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43-472: The ensatina ( Ensatina eschscholtzii ) is a species complex of plethodontid (lungless) salamanders found in coniferous forests, oak woodland and chaparral from British Columbia , through Washington , Oregon , across California (where all seven subspecies variations are located), all the way down to Baja California in Mexico. The genus Ensatina originated approximately 21.5 million years ago. It

86-537: A ring species in the mountains surrounding the Californian Central Valley . The complex population forms a horseshoe shape around the mountains, and although interbreeding can happen between each of the 19 populations around said horseshoe, the Ensatina eschscholtzii subspecies on the western end of the horseshoe cannot interbreed with the Ensatina klauberi on the eastern end. As such, it

129-710: A common ancestor, but there are exceptions. It may represent an early stage after speciation in which the species were separated for a long time period without evolving morphological differences. Hybrid speciation can be a component in the evolution of a species complex. Species complexes are ubiquitous and are identified by the rigorous study of differences between individual species that uses minute morphological details, tests of reproductive isolation , or DNA -based methods, such as molecular phylogenetics and DNA barcoding . The existence of extremely similar species may cause local and global species diversity to be underestimated. The recognition of similar-but-distinct species

172-530: A host in the case of symbionts or extreme environments). This may constrain possible directions of evolution; in such cases, strongly divergent selection is not to be expected. Also, asexual reproduction, such as through apomixis in plants, may separate lineages without producing a great degree of morphological differentiation. A species complex is usually a group that has one common ancestor (a monophyletic group), but closer examination can sometimes disprove that. For example, yellow-spotted "fire salamanders" in

215-510: A plant should be given a particular infraspecific name can then be decided by comparing it to the type. There is no requirement for a species to be divided into infraspecific taxa, of whatever rank; in other words, a species does not have to have subspecies, varieties, forms, etc. However, if infraspecific ranks are created, then the name of the type of the species must repeat the specific epithet as its infraspecific epithet. The type acquires this name automatically as soon as any infraspecific rank

258-456: A proposed infraspecific name to be legitimate it must be in accordance with all the rules of the ICN. Only some of the main points are described here. A key concept in botanical names is that of a type . In many cases the type will be a particular preserved specimen stored in a herbarium , although there are other kinds of type. Like other names, an infraspecific name is attached to a type. Whether

301-559: A species complex in formation. Nevertheless, similar but distinct species have sometimes been isolated for a long time without evolving differences, a phenomenon known as "morphological stasis". For example, the Amazonian frog Pristimantis ockendeni is actually at least three different species that diverged over 5 million years ago. Stabilizing selection has been invoked as a force maintaining similarity in species complexes, especially when they adapted to special environments (such as

344-496: A species complex. Distinguishing close species within a complex requires the study of often very small differences. Morphological differences may be minute and visible only by the use of adapted methods, such as microscopy . However, distinct species sometimes have no morphological differences. In those cases, other characters, such as in the species' life history , behavior , physiology , and karyology , may be explored. For example, territorial songs are indicative of species in

387-437: A species group usually have partially overlapping ranges but do not interbreed with one another. A Dictionary of Zoology ( Oxford University Press 1999) describes a species group as complex of related species that exist allopatrically and explains that the "grouping can often be supported by experimental crosses in which only certain pairs of species will produce hybrids ." The examples given below may support both uses of

430-413: A sticky milky secretion from the tail. Complex (taxonomy) Two or more taxa that were once considered conspecific (of the same species) may later be subdivided into infraspecific taxa (taxa within a species, such as bacterial strains or plant varieties ), which may be a complex ranking but it is not a species complex. In most cases, a species complex is a monophyletic group of species with

473-490: Is created. As an example, consider Poa secunda J.Presl , whose type specimen is in the Wisconsin State Herbarium. The same epithet can be used again within a species, at whatever level, only if the names with the re-used epithet are attached to the same type. Thus there can be a form called Poa secunda f. juncifolia as well as the subspecies Poa secunda subsp. juncifolia if, and only if,

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516-431: Is important for disease and pest control and in conservation biology although the drawing of dividing lines between species can be inherently difficult . A species complex is typically considered as a group of close, but distinct species. Obviously, the concept is closely tied to the definition of a species. Modern biology understands a species as "separately evolving metapopulation lineage " but acknowledges that

559-479: Is narrower at the base; it is the only subspecies that has such a tail structure, as well as five toes on the hind limbs. Males often have longer tails than the females, and many of these salamanders have lighter-colored limbs, compared to the rest of the body. The adult females lay eggs underground, often in sets of threes, which hatch directly into fully-formed salamanders, skipping the usual aquatic juvenile phase. The subspecies Ensatina eschscholtzii klauberi , or

602-460: Is occurring, which leads to intermediate forms and blurred species boundaries. The informal classification, superspecies, can be exemplified by the grizzled skipper butterfly, which is a superspecies that is further divided into three subspecies. Some authors apply the term to a species with intraspecific variability , which might be a sign of ongoing or incipient speciation . Examples are ring species or species with subspecies , in which it

645-504: Is often unclear if they should be considered separate species. Several terms are used synonymously for a species complex, but some of them may also have slightly different or narrower meanings. In the nomenclature codes of zoology and bacteriology, no taxonomic ranks are defined at the level between subgenus and species, but the botanical code defines four ranks below subgenus (section, subsection, series, and subseries). Different informal taxonomic solutions have been used to indicate

688-453: Is required as there is only one rank below species, the subspecies . The Prokaryotic Code was split from the ICN in 1975. This nomenclature only governs one infraspecific rank, the subspecies, but allows a number of infrasubspecific subdivisions to be used. The authorship is to be specified in the form " Bacillus subtilis subsp. spizizenii Nakamura et al. 1999.", i.e. with only the infraspecific author. The ICN does not regulate

731-400: Is the infraspecific epithet. Names below the rank of species of cultivated kinds of plants and of animals are regulated by different codes of nomenclature and are formed somewhat differently. Article 24 of the ICN describes how infraspecific names are constructed. The order of the three parts of an infraspecific name is: It is customary to italicize all three parts of such a name, but not

774-426: Is the legitimate one and the other must be changed. When indicating authors for infraspecific names, it is possible to show either just the author(s) of the final, infraspecific epithet, or the authors of both the specific and the infraspecific epithets. Examples: In zoological nomenclature , names of taxa below species rank are formed somewhat differently, using a trinomen or 'trinomial name'. No connecting term

817-486: Is thought to be an example of incipient speciation , providing an illustration of "nearly all stages in a speciation process" (Dobzhansky, 1958). Richard Highton , zoologist , argued that Ensatina is a genus of multiple species and not a continuum of one (meaning, by traditional definitions, it is not a ring species). They are generally thought to be found in high elevations, from 520 to 2400m, in conifer forests and oak woodlands. However, populations were discovered along

860-635: Is usually considered as monospecific , being represented by a single species, Ensatina eschscholtzii , with several subspecies forming a ring species. The subspecies Ensatina e. eschscholtzii , the Monterey ensatina, can be found in Santa Cruz and Monterey Counties and into the California coastal mountains . With a head-to-tail length of just between 3–5 in (7.6–12.7 cm), E. e. eschecholtzi can be identified primarily by its tail, which

903-487: The Galápagos Islands described by Charles Darwin . It has been suggested that cryptic species complexes are very common in the marine environment. That suggestion came before the detailed analysis of many systems using DNA sequence data but has been proven to be correct. The increased use of DNA sequence in the investigation of organismal diversity (also called phylogeography and DNA barcoding ) has led to

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946-399: The criteria to delimit species may depend on the group studied. Thus, many traditionally defined species, based only on morphological similarity, have been found to be several distinct species when other criteria, such as genetic differentiation or reproductive isolation , are applied. A more restricted use applies the term to a group of species among which hybridisation has occurred or

989-892: The malaria vector genus of mosquito, Anopheles , the fungi causing cryptococcosis , and sister species of Bactrocera tryoni , or the Queensland fruit fly. That pest is indistinguishable from two sister species except that B. tryoni inflicts widespread, devastating damage to Australian fruit crops, but the sister species do not. When a species is found to be several phylogenetically distinct species, each typically has smaller distribution ranges and population sizes than had been reckoned. The different species can also differ in their ecology, such as by having different breeding strategies or habitat requirements, which must be taken into account for appropriate management. For example, giraffe populations and subspecies differ genetically to such an extent that they may be considered species. Although

1032-471: The treecreepers , a bird genus with few morphological differences. Mating tests are common in some groups such as fungi to confirm the reproductive isolation of two species. Analysis of DNA sequences is becoming increasingly standard for species recognition and may, in many cases, be the only useful method. Different methods are used to analyse such genetic data, such as molecular phylogenetics or DNA barcoding . Such methods have greatly contributed to

1075-410: The Amazonian frog Eleutherodactylus ockendeni is actually at least three different species that diverged over 5 million years ago. A species flock may arise when a species penetrates a new geographical area and diversifies to occupy a variety of ecological niches , a process known as adaptive radiation . The first species flock to be recognized as such was the 13 species of Darwin's finches on

1118-496: The ICN are Cynoglossum cheirifolium β Anchusa ( lanata ) and Polyporus fomentarius β applanatus whilst other examples (coming from the fungus database Index Fungorum ) are Agaricus plexipes b fuliginaria and Peziza capula ß cernua . The ICN allows the possibility that a validly published name could have no defined rank and uses "[unranked]" as the connecting term in such cases. Like specific epithets, infraspecific epithets cannot be used in isolation as names. Thus

1161-399: The ICN, the name of an infraspecific taxon is a combination of the name of a species and an infraspecific epithet , separated by a connecting term that denotes the rank of the taxon. An example of an infraspecific name is Astrophytum myriostigma subvar.  glabrum , the name of a subvariety of the species Astrophytum myriostigma (bishop's hat cactus). In the previous example, glabrum

1204-542: The coast in Volcán Riveroll, a volcanic area located in Baja California. It is thought that they are able to survive in this anomalous region due to the high moisture that comes in from the coast. It is unclear how these populations were able to end up in this coastal region, but it is hypothesized that “the subspecies was once more broadly distributed and became isolated as a result of climate change during

1247-629: The connecting term. For example: The recommended abbreviations for ranks below species are: Although the connecting terms mentioned above are the recommended ones, the ICN allows for other connecting terms in validly published infraspecific taxa. It specifically mentions that Greek letters α, β, γ, etc. can be used in this way in the original document and further ranks may be added without limit. Names that use these connecting terms are now deprecated (though still legal), but they have an importance because they can be basionyms of current species. The commonest cases use "β" and "b"; examples mentioned in

1290-401: The context makes the species clear. The variety cannot be referred to as just macranthum . Sometimes more than three parts will be given; strictly speaking, this is not a name, but a classification . The ICN gives the example of Saxifraga aizoon var. aizoon subvar. brevifolia f. multicaulis subf. surculosa ; the name of the subform would be Saxifraga aizoon subf. surculosa . For

1333-407: The discovery of a great many cryptic species complexes in all habitats. In the marine bryozoan Celleporella hyalina , detailed morphological analyses and mating compatibility tests between the isolates identified by DNA sequence analysis were used to confirm that these groups consisted of more than 10 ecologically distinct species, which had been diverging for many millions of years. Evidence from

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1376-474: The discovery of cryptic species, including such emblematic species as the fly agaric , the water fleas , or the African elephants . Species forming a complex have typically diverged very recently from each other, which sometimes allows the retracing of the process of speciation . Species with differentiated populations, such as ring species , are sometimes seen as an example of early, ongoing speciation:

1419-541: The genus Salamandra , formerly all classified as one species S. salamandra , are not monophyletic: the Corsican fire salamander 's closest relative has been shown to be the entirely black Alpine salamander . In such cases, similarity has arisen from convergent evolution . Hybrid speciation can lead to unclear species boundaries through a process of reticulate evolution , in which species have two parent species as their most recent common ancestors . In such cases,

1462-558: The giraffe, as a whole, is not considered to be threatened, if each cryptic species is considered separately, there is a much higher level of threat. Infraspecific taxa In botany , an infraspecific name is the scientific name for any taxon below the rank of species , i.e. an infraspecific taxon or infraspecies . The scientific names of botanical taxa are regulated by the International Code of Nomenclature for algae, fungi, and plants (ICN). As specified by

1505-539: The hybrid species may have intermediate characters, such as in Heliconius butterflies. Hybrid speciation has been observed in various species complexes, such as insects, fungi, and plants. In plants, hybridization often takes place through polyploidization , and hybrid plant species are called nothospecies . Sources differ on whether or not members of a species group share a range . A source from Iowa State University Department of Agronomy states that members of

1548-424: The identification of cryptic species has led some to conclude that current estimates of global species richness are too low. Pests, species that cause diseases and their vectors, have direct importance for humans. When they are found to be cryptic species complexes, the ecology and the virulence of each of these species need to be re-evaluated to devise appropriate control strategies. Examples are cryptic species in

1591-648: The large-blotched ensatina, can be found along the mountain ranges of Southern California , and south into a small region of the Sierra Juarez in northern Baja California . E. e. klauberi is similar in size to E. e. eschscholtzii ; it is mid-sized, with adults growIng a total length of 3–6 in (7.6–15.2 cm). Females tend to have shorter, wider bodies compared to the males. However, this subspecies differs from E. e. eschscholtzii in its coloration—nearly black, with blotches of orange, tail, and dark eyes. Ensatina eschscholtzii has been described as

1634-471: The late Pleistocene and Holocene.” If this is true, then it is estimated that Ensatina klauberi has been living in this region for thousands of years. Ensatina can usually be found under logs or brush, by or in streams and lakes, and in other moist places. They are easily distressed by improper handling, because they rely on cutaneous respiration , their thin skin is very sensitive to heating, drying and exposure to chemicals from warm hands. They may exude

1677-434: The name of a particular species of Acanthocalycium is Acanthocalycium klimpelianum , which can be abbreviated to A. klimpelianum where the context makes the genus clear. The species cannot be referred to as just klimpelianum . In the same way, the name of a particular variety of Acanthocalycium klimpelianum is Acanthocalycium klimpelianum var. macranthum , which can be abbreviated to A. k. var. macranthum where

1720-408: The names of cultivated plants, of cultivars , i.e. plants specifically created for use in agriculture or horticulture. Such names are regulated by the International Code of Nomenclature for Cultivated Plants (ICNCP). Although logically below the rank of species (and hence "infraspecific"), a cultivar name may be attached to any scientific name at the genus level or below. The minimum requirement

1763-461: The same species. Where closely related species co-exist in sympatry , it is often a particular challenge to understand how the similar species persist without outcompeting each other. Niche partitioning is one mechanism invoked to explain that. Indeed, studies in some species complexes suggest that species divergence have gone in par with ecological differentiation, with species now preferring different microhabitats. Similar methods also found that

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1806-561: The term "species group." Often, such complexes do not become evident until a new species is introduced into the system, which breaks down existing species barriers. An example is the introduction of the Spanish slug in Northern Europe , where interbreeding with the local black slug and red slug , which were traditionally considered clearly separate species that did not interbreed, shows that they may be actually just subspecies of

1849-407: The type specimen of Poa secunda f. juncifolia is the same as the type specimen of Poa secunda subsp. juncifolia (in other words, if there is a single type specimen whose classification is Poa secunda subsp. juncifolia f. juncifolia ). If two infraspecific taxa which have different types are accidentally given the same epithet, then a homonym has been created. The earliest published name

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