“cladistics”的概念、定义、翻译、参考文献-科学参考

cladistics

Biology

A method of classification in which animals and plants are placed into taxonomic groups called clades strictly according to their evolutionary relationships. These relationships are deduced on the basis of certain homologous characters—shared derived traits known as synapomorphies that are thought to indicate common ancestry (see monophyletic). Implicit in this is the assumption that the ancestral line always splits into two descendant lineages, rather than multiple lineages arising at the same point (the latter case is described as an unresolved phylogeny). Also, it requires that truly homologous characters are distinguished from homoplasic features, i.e. ones resulting from convergent evolution (see homoplasy). A diagram indicating these relationships (called a cladogram) therefore consists of a system of dichotomous branches: each point of branching (called a node) represents divergence from a common ancestor, as shown in the diagram. Thus the species A to F form a clade as they share the common ancestor X, and species A to D form a clade of a different taxonomic rank, sharing the ancestor X₂. Species C to F do not form a clade, since the latter must include all the descendants of a common ancestor. Compare phylogram.
Cladistics: a cladogram showing the relationships of six species (A–F)

Geology and Earth Sciences

Special taxonomic system, founded by W. Hennig (1966), and applied to the study of evolutionary relationships. It proposes that common origin can be demonstrated by the shared possession of derived characters, characters in any group being either primitive or derived. In the branching diagrams (cladograms) used to portray these relationships, it is assumed that cladogenesis, or splitting of an evolutionary lineage, always creates two equal daughter taxa: the branching is dichotomous. Thus each pair of daughter taxa constitutes a monophyletic group with a common stem taxon, unique to the group, and a parent taxon always gives rise to two daughter taxa which must be given different names from each other and from the parent, so the parent species ceases to exist. A cladogram is therefore synonymous with a classification. A shortcoming of the method would seem to be that usually it takes no account of the time dimension.

单词	cladistics
释义	cladistics Biology A method of classification in which animals and plants are placed into taxonomic groups called clades strictly according to their evolutionary relationships. These relationships are deduced on the basis of certain homologous characters—shared derived traits known as synapomorphies that are thought to indicate common ancestry (see monophyletic). Implicit in this is the assumption that the ancestral line always splits into two descendant lineages, rather than multiple lineages arising at the same point (the latter case is described as an unresolved phylogeny). Also, it requires that truly homologous characters are distinguished from homoplasic features, i.e. ones resulting from convergent evolution (see homoplasy). A diagram indicating these relationships (called a cladogram) therefore consists of a system of dichotomous branches: each point of branching (called a node) represents divergence from a common ancestor, as shown in the diagram. Thus the species A to F form a clade as they share the common ancestor X, and species A to D form a clade of a different taxonomic rank, sharing the ancestor X₂. Species C to F do not form a clade, since the latter must include all the descendants of a common ancestor. Compare phylogram. Cladistics: a cladogram showing the relationships of six species (A–F) Geology and Earth Sciences Special taxonomic system, founded by W. Hennig (1966), and applied to the study of evolutionary relationships. It proposes that common origin can be demonstrated by the shared possession of derived characters, characters in any group being either primitive or derived. In the branching diagrams (cladograms) used to portray these relationships, it is assumed that cladogenesis, or splitting of an evolutionary lineage, always creates two equal daughter taxa: the branching is dichotomous. Thus each pair of daughter taxa constitutes a monophyletic group with a common stem taxon, unique to the group, and a parent taxon always gives rise to two daughter taxa which must be given different names from each other and from the parent, so the parent species ceases to exist. A cladogram is therefore synonymous with a classification. A shortcoming of the method would seem to be that usually it takes no account of the time dimension.
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