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Numerical Phenomena: Goal: to avoid any arbitrariness and subjectivity. Up to 100 features that are not weighted. This leads to different classifications when using different feature sets.
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Relevance, >
Classification/Mayr, >
Features/Mayr.
Classification cannot be gradually refined. a) "distance method" b) "thrift method".
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Cladification/Mayr: (c. 1950) is based exclusively on genealogy. Only common derived features (apomorphies), no original features are taken into account. Each taxon consists of a branch of the genealogical tree, which includes the stem species of this branch and all its offspring (including "ex groups," i.e. highly modified offspring). Without any consideration of similarity!
CladismVsSimilarity
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Cladistics, >
Similarity.
Similarity/Darwin/Mayr: Similarity uses as many features as possible.
I 196
Classification/Darwin: shares with the cladification in contrast to the purely numerical phenomenology, that groupings are taken into account.
Taxonomy/Tradition/Darwin: a taxon is monophyletic when all its members descend from the next common ancestor.
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Classification/Mayr.
Taxon/Cladism: "holophyletic", demarcation of the taxa. (Both methods of hierarchies are purely genealogical).
Clade: does not correspond to a taxon in Darwin. A "Cladon" goes back to a root species (and includes it), that is, the kind that has the first apomorphic feature of this branch (Clade).
Cladification: shows well the phylogenetic aspects of the characteristics.
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Phylogenesis.
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VsCladification/Cladism:
1. Most of the clades are very heterogeneous, other stem groups can be much more similar to the stem groups of the sibling groups than daughter groups (end stages).
Klade: does not correspond to a taxon at Darwin. A "Cladon" goes back to a root type (and includes it), that is, the kind that has the first apomorphic feature of this branch (Clade).
Cladification: shows well the phylogenetic aspects of the characteristics.
I 197
VsCladification/Cladism:
1. Most of the clusters are very heterogeneous, other groups can be much more similar to the parent groups of the sibling groups than daughter groups (end stages).
3. The determination to assign sibling groups the same rank is unrealistic. A sibling group, which has hardly developed further, and one who has undergone a drastic evolutionary change (for example, birds) would have to have the same categorical rank.
5. Each population requires to be ranked as a species even if they differ in only one characteristic (phylogenetic species concept).
6. A classification is more useful, the more features it takes into account.
7. Sibling groups are excluded from relationships, even if they are more closely related than remote offspring.
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Classification/Mayr, >
Classification.
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Each classification based on a single characteristic leads to heterogeneous, artificial taxa.
I 199
Multidimensional Order: the order of taxa in a printed line is forcibly one-dimensional.
Cf. >
Lists.
But common lineage is a three-dimensional phenomenon.
1. Derived taxa: behind those from which they are derived.
2. More specialized behind less specialized.
3. Modifications to the original sequence are to be avoided.
