Heterobathmia

In evolutionary research, heterobathmia (different levels) denotes the simultaneous occurrence of original ( plesiomorphic ) and derived ( apomorphic ) features within the same clan or on the same organism . This can occur due to the different evolutionary speed of the individual traits. The term was coined in 1959 by the botanist Armen Tachtadschjan .

Heterobathmia is explained by the concept of mosaic evolution . It predicts that specific features of the same organism in the cladistic analysis of the systematic relationship with respect to an evolutionary ancestral form can be derived (specialized, imprecise, often “more highly developed”) or little changed (imprecise, often “primitive” or “basic”) , depending on which feature you are looking at. Real organisms are therefore not primitive or more highly developed, but they usually have derived characteristics in certain areas, while other characteristics of the same organism can be "primitive". In relation to the same characteristics, these relationships can be reversed in another, related organism. An organism that has individual "primitive" characteristics that have not changed much compared to the evolutionary parent form should therefore not be used as a model for the original state. In practice, every living organism can be seen as a mosaic shape . Heterobathmia means that evolutionary family trees that are only drawn up on the basis of a narrow base of characteristics, for example family trees of flowering plants solely on the basis of characteristics of the flower, often misrepresent the relationships.

literature

• Friedrich Jacob, Eckehart J. Jäger, Erich Ohmann: Botany 4th ed . Gustav Fischer Verlag, Jena 1994, ISBN 3-334-60812-3 .
• Armen Takhtajan: Flowering Plants. Second edition, 2009. Springer Verlag, 2009 ISBN 978-1-4020-9608-2 . (The evolution of angiosperms. Fischer Verlag, Jena, 1959).