| 单词 | cladistics | |||
| 释义 | cladisticscla·dis·ticsC0380800 (klə-dĭs′tĭks)cladistics(kləˈdɪstɪks)cla•dis•tics(kləˈdɪs tɪks)n. (used with a pl. v.)
cladisticscladistics(klədĭs`tĭks) orphylogenetic systematics(fī'lōjənĕt`ĭk), an approach to the classificationclassification,in biology, the systematic categorization of organisms into a coherent scheme. The original purpose of biological classification, or systematics, was to organize the vast number of known plants and animals into categories that could be named, remembered, and ..... Click the link for more information. of living things in which organisms are defined and grouped by the possession of one or more shared characteristics (called characters) that are derived from a common ancestor and that were not present in any ancestral group (as envisioned by Charles DarwinDarwin, Charles Robert, 1809–82, English naturalist, b. Shrewsbury; grandson of Erasmus Darwin and of Josiah Wedgwood. He firmly established the theory of organic evolution known as Darwinism. ..... Click the link for more information. 's idea of "descent with modification"). Developed by Willi Hennig, a German entomologist, in the 1950s, it is a method of reconstructing evolutionary relationships that emphasizes the importance of descent and common ancestry rather than chronology. Cladistics places species in a group, or clade, based on a shared character. Within a clade, species that share other characters unique to them are grouped together, and so on, until a cladogram (a branching diagram that resembles a family tree) is assembled. For example, all vertebrates make up a clade; all tetrapods (vertebrates that have four limbs with wrists, ankles, toes, and fingers) form their own clade within the vertebrate clade. In this example the vertebrate clade would be considered "primitive" and the tetrapod clade "derived" or "advanced." In living creatures genetic characters or behaviors as well as more obvious anatomical features might be considered in assembling a cladogram. In paleontologypaleontology Cladistics is especially significant in paleontology, as it points out gaps in the fossil evidence. It is also felt to be more objective than fossil study, which of necessity extrapolates from a limited number of finds that may or may not be representative of the whole. See also fossilfossil, cladisticscladisticscladistics(klə-dĭs′tĭks)cladisticsan approach to CLASSIFICATION by which organisms are ordered and ranked entirely on a basis which reflects recent origin from a common ancestor, i.e. like a family tree. The system is concerned simply with the branching of the tree and not with the degree of difference. The latter is the concern of evolutionary taxonomists who oppose the cladistic approach.cladistics
Synonyms for cladistics
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