46-515: Sisyrinchium bellum , the western blue-eyed grass or Californian blue-eyed grass , is the common blue-eyed grass of California and Oregon in and west of the Sierra Nevada , its range extending south into Baja California . In parts of its range, western blue-eyed grass has previously been classified as Sisyrinchium eastwoodiae , S. greenei and S. hesperium , but these names are now considered synonyms. Sisyrinchium bellum grows as
92-595: A perennial plant in open places where there is some moisture, particularly grassy areas, though it can also be found in woodlands and at altitudes up to 2,400 metres (7,900 ft). Like other species of blue-eyed grasses that are locally dominant, it is generally known simply as "blue-eyed grass" within its natural range. The stems of Sisyrinchium bellum can grow as long as 60 centimetres (24 in), though they are often shorter. Its leaves are grassy and tufted. The flowers are 1–2 centimetres (0.39–0.79 in) in diameter and purplish-blue, varying somewhat in color from
138-417: A ' grade ', which are fruitless to precisely delineate, especially when including extinct species. Radiation results in the generation of new subclades by bifurcation, but in practice sexual hybridization may blur very closely related groupings. As a hypothesis, a clade can be rejected only if some groupings were explicitly excluded. It may then be found that the excluded group did actually descend from
184-471: A cladistic hypothesis of relationships of taxa whose character states can be observed. Theoretically, a last common ancestor and all its descendants constitute a (minimal) clade. Importantly, all descendants stay in their overarching ancestral clade. For example, if the terms worms or fishes were used within a strict cladistic framework, these terms would include humans. Many of these terms are normally used paraphyletically , outside of cladistics, e.g. as
230-422: A coarse impression of the complexity. A more detailed account will give details about fractions of introgressions between groupings, and even geographic variations thereof. This has been used as an argument for the use of paraphyletic groupings, but typically other reasons are quoted. Horizontal gene transfer is the mobility of genetic info between different organisms that can have immediate or delayed effects for
276-479: A difficulty for taxonomy , where the rank and (genus-)naming of established groupings may turn out to be inconsistent. Cladistics is now the most commonly used method to classify organisms. The original methods used in cladistic analysis and the school of taxonomy derived from the work of the German entomologist Willi Hennig , who referred to it as phylogenetic systematics (also the title of his 1966 book); but
322-489: A large number and variety of different kinds of characters are viewed as more robust than those based on more limited evidence. Mono-, para- and polyphyletic taxa can be understood based on the shape of the tree (as done above), as well as based on their character states. These are compared in the table below. Cladistics, either generally or in specific applications, has been criticized from its beginnings. Decisions as to whether particular character states are homologous ,
368-473: A lot of possible trees. Assigning names to each possible clade may not be prudent. Furthermore, established names are discarded in cladistics, or alternatively carry connotations which may no longer hold, such as when additional groups are found to have emerged in them. Naming changes are the direct result of changes in the recognition of mutual relationships, which often is still in flux, especially for extinct species. Hanging on to older naming and/or connotations
414-457: A period, many branches may have radiated, and it may take hundreds of millions of years for them to have whittled down to just two. Only then one can theoretically assign proper last common ancestors of groupings which do not inadvertently include earlier branches. The process of true cladistic bifurcation can thus take a much more extended time than one is usually aware of. In practice, for recent radiations, cladistically guided findings only give
460-444: A phylogenetic tree are used to justify decisions about character states, which are then used as evidence for the shape of the tree. Phylogenetics uses various forms of parsimony to decide such questions; the conclusions reached often depend on the dataset and the methods. Such is the nature of empirical science, and for this reason, most cladists refer to their cladograms as hypotheses of relationship. Cladograms that are supported by
506-447: A potential piece of evidence for grouping. Synapomorphies (shared, derived character states) are viewed as evidence of grouping, while symplesiomorphies (shared ancestral character states) are not. The outcome of a cladistic analysis is a cladogram – a tree -shaped diagram ( dendrogram ) that is interpreted to represent the best hypothesis of phylogenetic relationships. Although traditionally such cladograms were generated largely on
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#1732797956841552-553: A powerful way to test hypotheses about cross-cultural relationships among folktales. Literature : Cladistic methods have been used in the classification of the surviving manuscripts of the Canterbury Tales , and the manuscripts of the Sanskrit Charaka Samhita . Historical linguistics : Cladistic methods have been used to reconstruct the phylogeny of languages using linguistic features. This
598-400: A precondition of their being synapomorphies, have been challenged as involving circular reasoning and subjective judgements. Of course, the potential unreliability of evidence is a problem for any systematic method, or for that matter, for any empirical scientific endeavor at all. Transformed cladistics arose in the late 1970s in an attempt to resolve some of these problems by removing
644-406: A priori assumptions about phylogeny from cladistic analysis, but it has remained unpopular. The cladistic method does not identify fossil species as actual ancestors of a clade. Instead, fossil taxa are identified as belonging to separate extinct branches. While a fossil species could be the actual ancestor of a clade, there is no way to know that. Therefore, a more conservative hypothesis is that
690-519: A true blue to a definite purple; occasional white-flowering plants are found. It flowers from March to July with a peak in April. Dried in air, its seeds weigh between 1 and 4 mg. After flowering, it dies to the ground and is dormant over the summer. Sisyrinchium bellum prefers some moisture and good drainage, but will tolerate summer dryness. It can be propagated by seed, and it self-sows. It can also be propagated by division of its rhizomes , and
736-565: Is a synapomorphy of the earliest taxa to be included within Tetrapoda: did all the earliest members of the Tetrapoda inherit four limbs from a common ancestor, whereas all other vertebrates did not, or at least not homologously? By contrast, for a group within the tetrapods, such as birds, having four limbs is a plesiomorphy. Using these two terms allows a greater precision in the discussion of homology, in particular allowing clear expression of
782-408: Is an approach to biological classification in which organisms are categorized in groups (" clades ") based on hypotheses of most recent common ancestry . The evidence for hypothesized relationships is typically shared derived characteristics ( synapomorphies ) that are not present in more distant groups and ancestors. However, from an empirical perspective, common ancestors are inferences based on
828-440: Is correct, then the last common ancestor of turtles and birds, at the branch near the ▼ lived earlier than the last common ancestor of lizards and birds, near the ♦ . Most molecular evidence , however, produces cladograms more like this: lizards turtles crocodilians birds If this is accurate, then the last common ancestor of turtles and birds lived later than the last common ancestor of lizards and birds. Since
874-578: Is counter-productive, as they typically do not reflect actual mutual relationships precisely at all. E.g. Archaea, Asgard archaea, protists, slime molds, worms, invertebrata, fishes, reptilia, monkeys, Ardipithecus , Australopithecus , Homo erectus all contain Homo sapiens cladistically, in their sensu lato meaning. For originally extinct stem groups, sensu lato generally means generously keeping previously included groups, which then may come to include even living species. A pruned sensu stricto meaning
920-528: Is no evidence that they recover more "true" or "correct" results from actual empirical data sets Every cladogram is based on a particular dataset analyzed with a particular method. Datasets are tables consisting of molecular , morphological, ethological and/or other characters and a list of operational taxonomic units (OTUs), which may be genes, individuals, populations, species, or larger taxa that are presumed to be monophyletic and therefore to form, all together, one large clade; phylogenetic analysis infers
966-500: Is often adopted instead, but the group would need to be restricted to a single branch on the stem. Other branches then get their own name and level. This is commensurate to the fact that more senior stem branches are in fact closer related to the resulting group than the more basal stem branches; that those stem branches only may have lived for a short time does not affect that assessment in cladistics. The comparisons used to acquire data on which cladograms can be based are not limited to
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#17327979568411012-504: Is similar to the traditional comparative method of historical linguistics, but is more explicit in its use of parsimony and allows much faster analysis of large datasets ( computational phylogenetics ). Textual criticism or stemmatics : Cladistic methods have been used to reconstruct the phylogeny of manuscripts of the same work (and reconstruct the lost original) using distinctive copying errors as apomorphies. This differs from traditional historical-comparative linguistics in enabling
1058-523: The 1990s, the development of effective polymerase chain reaction techniques allowed the application of cladistic methods to biochemical and molecular genetic traits of organisms, vastly expanding the amount of data available for phylogenetics. At the same time, cladistics rapidly became popular in evolutionary biology, because computers made it possible to process large quantities of data about organisms and their characteristics. The cladistic method interprets each shared character state transformation as
1104-672: The Barbary nut iris ( Iris or Moraea sisyrinchium ), and refers to the way the corm tunics resemble a shaggy goat 's-hair coat, sisýra . Authors as early as 1666 give the dubious etymology of Latin sūs "pig" and Greek rhynchos "nose", referring to pigs grubbing the roots. As Goldblatt and Manning explain, "the reason for applying the name to a genus of New World Iridaceae was apparently arbitrary." There are up to 200 species, including: Cladistics Cladistics ( / k l ə ˈ d ɪ s t ɪ k s / klə- DIST -iks ; from Ancient Greek κλάδος kládos 'branch')
1150-685: The South American ones, are not blue, despite the common name. The genus includes species with blue, white, yellow, and purple petals, often with a contrasting centre. Of the species in the United States, the Western Blue-eyed Grass (Sisyrinchium bellum ) is sometimes found with white flowers, while the California Golden-eyed Grass ( Sisyrinchium californicum ) has yellow flowers. The genus
1196-429: The basis of morphological characters and originally calculated by hand, genetic sequencing data and computational phylogenetics are now commonly used in phylogenetic analyses, and the parsimony criterion has been abandoned by many phylogeneticists in favor of more "sophisticated" but less parsimonious evolutionary models of character state transformation. Cladists contend that these models are unjustified because there
1242-531: The branching pattern within that clade. Different datasets and different methods, not to mention violations of the mentioned assumptions, often result in different cladograms. Only scientific investigation can show which is more likely to be correct. Until recently, for example, cladograms like the following have generally been accepted as accurate representations of the ancestral relations among turtles, lizards, crocodilians, and birds: turtles lizards crocodilians birds If this phylogenetic hypothesis
1288-525: The clade, but in principle each level stands on its own, to be assigned a unique name. For a fully bifurcated tree, adding a group to a tree also adds an additional (named) clade, and a new level on that branch. Specifically, also extinct groups are always put on a side-branch, not distinguishing whether an actual ancestor of other groupings was found. The techniques and nomenclature of cladistics have been applied to disciplines other than biology. (See phylogenetic nomenclature .) Cladistics findings are posing
1334-443: The cladograms show two mutually exclusive hypotheses to describe the evolutionary history, at most one of them is correct. The cladogram to the right represents the current universally accepted hypothesis that all primates , including strepsirrhines like the lemurs and lorises , had a common ancestor all of whose descendants are or were primates, and so form a clade; the name Primates is therefore recognized for this clade. Within
1380-402: The development of cultures or artifacts using groups of cultural traits or artifact features. Comparative mythology and folktale use cladistic methods to reconstruct the protoversion of many myths. Mythological phylogenies constructed with mythemes clearly support low horizontal transmissions (borrowings), historical (sometimes Palaeolithic) diffusions and punctuated evolution. They also are
1426-410: The exact historic relationships between the groups. The following terms, coined by Hennig, are used to identify shared or distinct character states among groups: The terms plesiomorphy and apomorphy are relative; their application depends on the position of a group within a tree. For example, when trying to decide whether the tetrapods form a clade, an important question is whether having four limbs
Sisyrinchium bellum - Misplaced Pages Continue
1472-509: The family Iridaceae . Native to the New World , the species are known as blue-eyed grasses. Although they are not true grasses (Poaceae), they are monocots . Several species in the eastern United States are threatened or endangered. This may be due to niche species emerging from their unique tendency toward rapid speciation which helps them adapt to specialized arenic habitats. These are not true grasses , but many species have
1518-512: The field of biology. Any group of individuals or classes that are hypothesized to have a common ancestor, and to which a set of common characteristics may or may not apply, can be compared pairwise. Cladograms can be used to depict the hypothetical descent relationships within groups of items in many different academic realms. The only requirement is that the items have characteristics that can be identified and measured. Anthropology and archaeology : Cladistic methods have been used to reconstruct
1564-401: The flower stems can be rooted. It is moderately hardy and will tolerate temperatures down to 20 °F (−7 °C). The Ohlone used an infusion of the roots and leaves as a cure for indigestion and stomach pain, and similar uses are recorded from other Native American peoples. Blue-eyed grass Sisyrinchium is a large genus of annual to perennial flowering plants in
1610-481: The fossil taxon is related to other fossil and extant taxa, as implied by the pattern of shared apomorphic features. An otherwise extinct group with any extant descendants, is not considered (literally) extinct, and for instance does not have a date of extinction. Anything having to do with biology and sex is complicated and messy, and cladistics is no exception. Many species reproduce sexually, and are capable of interbreeding for millions of years. Worse, during such
1656-468: The general appearance of grasses, as they are low-growing plants with long, thin leaves. They often grow on grasslands . Many species resemble irises , to which they are more closely related. Most species grow as perennial plants , from a rhizome , though some are short-lived (e.g. Sisyrinchium striatum ) , and some are annuals (e.g. Sisyrinchium iridifolium ). The flowers are relatively simple and often grow in clusters. Many species, particularly
1702-407: The hierarchical relationships among different homologous features. It can be difficult to decide whether a character state is in fact the same and thus can be classified as a synapomorphy, which may identify a monophyletic group, or whether it only appears to be the same and is thus a homoplasy, which cannot identify such a group. There is a danger of circular reasoning: assumptions about the shape of
1748-460: The last common ancestor of the group, and thus emerged within the group. ("Evolved from" is misleading, because in cladistics all descendants stay in the ancestral group). To keep only valid clades, upon finding that the group is paraphyletic this way, either such excluded groups should be granted to the clade, or the group should be abolished. Branches down to the divergence to the next significant (e.g. extant) sister are considered stem-groupings of
1794-487: The latter contains Tarsiiformes and Anthropoidea. Lemurs and tarsiers may have looked closely related to humans, in the sense of being close on the evolutionary tree to humans. However, from the perspective of a tarsier, humans and lemurs would have looked close, in the exact same sense. Cladistics forces a neutral perspective, treating all branches (extant or extinct) in the same manner. It also forces one to try to make statements, and honestly take into account findings, about
1840-444: The primates, all anthropoids (monkeys, apes, and humans) are hypothesized to have had a common ancestor all of whose descendants are or were anthropoids, so they form the clade called Anthropoidea. The "prosimians", on the other hand, form a paraphyletic taxon. The name Prosimii is not used in phylogenetic nomenclature , which names only clades; the "prosimians" are instead divided between the clades Strepsirhini and Haplorhini , where
1886-432: The reciprocal host. There are several processes in nature which can cause horizontal gene transfer . This does typically not directly interfere with ancestry of the organism, but can complicate the determination of that ancestry. On another level, one can map the horizontal gene transfer processes, by determining the phylogeny of the individual genes using cladistics. If there is unclarity in mutual relationships, there are
Sisyrinchium bellum - Misplaced Pages Continue
1932-560: The species. Some species, notably Sisyrinchium douglasii , have been transferred to the separate genus Olsynium . The greatest diversity for the genus is found in South America. Approximately one third of the species in the genus have oil producing hairs called elaiophores to attract oil-bees. Nearly all these species are native to South America. Sisyrinchíon is the Greek word, recorded by Pliny and Theophrastus , for
1978-492: The terms "cladistics" and "clade" were popularized by other researchers. Cladistics in the original sense refers to a particular set of methods used in phylogenetic analysis, although it is now sometimes used to refer to the whole field. What is now called the cladistic method appeared as early as 1901 with a work by Peter Chalmers Mitchell for birds and subsequently by Robert John Tillyard (for insects) in 1921, and W. Zimmermann (for plants) in 1943. The term " clade "
2024-419: Was championed at this time by the numerical taxonomists Peter Sneath and Robert Sokal , and evolutionary taxonomy by Ernst Mayr . Originally conceived, if only in essence, by Willi Hennig in a book published in 1950, cladistics did not flourish until its translation into English in 1966 (Lewin 1997). Today, cladistics is the most popular method for inferring phylogenetic trees from morphological data. In
2070-554: Was introduced in 1958 by Julian Huxley after having been coined by Lucien Cuénot in 1940, "cladogenesis" in 1958, "cladistic" by Arthur Cain and Harrison in 1960, "cladist" (for an adherent of Hennig's school) by Ernst Mayr in 1965, and "cladistics" in 1966. Hennig referred to his own approach as "phylogenetic systematics". From the time of his original formulation until the end of the 1970s, cladistics competed as an analytical and philosophical approach to systematics with phenetics and so-called evolutionary taxonomy . Phenetics
2116-409: Was named by Carl Linnaeus in 1753, based on the species Sisyrinchium bermudiana (commonly called Bermudiana ). The taxonomy of this genus is rather perplexing and confusing, as several of these species, such as Sisyrinchium angustifolium , form complexes with many variants named as species. More genetic research and cladistic analysis need to be performed to sort out the relationships between
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