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Learn about the comparison between experimental taxonomy and orthodox taxonomy.
Comparison # Experimental Taxonomy:
Aims:
To identify evolutionary units, and by experiment to determine their genetical inter-relationships and the role of the environment in their formation.
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Unit of study:
In non-sexual organisms, the biotype; in sexual organisms, the breading population or large representative sample of it. Material preferably living.
System of Classification:
Classification as such is not a primary aim; where classifications are produced they are intended mainly to present in a systematic fashion data which have been obtained about natural populations. The basic units adopted are diverse, according to immediate purpose and the system in use; e.g. ecotypes, topotypes, convivial.
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Taxonomic structure:
No general system is adopted, but in some groups minor hierarchies have been constructed to reflect the genetical relationships between populations. None of these extends upwards beyond the level at which genetical experimentation becomes impossible.
Source of data:
Inherent in the plants (a) from dead material morphology, anatomy, karyology; (b) from living material observation of complete life cycles; study of physiological behaviour and morphological adaptation in different habitats; genetical tests of interfertility; cytological studies aimed at establishing breeding-systems, etc.
Non-inherent. Geographical distribution, ecology.
Tests of characters:
Observational techniques using statistical methods; experimental techniques using transplanting to test phenotypic variability, and controlled crossings to determine modes of inheritance.
Methods of description:
Based upon population or population samples, using statistical methods. Nomenclatural matters considered of little importance.
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Concept of natural variation involved:
Essentially dynamic:
Full weight is given to the importance of the genetical systems (i.e. breeding behaviour) operative in the groups under study. No rigid “species concept” is accepted or required. The internal variability of sexual populations is recognised, and the adaptative nature of much population differentiation is acknowledged and made a deliberate object of study.
Classification is based upon evolutionary units where these can be recognised and is not committed to a set of formal categories. No general classification of the plant kingdom is attempted.
Comparison # Classical Taxonomy:
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Aims:
To describe all existing “kinds” of plants, to classify them according to their resemblances and differences, and to name them according to a body of internationally agreed rules.
Unit of study:
Individuals or small numbers of individuals, usually dead.
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System of Classification:
Basic unit. The “species,” which is accepted as having objective reality (originally because of the dogma of special creation, and later through the interpretation of evolution as simply another word for “the origin of species”).
Taxonomic structure:
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A hierarchy of categories embracing the whole of the plant kingdom and named according to internationally agreed rules.
Source of data:
Inherent in the plants (a) determinable from dead material : external morphology, later internal morphology (anatomy); (b) from living material: little taken into account except features like periodicity (flowering time, deciduousness, etc.).
Non-inherent. Geographical distribution.
Tests of characters:
Intuition (based on accumulated experience) and trial and error.
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Methods of description:
Based upon individuals and the “type” concept. The giving of names accepted as an important process.
Concept of natural variation involved:
Essentially static:
Assumes continuity of form within species, except for a small amount of “sporting” and variation between individuals. The adaptative significance of differences between plants is not taken into account. The taxonomic hierarchy is accepted as a suitable form of representation of natural variation, and its application in the internationally agreed form is regarded as obligatory in all groups.
Higher units than species are based exclusively upon degrees of morphological resemblance or dissimilarity, although phylogenetic ideas have led to the construction of putative character series intended to show lines of descent.
