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Cladistics
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Cladistics is the method of choice for systematic classification and comparative studies in all fields of biology. In cladistics, reconstructed genealogies are based on common ancestry rather than on simple anatomical similarity and therefore effectively reveal true phylogenetic relationships. Now available in paperback, this excellent introduction to cladistics is based on the popular training course originally offered by the Systematics Association. The book surveys a wide range of topics, including the principle of parsimony, character coding and cladistic tree-building methods, tree statistics, and methods for determining character polarity. Alternatives to parsimony, molecular applications of cladistics, and the relevance of fossils are ... discussed in detail. Concluding chapters review two critical topics of contemporary concern: cladistic biogeography and the implementation of cladistic results in systematics.
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Cladistics and phylogenetic reconstruction are subjects which biology students find quite difficult to grasp when taught from conventional textbooks. This CD provides students with a complete self-study introductory course in phylogenetic reconstruction using cladistic analysis. The CD is fully interactive and includes animated sequences, questions at the end of each section, and practical exercises. It is the first exclusively pedagogical CD-ROM devoted to this topic. By the end of the course students should have a basic understanding of cladistics and be able to reconstruct phylogenetic relationships from morphological and molecular data. The CD-ROM is accompanied by a short textbook.
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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 paleontology the characters are necessarily skeletal.
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Cladistics... known as [P]hylogenetic systematics, is a relatively new way of doing systematics. It works by analysing different taxa to find objective similarities and differences between them, and using those similarities and differences to derive a hierarchical structure showing which taxa are most similar to others. The assumption is that similar taxa are similar because they are related, so that the trees produced by cladistic analysis are approximations to the phylogeny of the group being studied. The cladistic method was first described in 1966 by Hennig, but has really taken off on the last decade due to the availability of cheap, powerful computers to run the analyses.
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"Cladistics is defined in this work as a 'method of systematic classification that aims to reconstruct genealogies based on common ancestry... revealing the phylogenetic relationships between taxa'. Cladistics is the method of choice for comparative studies in the construction of cladograms and consensus trees. Three-item statements, another method of representing relationships, is also discussed. The text will be of interest to students, teachers, and researchers. Cladograms and consensus tree supplement the text."--
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Cladistics was introduced by the German entomologist Willi Hennig, who put forward his ideas in 1950. He wrote in his native language, so these were completely ignored until 1966 when an English translation of a manuscript was published under the title “Phylogenetic Systematics” (Hennig 1966). It is not an easy book to read but fortunately many others have been written that have both fl eshed out and distorted his ideas. Hennig’s most important contribution was to offer a precise defi nition of biological relationship and to suggest how that relationship might be discovered.
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Cladistics