|Similarity: conformity of one or more - but not all - properties of two or more objects._____________Annotation: The above characterizations of concepts are neither definitions nor exhausting presentations of problems related to them. Instead, they are intended to give a short introduction to the contributions below. – Lexicon of Arguments. |
Similarity/Mayr: not all similarities of organisms are based on homology: three kinds of characteristic changes can simulate homology:
1st Convergent evolution: independent acquisition of the same characteristic in unrelated lines of descent, e.g. wings in birds and bats.
2nd Parallel evolution: the same with related descent lines due to genetic predisposition for this characteristic, even if it was not phenotypically pronounced in the ancestors. For example, independent acquisition of goggles by a whole family group of flies.
3rd "Setback": loss of the same developed characteristic in several descent lines.
Similarity: Darwin regards it as one of the classification criteria because there is no absolute direct correlation between branching and divergence.
In some family trees, all branches diverge to the same extent.
Similarity/Mayr: must be determined as a first step, then the genealogy.
Definition similarity: certain characteristics must occur together with other characteristics from which they are logically independent.
Taxonomy: Problem: inconsistent evolution of different groups of characteristics. This can result in completely different classifications. For example, larvae in comparison to adult individuals: can fall into completely different similarity classes.
For example, humans are more molecularly similar to chimpanzees than different species of the genus Drosophila among each other.
Categories/Mayr: there is no reliable definition for the higher categories. Higher taxa can be described very well: e.g. birds or penguins. But the category to which they are assigned to is often subjective._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution.
Das ist Biologie Heidelberg 1998