Cladistics (Greek: klados = branch) is a branch of biology that determines the evolutionary relationships between living things based on derived similarity. It is the most prominent of several phylogenetic systematics, which study the evolutionary relationships of living things. Cladistics is a method of rigorous analysis, using "shared derived properties" (synapomorphies: see below) of the organisms being studied. Cladistic analysis forms the basis for most modern systems of biological classification, which seek to grou ...

Including:

• Cladistics - Definitions
• Cladistics - Cladistic methods
• Cladistics - Cladistic classification

Read more here: » Cladistics: Encyclopedia - Cladistics

See also:

Cladistics, Cladistics - Definitions, Cladistics - Cladistic methods, Cladistics - Cladistic classification

Read more here: » Cladistics: Encyclopedia II - Cladistics - Cladistic classification

Typically, a cladistic analysis begins by collecting information on certain features of all the organisms in question. Features may come in different versions (e.g. feather-color may be blue in one species but red in another). These features are collectively called characters, and specific versions are called character states. Thus, "red feathers" and "blue feathers" are two character states of the character "feather-color." After recording several character states, the researcher decides which ones were present befor ...

See also:

Cladistics, Cladistics - Definitions, Cladistics - Cladistic methods, Cladistics - Cladistic classification

Read more here: » Cladistics: Encyclopedia II - Cladistics - Cladistic methods

In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e.g., species, populations). Phylogenetics, also known as phylogenetic systematics, treats a species as a group of lineage-connected individuals over time. Phylogenetic taxonomy, which is an offshoot of, but not a logical consequence of, phylogenetic systematics, constitutes a means of classifying groups of organi ...

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The Class Lycopodiopsida includes the clubmosses. These plants are often loosely grouped as the fern allies. The Lycopodiopsida traditionally included all the clubmosses, including Selaginella and Isoetes. However, subdivisions within the Division Lycopodiophyta are now considered ancient enough to warrant higher-level separation in accordance with cladistics. The clubmosses are thought to be structurally similar to the earliest vascular plants, with small, scale-like leaves, homospo ...

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A clade is group of organisms which share a common ancestor and which includes all descendents of that ancestor. Taxonomy which requires all taxa to be clades is called cladistics. A clade may or may not conform to an existing taxon. A clade is thus a monophyletic group of organisms. The term evolutionary grade is sometimes used for groups of related organisms that don't include all decendents of their common ancestor. The PhyloCode is an attempt at a Code that will allow clades to get a formal name.

A containment hierarchy is a hierarchical collection of strictly nested sets. Each entry in the hierarchy designates a set such that the previous entry is a strict superset, and the next entry is a strict subset. For example, all rectangles are quadrilaterals, but not all quadrilaterals are rectangles, and all squares are rectangles, but not all rectangles are squares. A taxonomy is a classic example of a containment hierarchy: In geometry: shape, polygon, quadrilateral, rectangle, square In biology: anima ...

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Professor David B. Weishampel (born November 16, 1952) is a American palaeontologist in the Department of cell biology and anatomy at Johns Hopkins University School of Medicine. Weishampel received his Ph.D. in Geology from the University of Pennsylvania in 1981. His research focuses include dinosaur systematics, European dinosaurs of the Late Cretaceous, jaw mechanics and herbivory, cladistics and heterochrony and the history of evolutionary biology. Weishampel's most well known published work is The Dinosauria Unive ...

Including:

• David B. Weishampel - Selected publications

Read more here: » David B. Weishampel: Encyclopedia - David B. Weishampel

In biology, a genus (plural genera) is a grouping in the classification of living organisms having one or more related and morphologically similar species. In the common binomial nomenclature, the name of an organism is composed of two parts: its genus (always capitalized) and a species modifier. An example is Homo sapiens, the name for the human species which belongs to the genus Homo. See scientific cla ...

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Cteniogenidae Simoedosauridae Champsosauridae Choristodera is an order of semi-aquatic diapsid reptiles which ranged from the Middle Jurassic, or possibly Late Triassic, to upper Eocene, or upper Oligocene. Choristoderes have been found in North America, Asia, and Europe. The most common fossils are typically found from the Late Cretaceous to the lower Eocene. Cladists have placed them between basal diapsids and basal archosauromorphs but the phylogenetic position of the Choristodera is still uncertain. It has also ...

Including:

• Choristodera - Description/Phylogeny
• Choristodera - Fossil Record

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Ungulates (meaning roughly "hoofed" or "hoofed animal") make up several orders of mammals, of which six to eight survive. There is some dispute as to whether ungulate should be treated as an actual cladistic (evolution-based) group, or merely a phenetic group (similar, but not necessarily related), in light of the fact that all ungulates do not appear to be as closely related as once believed (see below). Ungulates include: Artiodactyla: even-toed ungulates, such as cattle, sheep, goats, pigs, antelope, a ...

Including:

• Ungulate - Relationships
• Ungulate - Recent Developments

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Earthworm is the common reference for the larger members of the Oligochaeta (which is either a class or subclass depending on the author) in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening to the outside of body posterior to the female pores, even though the male segments are anterior to the female. Cladistic studies have supported placing them instead in the Haplotaxida, which also includes the family Haplotaxidae. Folk names for earthworm incl ...

Including:

• Earthworm - Overview
• Earthworm - Anatomy
• Earthworm - Reproduction
• Earthworm - Behavior
• Earthworm - Locomotion and importance to soil
• Earthworm - Benefits
• Earthworm - Earthworms as invasives
• Earthworm - Special habitats
• Earthworm - Ecology
• Earthworm - Threats to earthworms
• Earthworm - Economic Impact
• Earthworm - External References

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Before the general acceptance of 'cladistics' or 'phylogenetic systematics' in paleontology, evolutionary trees were often drawn as the emerging of one group from another. The transitional forms were placed at the borders of these. With the establishment of cladistic methods, relationships are now strictly expressed in so-called cladograms, illustrating the actual branching of the evolutionary lineages. The different so-called 'natural' or 'monophyletic' groups form nested units that do not overlap. Within cladistics there is thus no ...

See also:

Transitional fossil, Transitional fossil - The 'Missing Link', Transitional fossil - Transitional forms and cladistics, Transitional fossil - Transitional forms vs. intermediate forms, Transitional fossil - Misconceptions, Transitional fossil - External link

Read more here: » Transitional fossil: Encyclopedia II - Transitional fossil - Transitional forms and cladistics

In science, parsimony is preference for the least complicated explanation for an observation. This is generally regarded as good when judging hypotheses. Occam's Razor also states the "principle of parsimony". In systematics, maximum parsimony is a cladistic optimality criterion based on the principle of parsimony. Under maximum parsimony, the preferred phylogenetic tree is the tree that requires the ...

See also:

Parsimony, Parsimony - Science, Parsimony - External link

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Molecular systematics has been made possible by the availability of techniques for gene sequencing, which allow the determination of the exact sequence of nucleotides or bases in either DNA or RNA, not necessarily restricted to genes. At present it is still a long and expensive process to sequence the entire DNA of an organism (its genome), and this has been done for only a few species. However it is quite feasible to determine the sequence of a defined area of a particular chromosome. Typical molecular systematic analyses require the ...

See also:

Molecular systematics, Molecular systematics - Theoretical background, Molecular systematics - Example: the phylogeny of the domestic dog, Molecular systematics - Characteristics and assumptions of molecular systematics, Molecular systematics - Reference

Read more here: » Molecular systematics: Encyclopedia II - Molecular systematics - Theoretical background

Molecular systematics has been made possible by the availability of techniques for DNA sequencing, which allow the determination of the exact sequence of nucleotides or bases in either DNA or RNA, not necessarily restricted to genes. At present it is still a long and expensive process to sequence the entire DNA of an organism (its genome), and this has been done for only a few species. However it is quite feasible to determine the sequence of a defined area of a particular chromosome. Typical molecular systematic analyses require the ...

See also:

Molecular systematics, Molecular systematics - Theoretical background, Molecular systematics - Example: the phylogeny of the domestic dog, Molecular systematics - Characteristics and assumptions of molecular systematics, Molecular systematics - Reference

Read more here: » Molecular systematics: Encyclopedia II - Molecular systematics - Theoretical background

This example illustrates several characteristics of molecular systematics and its underlying assumptions. Molecular systematics is an essentially cladistic approach: it assumes that classification must correspond to phylogenetic descent, and that all valid taxa must be at least paraphyletic and preferably monophyletic. Molecular systematics often uses the molecular clock assumption that quantitative similarity of genotype is a sufficient measure of the recency of genetic divergence. Particularly in relation to speciatio ...

See also:

Molecular systematics, Molecular systematics - Theoretical background, Molecular systematics - Example: the phylogeny of the domestic dog, Molecular systematics - Characteristics and assumptions of molecular systematics, Molecular systematics - Reference

Read more here: » Molecular systematics: Encyclopedia II - Molecular systematics - Characteristics and assumptions of molecular systematics

It is commonly stated by anti-evolutionists that there are no known transitional fossils. According to evolutionary scientists, this position is based on a misunderstanding of the nature of what represents a transitional feature. A common creationist argument is that no fossils are found with partially functional features. It is entirely plausible, however, that a complex feature with one function can adapt a wholly different function through evolution. The precursor to e.g. a wing, might originally have only been meant for gliding, trapping flying prey, and/or mating display. Nowadays, wings can still have all of the ...

See also:

Transitional fossil, Transitional fossil - The 'Missing Link', Transitional fossil - Transitional forms and cladistics, Transitional fossil - Transitional forms vs. intermediate forms, Transitional fossil - Misconceptions, Transitional fossil - External link

Read more here: » Transitional fossil: Encyclopedia II - Transitional fossil - Misconceptions

There are three fundamental approaches to textual criticism: copy text editing, eclecticism, and stemmatics. Techniques from the biological discipline of cladistics are now also being used to determine the relationship between manuscripts. Textual criticism - Copy Text Editing. With copy text editing, the textual critic selects a base text from a manuscript thought to be reliable. Often, the base text is selected from the oldest manuscript of the text, but in the early days o ...

See also:

Textual criticism, Textual criticism - Methods of Textual Criticism, Textual criticism - Copy Text Editing, Textual criticism - Eclecticism, Textual criticism - Stemmatics, Textual criticism - Cladistics, Textual criticism - Textual Criticism of the New Testament, Textual criticism - Textual Criticism of Classical Texts

Read more here: » Textual criticism: Encyclopedia II - Textual criticism - Methods of Textual Criticism

For example, Vilà et al (1997) determined haplotypes from a sequence of 261 base pairs in the mitochondrial DNA of 140 domestic dogs, 162 wolves, 5 coyotes, and 10 jackals (of three different species). The dogs were drawn from 67 different pure breeds and 5 cross breeds, and the wolves were drawn from 27 distinct geographically defined populations. The coyotes and jackals were used as the out group. Vilà et al found 27 distinct haplotypes among the wolves, and 26 among the dogs. The wolf haplotypes differed from each other by no mor ...

See also:

Molecular systematics, Molecular systematics - Theoretical background, Molecular systematics - Example: the phylogeny of the domestic dog, Molecular systematics - Characteristics and assumptions of molecular systematics, Molecular systematics - Reference

Read more here: » Molecular systematics: Encyclopedia II - Molecular systematics - Example: the phylogeny of the domestic dog