ibclogo XVI International Botanical Congess


Abstract Number: 4474
Session = 3.13.2


MORPHOLOGY AND PHYLOGENY - HOMOLOGY AND HOMOPHYLY


W. Hagemann, University of Heidelberg, Werderplatz 11a, D-69120 Heidelberg, Germany


Typological comparison opens understanding diversity of organismic construction. This method has also a propaedeutical function in respect to phylogenetic considerations. More than 200 years ago GOETHE observed: The position of construction elements is invariable whilst the diversity within a type results from the principle of variable proportions of these elements. Consequently, the typological method identifies construction elements of organisms independently of their function, form, and phylogeny. OWEN termed elements of equal position as homologous, elements of equal form and function in different positions as analogous. DARWIN used such typology as a propaedeutical method. Only after typological analysis phylogenetic hypotheses should be developed. But the postdarwinian definition of homology as common descent of organs made the propaedeutical typology impracticable because it turned the method into a theory. Therefore, the original term homology must be conserved and thus restricted to correspondence of positional relations of the elements of a type, whereas homophyly should be used to express common descent of construction elements. Practical consequences will be shown by selected examples.


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