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Posts Tagged ‘Philosophy and Genetics’

Could plasticity provide an evolutionary understanding of variation?

In Fabris, Philosophy of Biology on December 4, 2012 at 7:00 AM

C.H.Waddington’s genetic approach still remains contemporary, after more than half of a century from its first exposition. The reason of this is mainly because it sheds light on the organism/environment regulatory mechanisms that can step up the explanation of the morphological variations that we observe everywhere in the biological realms. Waddington was the first scholar showing how the selection of biological responses to a particular environmental stimulus influence  the direction of the evolutionary change (Waddington, 1953). In the last decade,s several authors stressed the necessity to expand the epistemological boundaries of the Modern Synthesis (e.g. Pigliucci, 2007). By this point of view, the integration –as Waddington first displayed– of ontogeny and development into evolutionary explanations may result essential for understanding the biological significance of  phenotypic  novelties. Adopting such EvoDevo approach, genetics and molecular biology concur to demonstrate how “regulation” and “organism/environment feedback” play a crucial role in expressing phenotypical variation (Hiyama et al., 2012). By this line of evidences, blowing up by the Waddington’s pioneristic work, emerge how the environmental changes may have some relevant effects, not merely selective as claimed by the neo-Darwinian tradition, in promoting the evolution of the genome. Irrespectively by the extend of these effects, we must then consider the genetic and epigenetic responses exhibited by the organisms as phenotypical cues of deeper evolutionary refinements and/or switching occurring in previous canalized pathways of development. However, the comprehension of the full range of genomics plasticity is not alone suffice to provide a satisfactory evolutionary understanding of the phenomenon of morphological variation. A balance between the capacity of the genome to respond plastically to the environmental stimuli and the adaptive “opportunity” to reveal mutations, need to occur at some point of the complex organism/environment interaction. If this not the case, we have a paradox by which the mechanisms responsible for the phenomena of phenotypical variation could lead not to evolutionary adaptation, but rather to an opposite effect.       

Bibliography 

Hiyama, A., Taira, W., & Otaki, J. M. (2012). Color-pattern evolution in response to environmental stress in butterflies. Frontiers in genetics, 3, 1-6.

Pigliucci, M. (2007). Do we need an extended evolutionary synthesis? Evolution, 61, 2743-2749.

 Waddington, C. H. (1953). Genetic assimilation of an acquired character. Evolution, 7, 118-12  

Flavia Fabris