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Topic: Cladistics


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In the News (Sat 23 Mar 19)

  
  Cladistics - Wikipedia, the free encyclopedia
Cladistics (Greek: klados = branch) is a branch of biology that determines the evolutionary relationships between organisms based on derived similarities.
Thus, cladistic methods can be, and recently have been, usefully applied to non-biological systems, including determining language families in historical linguistics and the filiation of manuscripts in textual criticism.
Stem-based: all descendants of the oldest common ancestor of A and B that is not also an ancestor of Z. Apomorphy-based: the most recent common ancestor of A and B possessing a certain apomorphy (derived character), and all its descendants.
en.wikipedia.org /wiki/Cladistics   (1727 words)

  
 Cladistics - Wikipedia, the free encyclopedia
Cladistics (or phylogenetic systematics) is a branch of biology that seeks to erect classification groups for all organisms, based solely on their evolutionary relationships.
Cladistics has taken a while to settle in, and there is still wide debate over how to apply Henig's ideas in the real world.
Cladistic parsimony is a method of phylogenetic inference in the construction of cladograms.
www.encyclopedia-online.info /Cladistics   (1348 words)

  
 Cladistics - EvoWiki   (Site not responding. Last check: 2007-10-22)
Cladistics is principally concerned with the mapping of cladogenetic evolution—the branching or divergent component of evolution, whereby two lineages arising from shared ancestry, pursue different evolutionary trajectories over time.
Semantics aside, cladistic systematists are primarily occupied with delimiting clades, and this is done on the basis of derived traits, or apomorphies, which are uniquely shared by the members of the putatively holophyletic assemblage, thus becoming synapomorphies.
Cladistics is furthermore not synonymous with systematics or taxonomy, and indeed its goals are far more restricted than either of those broad disciplines (e.g., cladistics does not set out to define or redefine the species concept).
wiki.cotch.net /wiki.phtml?title=Cladistics   (5532 words)

  
 Cladistics Info - Encyclopedia WikiWhat.com   (Site not responding. Last check: 2007-10-22)
Cladistics (or phylogenetic systematics) is a branch of biology that determines the evolutionary relationships between living things based on derived similarity.
Cladistics has taken a while to settle in, and there is some questioning over in just what sort of circumstances cladistics is applicable.
Cladists counter that "significant changes" recognized by evolutionary taxonomists are often too subjective to be a basis for classification.
www.wikiwhat.com /encyclopedia/c/cl/cladistics.html   (1197 words)

  
 What is Cladistics?   (Site not responding. Last check: 2007-10-22)
Cladistics is a method of analyzing the evolutionary relationships between groups to construct their family tree.
Although cladistics is touted as the greatest thing since sliced bread and a totally objective method, it is still no better than the researcher who decides what characters are important to use in the analysis.
The real merit of cladistic methods is in their use of shared derived characters to unite groups and in the ability of the computer to handle large batches of data.
www.fossilnews.com /1996/cladistics.html   (1321 words)

  
 Cladistics
Cladistics takes its name from Hennig's concept of a "clade", which he defined as a group of organisms related by common descent.
Under the basic paradigm of cladistics, the greater the number of synapomorphies between two species or groups, the more recent their common ancestor and the more closely they are related.
Cladistic analysis of these characters has persuaded many (but by no means all) paleontologists that dinosaurs and birds are not merely adjacent sidebranches of reptilian evolution, but that modern birds are actually feathered theropods.
www.elasmo-research.org /education/classification/cladistics.htm   (1205 words)

  
 Critical rationalism: Review of Cladistics book
Cladistics itself is a methodology for classifying and relating both living things and fossils, based strictly on the similarities and differences between them.
What cladistics did do is falsify some of the cherished theories that were common in the study of evolution until the 1980s, maybe even now, and are still reflected in much of the popular idea of evolution today.
Gee explores the application of cladistics to three major problems: the palaeontology of fishes and the ancestry of land-dwelling tetrapods (he himself worked in this field with some of the founders of cladistics as a young researcher); the relationships between birds and dinosaurs and the origin of flight; and human evolution.
www.wisewords.demon.co.uk /popper/p-cladst.html   (664 words)

  
 Cladistics
Cladistics is currently the most popular paradigm of phylogenetic classification in biological taxonomy.
Cladistics would seem at first to be more objective then the linnean and linnean-based systems, simply because in getting rid of higher taxa it also does away of the arbitrariness of whether a higher taxon is, say an order or a class.
Since efficient cladistic computer programs came on the scene, the phylogenies, and the characters on which they are based have become so numerous that the task of comparing in detail the merits of respective phylogenies is now virtually impossible at the level of a general book such as this.
www.kheper.net /evolution/systematics/cladistics.htm   (1704 words)

  
 Clade - Wikipedia, the free encyclopedia
A clade is a term belonging to the discipline of cladistics.
a branch in a cladogram, which is a diagram in the form of a tree resulting from a cladistic analysis.
Strictly speaking, a clade is a scientific hypothesis of evolutionary relationships among the organisms included in the analysis, based on the data considered in a cladistic analysis.
en.wikipedia.org /wiki/Clade   (284 words)

  
 Why Do Biologists Need Cladistics?   (Site not responding. Last check: 2007-10-22)
Today, cladistics is the method of choice for classifying life because it recognizes and employs evolutionary theory.
With cladistics, it is possible to determine whether these stories have merit, or whether they should be abandoned in favor of a competing hypothesis.
The cladistic analysis of these spiders showed that, in fact, orb-weaving was the primitive state, and that cobweb-weaving had evolved from spiders with more orderly webs.
www.holysmoke.org /cretins/clades.htm   (461 words)

  
 Introduction to Cladistics
Cladistics is a particular method of hypothesizing relationships among organisms.
Cladistics is now accepted as the best method available for phylogenetic analysis, for it provides an explicit and testable hypothesis of organismal relationships.
The basic idea behind cladistics is that members of a group share a common evolutionary history, and are "closely related," more so to members of the same group than to other organisms.
www.ucmp.berkeley.edu /clad/clad1.html   (703 words)

  
 What are classification, taxonomy, phylogeny, systematics and cladistics?   (Site not responding. Last check: 2007-10-22)
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.
Unfortunately, the meaning of the word ``cladistics'' is somewhat muddied by the fact that it seems to carry a philosophy with it as well as methodolody.
So, for example, cladists do not accept the old concept of ``reptiles'', since it omits dinosaurs and birds which are descendents of the reptiles as commonly understood.
www.miketaylor.org.uk /dino/faq/s-class/terms   (821 words)

  
 AllRefer.com - cladistics (Biology, General) - Encyclopedia
Cladistics places species in a group, or clade, based on a shared character.
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.
reference.allrefer.com /encyclopedia/C/cladist.html   (287 words)

  
 Phenetics versus Cladistics
Cladistics can be defined as the study of the pathways of evolution.
In other words, cladists are interested in such questions as: how many branches there are among a group of organisms; which branch connects to which other branch; and what is the branching sequence.
While a phenogram may serve as an indicator of cladistic relationships, it is not necessarily identical to the cladogram.
www.icp.ucl.ac.be /~opperd/private/phenetics.html   (677 words)

  
 Teacher Notes for Cladistics Exercise
Cladistics was invented by the German entomologist Hennig in the 1950s, but the basic methods of cladistics were devised in the 19th century by philologists attempting to reconstruct the histories and interrelationships of European languages.
With the rise of cladistics, systematics-- the study of how organisms are classified-- has been transformed from a kind of glorified filing system into an important branch of biological science.
A common cladistic definition of dinosaurs is the last common ancestor of Tyrannosaurus and Triceratops and all of its descendants.
www.geology.wisc.edu /~museum/hughes/cladistics_notes.html   (2860 words)

  
 What is cladistics? How reliable is it?   (Site not responding. Last check: 2007-10-22)
Cladistics is a method of deriving possible family trees, or cladograms, from a set of specimens.
Sophisticated cladistic analysis programs should also allow characters to be weighted by importance, so that (for example) when taxa share the same value for a character x, this can be considered twice as likely to imply that they are related as if they shared the less significant character y.
In other words, the primary benefit to cladistic analysis may not be that the results are ``better'' so much as that systematists have to ``show their working'', which makes it much easier for others to improve upon it in the future.
www.miketaylor.org.uk /dino/faq/s-class/clad   (1863 words)

  
 BBC - h2g2 - Cladistics
Cladistics abandons this convention almost entirely, since such a structured hierarchy of taxa is simply not realistic when focusing on relationships.
Cladistics is quite complex and cladograms are subject to frequent changes as new evidence turns up.
The battle continues, and although it would be nice if cladistics were universally adopted as the sole method for classifying organisms, this is unlikely to happen for many years to come.
www.bbc.co.uk /dna/h2g2/A517141   (2138 words)

  
 Cladistics - Psychology Central   (Site not responding. Last check: 2007-10-22)
Image:Cladogram-example1.png Cladistics (Greek: klados = branch) is a branch of biology that determines the evolutionary relationships between organisms based on derived similarities.
It is the most prominent of several phylogenetic systematics, which study the evolutionary relationships between organisms.
The adjectives plesiomorphic and apomorphic are used instead of "primitive" and "advanced" to avoid placing value-judgements on the evolution of the character states, since both may be advantageous in different circumstances.
psychcentral.com /psypsych/Cladistics   (1798 words)

  
 Cladistics
Cladistics doesn't assume any particular theory of evolution, only the background knowledge of descent with modification.
Thus, cladistic methods can be, and has recently been, usefully applied to non-biological systems, including determining language families in historical linguistics and the filiation of manuscripts in textual criticism.
A formal code of phylogenetic nomenclature, the Phylocode[1] (http://www.ohiou.edu/phylocode/), is currently under development for a cladistic taxonomy that abandons the Linnaean structure.
www.wordlookup.net /cl/cladistics.html   (1200 words)

  
 Lecture 6 - Cladistics
In cladistics we look for characters that we can hypothesis are shared because they were inherited from a common ancestor.
Cladistics was basically invented by Willi Hennig who was a specialist in flies.
The method in cladistics is to build and test relationships based on the distribution of the states of characters and to build groups by the recognition of synapomorphies.
www.ldeo.columbia.edu /edu/dees/courses/v1001/cladistics5.html   (903 words)

  
 Taxonomic Classification and Phylogenetic Trees   (Site not responding. Last check: 2007-10-22)
The basic assumption behind cladistics is that members of a group share a common evolutionary history, and are thus more "closely related" to one another than they are to other groups of organisms.
Thus in cladistics, the emphasis is not upon the presence of all shared traits, but upon the presence of shared derived (apomorphic) traits.
A cladist would insist that these "sister groups" be placed in the same taxon, even though the amount of change from the common ancestor is much greater for the birds than it is for the crocodiles.
www.mhhe.com /biosci/pae/zoology/cladogram   (2162 words)

  
 Cladistics
Cladistics - also called Phylogenetic Systematics or Phylogenetic Taxonomy - is a method of classifying organisms by common ancestry, based on the branching of the evolutionary family tree.
Cladistic methodology can even be used to predict properties of yet-to-be discovered organisms.
This is based on the fact that cladists seem to assume it is enough simply to know all the characteristics of the representative members of a group in order to work out their precise phylogenetic relationships.
www.palaeos.com /Systematics/Cladistics/cladistics.htm   (1667 words)

  
 Science: Cladistics and Early Hominid Phylogeny@ HighBeam Research   (Site not responding. Last check: 2007-10-22)
301) (1, 2) are skeptical about the utility of cladistic analysis to resolve questions about early hominid phylogeny.
Although we disagree with aspects of these studies (3, 4), it is true that phylogenetic analyses would benefit from studies of character variability and integration.
Cladistics is the most objective method available for generating and testing hypotheses about phylogeny.
www.highbeam.com /library/doc0.asp?DOCID=1P1:29322534&refid=ip_encyclopedia_hf   (194 words)

  
 Cladistic Literature
Experimental cladistic analysis of anatomically preserved arborescent lycopsids from the Carboniferous of Euramerica: An essay in paleobotanical phylogenetics.
Coddington, J. Cladistics and spider classification: Araneomorph phylogeny and the monophyly of orbweavers (Araneae: Araneomorphae; Orbiculariae).
Cladistical analysis of G-banded chromosomes of nectar feeding bats (Glossophaginae: Phyllostomidae).
ag.arizona.edu /systbiol/SSBWeb/info/cladliterature.html   (10262 words)

  
 Nearctica - Evolution - Systematics and Phylogeny
An excellent series of lecture notes on all aspects of systematics including a brief history of systematics, speciation, classification, cladistic methods, phenetic methods, character evidence, nomenclature, and applications of systematics to evolution and biodiversity.
An introduction to the principles of cladistics (phylogenetic systematics).
The manual is in the form of an Adobe Acrobat document (pdf) and covers most of the major topics in cladistics including both philosophy and methodology.
www.nearctica.com /evolve/taxonomy.htm   (785 words)

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