23-557: June Lake can refer to: Canada [ edit ] June Lake (Mackenzie Mountains) , a lake in the Sekwi Range, Canada and site of several Elliptocephala species June Lake (Vancouver Island) , a lake on British Columbia's Vancouver Island, Canada United States [ edit ] June Lake (Sharp County, Arkansas) , a lake in Sharp County, Arkansas June Lake, California ,
46-581: A monophyletic group or natural group , is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree . In the taxonomical literature, sometimes the Latin form cladus (plural cladi ) is used rather than the English form. Clades are the fundamental unit of cladistics , a modern approach to taxonomy adopted by most biological fields. The common ancestor may be an individual,
69-588: A population , or a species ( extinct or extant ). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over the last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic . Some of
92-479: A "ladder", with supposedly more "advanced" organisms at the top. Taxonomists have increasingly worked to make the taxonomic system reflect evolution. When it comes to naming , this principle is not always compatible with the traditional rank-based nomenclature (in which only taxa associated with a rank can be named) because not enough ranks exist to name a long series of nested clades. For these and other reasons, phylogenetic nomenclature has been developed; it
115-446: A branch of mammals that split off after the end of the period when the clade Dinosauria stopped being the dominant terrestrial vertebrates 66 million years ago. The original population and all its descendants are a clade. The rodent clade corresponds to the order Rodentia, and insects to the class Insecta. These clades include smaller clades, such as chipmunk or ant , each of which consists of even smaller clades. The clade "rodent"
138-623: A clade can be described based on two different reference points, crown age and stem age. The crown age of a clade refers to the age of the most recent common ancestor of all of the species in the clade. The stem age of a clade refers to the time that the ancestral lineage of the clade diverged from its sister clade. A clade's stem age is either the same as or older than its crown age. Ages of clades cannot be directly observed. They are inferred, either from stratigraphy of fossils , or from molecular clock estimates. Viruses , and particularly RNA viruses form clades. These are useful in tracking
161-419: A node at the midline. The third thorax segment from the front (T3) is not larger than the neighboring segments and does not carry larger spines. Thoracic pleural furrows extend onto spines. Long backward directed spine on the midline of T15, and this spine is broad at its base. Clade In biological phylogenetics , a clade (from Ancient Greek κλάδος (kládos) 'branch'), also known as
184-422: A revised taxonomy based on a concept strongly resembling clades, although the term clade itself would not be coined until 1957 by his grandson, Julian Huxley . German biologist Emil Hans Willi Hennig (1913–1976) is considered to be the founder of cladistics . He proposed a classification system that represented repeated branchings of the family tree, as opposed to the previous systems, which put organisms on
207-429: A suffix added should be e.g. "dracohortian". A clade is by definition monophyletic , meaning that it contains one ancestor which can be an organism, a population, or a species and all its descendants. The ancestor can be known or unknown; any and all members of a clade can be extant or extinct. The science that tries to reconstruct phylogenetic trees and thus discover clades is called phylogenetics or cladistics ,
230-589: A trilobite genus of the Ptychopariida order. The species E. walcotti was named in honor of Charles Doolittle Walcott , a renowned early paleontologist, that described many trilobite species. According to Lieberman E. sequomalus is an early species, close to the common ancestor of the genus. The rest of the species fall into two distinct groups. The first consists of the closely related E. bicensis and E. asaphoides , with E. walcotti and twin species E. praenuntius slightly less close and E. mediocris near
253-944: A village in Mono County, U.S. June Lake (California) , a lake next to the village, U.S. June Lake (Washington) , a lake in the Alpine Lakes Wilderness , Washington, U.S. June Lake, lakes in Wisconsin in Iron County and Lincoln County June Lake, a lake in Marinette County, Wisconsin Other uses [ edit ] June Lake, a character in the 1938 American Western film The Frontiersmen See also [ edit ] June Lake Junction, California , an unincorporated community in Mono County Topics referred to by
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#1732851955487276-508: Is different from Wikidata All article disambiguation pages All disambiguation pages Elliptocephala Elliptocephala is an extinct genus from a well-known class of fossil marine arthropods , the trilobites . It lived from the later part of the Tommotian ( upper Schmidtiellus mickwitzi -zone ) to the upper Botomian ( early middle Olenellus -zone ). Elliptocephala can easily be confused with Ellipsocephalus ,
299-471: Is in turn included in the mammal, vertebrate and animal clades. The idea of a clade did not exist in pre- Darwinian Linnaean taxonomy , which was based by necessity only on internal or external morphological similarities between organisms. Many of the better known animal groups in Linnaeus's original Systema Naturae (mostly vertebrate groups) do represent clades. The phenomenon of convergent evolution
322-515: Is responsible for many cases of misleading similarities in the morphology of groups that evolved from different lineages. With the increasing realization in the first half of the 19th century that species had changed and split through the ages, classification increasingly came to be seen as branches on the evolutionary tree of life . The publication of Darwin's theory of evolution in 1859 gave this view increasing weight. In 1876 Thomas Henry Huxley , an early advocate of evolutionary theory, proposed
345-489: Is still controversial. As an example, see the full current classification of Anas platyrhynchos (the mallard duck) with 40 clades from Eukaryota down by following this Wikispecies link and clicking on "Expand". The name of a clade is conventionally a plural, where the singular refers to each member individually. A unique exception is the reptile clade Dracohors , which was made by haplology from Latin "draco" and "cohors", i.e. "the dragon cohort "; its form with
368-676: The Biceratopsinae and the Bristoliinae . Including Elliptocephala , this clade is the sistergroup of the Olenellidae . As with most early trilobites, Elliptocephala has an almost flat exoskeleton, that is only thinly calcified, and has crescent-shaped eye ridges. As part of the Olenellina suborder, Elliptocephala lacks dorsal sutures. Like all other members of the Olenelloidea superfamily,
391-420: The backward ring-shaped lobe (also called occipital ring or L0) and the most backward set of side lobes (L1) taken together, measured along the midline (or sagittally). L4 is also much wider than L0. Side lobes L2 and L3 do not merge with each other. The line between the backward tip of eye lobe and the junction of the back margin of lobe with glabella with the midline is 10-20°. L3 touches the eye ridge. L0 carries
414-462: The basis of this group. The second group consisting of the closely related E. mirabilis and E. lundgreni , with E. logani and E. parvifrons slightly further removed, followed by E. paraoculus , and E. laxocules near the basis of this second group. Elliptocephala is the sistergroup of the clade comprising Wanneria walcottana , the Holmiidae , Fritzolenellus , Mummaspis , Laudonia ,
437-408: The eye-ridges spring from the back of the frontal lobe (L4) of the central area of the cephalon, that is called glabella . The head shield (or cephalon) of Ellipticephala carries backwards directed spines at the corner between the halfcircle shaped frontal and side margin and the backmargin that is roughly perpendicular to the midline. The frontal lobe of the glabella (L4) is roughly 1½× the length of
460-518: The latter term coined by Ernst Mayr (1965), derived from "clade". The results of phylogenetic/cladistic analyses are tree-shaped diagrams called cladograms ; they, and all their branches, are phylogenetic hypotheses. Three methods of defining clades are featured in phylogenetic nomenclature : node-, stem-, and apomorphy-based (see Phylogenetic nomenclature§Phylogenetic definitions of clade names for detailed definitions). The relationship between clades can be described in several ways: The age of
483-482: The relationships between organisms that the molecular biology arm of cladistics has revealed include that fungi are closer relatives to animals than they are to plants, archaea are now considered different from bacteria , and multicellular organisms may have evolved from archaea. The term "clade" is also used with a similar meaning in other fields besides biology, such as historical linguistics ; see Cladistics § In disciplines other than biology . The term "clade"
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#1732851955487506-453: The same term [REDACTED] This disambiguation page lists articles associated with the title June Lake . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=June_Lake&oldid=905868139 " Categories : Disambiguation pages Place name disambiguation pages Hidden categories: Short description
529-423: Was coined in 1957 by the biologist Julian Huxley to refer to the result of cladogenesis , the evolutionary splitting of a parent species into two distinct species, a concept Huxley borrowed from Bernhard Rensch . Many commonly named groups – rodents and insects , for example – are clades because, in each case, the group consists of a common ancestor with all its descendant branches. Rodents, for example, are
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