Advanced Studies,Spain) I proposed a new combination of statistical tools for testing adaptative hypothesis in morphology and I also started a theoretical work on key concepts in evolutionary biology (adaptation and exaptation). During my postdoctoral research (New York Medical College,USA;University of Manchester,UK) I have continued my work in the field at both the theoretical and the empirical level. I have outlined two approaches to the study of biological form: the internalist and the externalist perspective. The standard theory of evolution belongs from the externalist side; the internalist side is embodied on what is called physicalist evo-devo. At present, I am contrasting these two viewpoints in the bird beak.



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