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90-477: Acanthomintha duttonii is a species of annual plant endemic to San Mateo County, California in the family Lamiaceae . It is commonly called San Mateo thornmint and is found growing on serpentine soils near the Crystal Springs Reservoir in a six-mile (10 km) long strip on the east side of Montara Mountain at elevations of approximately 150 to 300 meters. The species

180-423: A mutation–selection balance . It is predicted that a viral quasispecies at a low but evolutionarily neutral and highly connected (that is, flat) region in the fitness landscape will outcompete a quasispecies located at a higher but narrower fitness peak in which the surrounding mutants are unfit, "the quasispecies effect" or the "survival of the flattest". There is no suggestion that a viral quasispecies resembles

270-400: A "classical" method of determining species, such as with Linnaeus, early in evolutionary theory. However, different phenotypes are not necessarily different species (e.g. a four-winged Drosophila born to a two-winged mother is not a different species). Species named in this manner are called morphospecies . In the 1970s, Robert R. Sokal , Theodore J. Crovello and Peter Sneath proposed

360-424: A 'smallest clade' idea" (a phylogenetic species concept). Mishler and Wilkins and others concur with this approach, even though this would raise difficulties in biological nomenclature. Wilkins cited the ichthyologist Charles Tate Regan 's early 20th century remark that "a species is whatever a suitably qualified biologist chooses to call a species". Wilkins noted that the philosopher Philip Kitcher called this

450-428: A connected series of neighbouring populations, each of which can sexually interbreed with adjacent related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene flow between each "linked" population. Such non-breeding, though genetically connected, "end" populations may co-exist in the same region thus closing

540-432: A different species from its ancestors. Viruses have enormous populations, are doubtfully living since they consist of little more than a string of DNA or RNA in a protein coat, and mutate rapidly. All of these factors make conventional species concepts largely inapplicable. A viral quasispecies is a group of genotypes related by similar mutations, competing within a highly mutagenic environment, and hence governed by

630-508: A genetic boundary suitable for defining a species concept is present. DNA barcoding has been proposed as a way to distinguish species suitable even for non-specialists to use. One of the barcodes is a region of mitochondrial DNA within the gene for cytochrome c oxidase . A database, Barcode of Life Data System , contains DNA barcode sequences from over 190,000 species. However, scientists such as Rob DeSalle have expressed concern that classical taxonomy and DNA barcoding, which they consider

720-465: A lineage should be divided into multiple chronospecies , or when populations have diverged to have enough distinct character states to be described as cladistic species. Species and higher taxa were seen from the time of Aristotle until the 18th century as categories that could be arranged in a hierarchy, the great chain of being . In the 19th century, biologists grasped that species could evolve given sufficient time. Charles Darwin 's 1859 book On

810-597: A low calcium - magnesium ratio, lack of essential nutrients namely nitrogen , potassium , and phosphorus , and high concentrations of heavy metals . Many species that have evolved to grow on serpentine soils have are not adapted to compete with other plants and do not survive well under competition in other soils that tend to have denser plant numbers; in serpentine soils plant densities are lower resulting in less direct competition for resources like light and water. This rare annual species of wildflower has populations that fluctuates yearly with recorded population ranges in

900-402: A low calcium-to-magnesium ratio and have low levels of many essential nutrients such as nitrogen (N), phosphorus (P), and potassium (K). Serpentine soils contain high concentrations of heavy metals, including chromium, iron, cobalt, and nickel. Together, these factors create serious ecological challenges for plants living in serpentine soils. Serpentinite is a meta-igneous rock formed by

990-492: A misnomer, need to be reconciled, as they delimit species differently. Genetic introgression mediated by endosymbionts and other vectors can further make barcodes ineffective in the identification of species. A phylogenetic or cladistic species is "the smallest aggregation of populations (sexual) or lineages (asexual) diagnosable by a unique combination of character states in comparable individuals (semaphoronts)". The empirical basis – observed character states – provides

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1080-449: A particular species, including which genus (and higher taxa) it is placed in, is a hypothesis about the evolutionary relationships and distinguishability of that group of organisms. As further information comes to hand, the hypothesis may be corroborated or refuted. Sometimes, especially in the past when communication was more difficult, taxonomists working in isolation have given two distinct names to individual organisms later identified as

1170-400: A perfect model of life, it is still a useful tool to scientists and conservationists for studying life on Earth, regardless of the theoretical difficulties. If species were fixed and clearly distinct from one another, there would be no problem, but evolutionary processes cause species to change. This obliges taxonomists to decide, for example, when enough change has occurred to declare that

1260-400: A short way of saying that something applies to many species within a genus, but not to all. If scientists mean that something applies to all species within a genus, they use the genus name without the specific name or epithet. The names of genera and species are usually printed in italics . However, abbreviations such as "sp." should not be italicised. When a species' identity is not clear,

1350-604: A six-mile-long (10 km) fragmented strip that includes the Edgewood colony. This species is only known to grow on serpentine soils in grassland communities that are generally species-rich for serpentine soils; the area they are growing in on the San Francisco Peninsula also contains sloping chaparral . Other native species that grow in the same area include Nassella pulchra , Delphinium hesperium , and Hemizonia congesta var. luzulifolia , plus

1440-404: A specialist may use "cf." before the epithet to indicate that confirmation is required. The abbreviations "nr." (near) or "aff." (affine) may be used when the identity is unclear but when the species appears to be similar to the species mentioned after. With the rise of online databases, codes have been devised to provide identifiers for species that are already defined, including: The naming of

1530-523: A species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups. It has been argued that this definition is a natural consequence of the effect of sexual reproduction on the dynamics of natural selection. Mayr's use of the adjective "potentially" has been a point of debate; some interpretations exclude unusual or artificial matings that occur only in captivity, or that involve animals capable of mating but that do not normally do so in

1620-400: A species as determined by a taxonomist. A typological species is a group of organisms in which individuals conform to certain fixed properties (a type), so that even pre-literate people often recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens (such as longer or shorter tails) would differentiate the species. This method was used as

1710-491: A species. All species definitions assume that an organism acquires its genes from one or two parents very like the "daughter" organism, but that is not what happens in HGT. There is strong evidence of HGT between very dissimilar groups of prokaryotes , and at least occasionally between dissimilar groups of eukaryotes , including some crustaceans and echinoderms . The evolutionary biologist James Mallet concludes that there

1800-685: A species. Generally the term includes the unknown element of a distinct act of creation. Many authors have argued that a simple textbook definition, following Mayr's concept, works well for most multi-celled organisms , but breaks down in several situations: Species identification is made difficult by discordance between molecular and morphological investigations; these can be categorised as two types: (i) one morphology, multiple lineages (e.g. morphological convergence , cryptic species ) and (ii) one lineage, multiple morphologies (e.g. phenotypic plasticity , multiple life-cycle stages). In addition, horizontal gene transfer (HGT) makes it difficult to define

1890-528: A taxonomic decision at the discretion of cognizant specialists, is not governed by the Codes of Zoological or Botanical Nomenclature, in contrast to the PhyloCode , and contrary to what is done in several other fields, in which the definitions of technical terms, like geochronological units and geopolitical entities, are explicitly delimited. The nomenclatural codes that guide the naming of species, including

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1980-517: A traditional biological species. The International Committee on Taxonomy of Viruses has since 1962 developed a universal taxonomic scheme for viruses; this has stabilised viral taxonomy. Most modern textbooks make use of Ernst Mayr 's 1942 definition, known as the Biological Species Concept as a basis for further discussion on the definition of species. It is also called a reproductive or isolation concept. This defines

2070-455: A tube with five sepals and the stamens enclosed within the zygomorphic corolla. The bracts in the inflorescence have marginal spines, thus the basis of the common name 'thornmints'. All Acanthomintha have the upper three lobes of its calyx acuminate and the lower two lobes oblong in shape; furthermore, all Acanthomintha corollae are funnel shaped and white with occasional tinting of purple. Each Acanthomintha species has four stamens, with

2160-637: A unique ecoregion found in parts of the United States in small but widely distributed areas of the Appalachian Mountains and the Coast Ranges of California , Oregon , and Washington. Species-rich archipelagos of communities comprise 1.5% of the state's land area. In California, 10% of the state's plants are serpentine endemics. The barrens occur on outcrops of altered ultramafic ophiolites . They are named for minerals of

2250-447: A variation on the morphological species concept, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms. It differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species

2340-515: A variety of reasons. Viruses are a special case, driven by a balance of mutation and selection , and can be treated as quasispecies . Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics . Early taxonomists such as Linnaeus had no option but to describe what they saw: this was later formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts,

2430-613: Is "Southern Blue Ridge Ultramafic Outcrop Barren" and believed to be unique to the Buck Creek area. In 1995, the United States Forest Service began active conservation management of the site, primarily with prescribed controlled burns , which, along with some manual cover removal, has been successful in regenerating populations of previously sparse species. In addition to over 20 conservationally listed plant species, Rhiannon’s aster ( Symphyotrichum rhiannon )

2520-438: Is "an entity composed of organisms which maintains its identity from other such entities through time and over space, and which has its own independent evolutionary fate and historical tendencies". This differs from the biological species concept in embodying persistence over time. Wiley and Mayden stated that they see the evolutionary species concept as "identical" to Willi Hennig 's species-as-lineages concept, and asserted that

2610-499: Is a 176-acre (71 ha) property conserved by the Lancaster County Conservancy that is a prime example of a serpentine barren. It was originally a grassland, but wildfire suppression led to the conversion of the area to forest. This barren contains the rare serpentine aster ( Symphyotrichum depauperatum ), as well as a number of rare species of moths and skippers . In Chester County, Pennsylvania ,

2700-400: Is a group of sexually reproducing organisms that recognise one another as potential mates. Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms; no matter whether populations can hybridise successfully, they are still distinct cohesion species if

2790-530: Is a hyper-accumulator of nickel and Sedum laxum expresses succulence . In some cases, symbioses with serpentine tolerant ectomycorrhizal help facilitate plants’ adaptation to edaphic stressors on serpentine. Adaptation to serpentine soils has evolved multiple times. Serpentine-tolerant plants are evolutionarily younger than non-serpentine plants. The heterogeneity of serpentine communities coupled with their patchy distribution limits gene flow but promotes speciation and diversification. Habitat heterogeneity

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2880-458: Is a set of organisms adapted to a particular set of resources, called a niche, in the environment. According to this concept, populations form the discrete phenetic clusters that we recognise as species because the ecological and evolutionary processes controlling how resources are divided up tend to produce those clusters. A genetic species as defined by Robert Baker and Robert Bradley is a set of genetically isolated interbreeding populations. This

2970-425: Is an important contributor to the level of endemism and biodiversity in this system. Although the patchy distribution is attributed to the high rates of speciation in serpentine communities, there are a number of challenges associated with this. The spatial isolation from source and other populations limit gene flow , which could make these populations vulnerable to changing environmental conditions. In addition, there

3060-414: Is called speciation . Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book The Origin of Species . Speciation depends on a measure of reproductive isolation , a reduced gene flow. This occurs most easily in allopatric speciation, where populations are separated geographically and can diverge gradually as mutations accumulate. Reproductive isolation

3150-412: Is called the specific name or the specific epithet (in botanical nomenclature , also sometimes in zoological nomenclature ). For example, Boa constrictor is one of the species of the genus Boa , with constrictor being the species' epithet. While the definitions given above may seem adequate at first glance, when looked at more closely they represent problematic species concepts. For example,

3240-403: Is described formally, in a publication that assigns it a unique scientific name. The description typically provides means for identifying the new species, which may not be based solely on morphology (see cryptic species ), differentiating it from other previously described and related or confusable species and provides a validly published name (in botany) or an available name (in zoology) when

3330-671: Is further weakened by the existence of microspecies , groups of organisms, including many plants, with very little genetic variability, usually forming species aggregates . For example, the dandelion Taraxacum officinale and the blackberry Rubus fruticosus are aggregates with many microspecies—perhaps 400 in the case of the blackberry and over 200 in the dandelion, complicated by hybridisation , apomixis and polyploidy , making gene flow between populations difficult to determine, and their taxonomy debatable. Species complexes occur in insects such as Heliconius butterflies, vertebrates such as Hypsiboas treefrogs, and fungi such as

3420-726: Is hard or even impossible to test. Later biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, and the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: (1) agamospecies for asexual organisms (2) biospecies for reproductively isolated sexual organisms (3) ecospecies based on ecological niches (4) evolutionary species based on lineage (5) genetic species based on gene pool (6) morphospecies based on form or phenotype and (7) taxonomic species,

3510-452: Is high gene flow with the non-serpentine communities that can cause genotypic pollution , hybridization , and nonviable offspring. The unique plants that survive in serpentine soils have been used in the process of phytoremediation , a type of bioremediation . Since these plants developed specialized adaptations to high concentrations of heavy metals, they have been used to remove heavy metals from polluted soil. Serpentine barrens are

3600-458: Is more diminutive than the lower, and is entire and shallowly hooded. The flower bracts are broadly ovate in shape with puberulent hairs and shiny. The bracts have seven to nine spines each. The anthers are short and hairy. The style is glabrous . Plants bloom in April into late June, with each flower when fertilized producing four nut-like seeds. Plants are self-fertile. The range of this species

3690-503: Is named in honor of Harry Arnold Dutton , who in 1949 located a patch of another rare plant Cupressus abramsiana on nearby Butano Ridge . A. duttonii upper stamens are fertile, while the other species have sterile upper stamens. The presence of these fertile upper stamens is used to separate it as a different species from Acanthomintha obovata , in the past A. duttonii was referred to as subspecies of A. obovata ( Acanthomintha obovata ssp. duttonii ), James D. Jokerst split

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3780-550: Is needed to see if this will potentially have a negative effect on human health as it pertains to beef consumption. Soldiers Delight Natural Environment Area in Baltimore County, Maryland , covers 1,900 acres of serpentine barren. The area has over 38 rare, threatened, and endangered plant species; as well as rare insects, rocks, and minerals. Rock Springs Nature Preserve in Lancaster County, Pennsylvania

3870-403: Is no easy way to tell whether related geographic or temporal forms belong to the same or different species. Species gaps can be verified only locally and at a point of time. One is forced to admit that Darwin's insight is correct: any local reality or integrity of species is greatly reduced over large geographic ranges and time periods. The botanist Brent Mishler argued that the species concept

3960-478: Is not valid, notably because gene flux decreases gradually rather than in discrete steps, which hampers objective delimitation of species. Indeed, complex and unstable patterns of gene flux have been observed in cichlid teleosts of the East African Great Lakes . Wilkins argued that "if we were being true to evolution and the consequent phylogenetic approach to taxa, we should replace it with

4050-409: Is often reddish, brown, or gray in color due to its high iron and low organic content. Geologically, areas with serpentine bedrock are characteristically steep, rocky, and vulnerable to erosion, which causes many serpentine soils to be rather shallow. The shallow soils and sparse vegetation lead to elevated soil temperatures and dry conditions. Due to their ultramafic origin, serpentine soils also have

4140-566: Is sharply limited within a portion of central San Mateo County on the eastern lower slopes of the Santa Cruz Mountains . The single remaining large population, in Edgewood County Park , is a relict of a more extensive colony damaged by off-road motor-vehicle use. There is an introduced population at Pulgas Ridge Open Space Preserve , and native fragments along the lower slopes above Crystal Springs Reservoir in

4230-586: Is similar to Mayr's Biological Species Concept, but stresses genetic rather than reproductive isolation. In the 21st century, a genetic species could be established by comparing DNA sequences. Earlier, other methods were available, such as comparing karyotypes (sets of chromosomes ) and allozymes ( enzyme variants). An evolutionarily significant unit (ESU) or "wildlife species" is a population of organisms considered distinct for purposes of conservation. In palaeontology , with only comparative anatomy (morphology) and histology from fossils as evidence,

4320-512: Is sometimes an important source of genetic variation. Viruses can transfer genes between species. Bacteria can exchange plasmids with bacteria of other species, including some apparently distantly related ones in different phylogenetic domains , making analysis of their relationships difficult, and weakening the concept of a bacterial species. Serpentine soil Serpentine soils exhibit distinct chemical and physical properties and are generally regarded as poor soils for agriculture. The soil

4410-594: Is threatened by hybridisation, but this can be selected against once a pair of populations have incompatible alleles of the same gene, as described in the Bateson–Dobzhansky–Muller model . A different mechanism, phyletic speciation, involves one lineage gradually changing over time into a new and distinct form (a chronospecies ), without increasing the number of resultant species. Horizontal gene transfer between organisms of different species, either through hybridisation , antigenic shift , or reassortment ,

4500-611: The Streptanthus howellii ) and occasionally a carnivorous nature as seen in the Darlingtonia californica . Some examples of common serpentine tolerant plants include gray pine ( Pinus sabiniana ), Jeffrey Pine ( Pinus jeffreyi ), California lilac ( Ceanothus sp. ), manzanita ( Arctostaphylos sp. ), live oak ( Quercus sp.), California redbud ( Cercis occidentalis ), California buckeye ( Aesculus californica ), California laurel (bay tree) ( Umbellularia californica ), and

4590-530: The ICZN for animals and the ICN for plants, do not make rules for defining the boundaries of the species. Research can change the boundaries, also known as circumscription, based on new evidence. Species may then need to be distinguished by the boundary definitions used, and in such cases the names may be qualified with sensu stricto ("in the narrow sense") to denote usage in the exact meaning given by an author such as

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4680-399: The fly agaric . Natural hybridisation presents a challenge to the concept of a reproductively isolated species, as fertile hybrids permit gene flow between two populations. For example, the carrion crow Corvus corone and the hooded crow Corvus cornix appear and are classified as separate species, yet they can hybridise where their geographical ranges overlap. A ring species is

4770-507: The jaguar ( Panthera onca ) of Latin America or the leopard ( Panthera pardus ) of Africa and Asia. In contrast, the scientific names of species are chosen to be unique and universal (except for some inter-code homonyms ); they are in two parts used together : the genus as in Puma , and the specific epithet as in concolor . A species is given a taxonomic name when a type specimen

4860-453: The serpentine group , resulting in serpentine soils , with unusually high concentrations of iron , chromium , nickel , and cobalt . Serpentine barrens, as at Grass Valley, California , often consist of grassland or savannas in areas where the climate would normally lead to the growth of forests. Serpentine soils can be amended to support crops and pasture land for cattle grazing. This can be done by adding ample amounts of gypsum to

4950-406: The "cynical species concept", and arguing that far from being cynical, it usefully leads to an empirical taxonomy for any given group, based on taxonomists' experience. Other biologists have gone further and argued that we should abandon species entirely, and refer to the "Least Inclusive Taxonomic Units" (LITUs), a view that would be coherent with current evolutionary theory. The species concept

5040-572: The 1970s to 80s by off-road vehicle use and road maintenance crews. Species A species ( pl. : species) is a population of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring , typically by sexual reproduction . It is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity . Other ways of defining species include their karyotype , DNA sequence, morphology , behaviour, or ecological niche . In addition, paleontologists use

5130-562: The 1980s from 50,000 plants to as few as 5,000 plants a year. This species became federally listed as endangered in 1989. California listed San Mateo thornmint as "rare, threatened, or endangered in California" under List 1B.1 in 1979, and further classifies this plant as "seriously endangered in California". A state of California endangerment rank of S1.1 has been assigned, implying that there are fewer than six populations, fewer than 1000 individuals or fewer than 2000 acres (8 km). In

5220-548: The Nottingham Park, aka Serpentine Barrens, was recommended by UMCES as deserving of National Natural Landmark designation, on numerous grounds. They included supporting a number of rare and endemic species, an intact population of pitch pine , and also the site having historic significance. Since 1979, the Nature Conservancy has worked with the local community to protect and preserve several tracts in

5310-626: The Origin of Species explained how species could arise by natural selection . That understanding was greatly extended in the 20th century through genetics and population ecology . Genetic variability arises from mutations and recombination , while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures . Genes can sometimes be exchanged between species by horizontal gene transfer ; new species can arise rapidly through hybridisation and polyploidy ; and species may become extinct for

5400-678: The State-Line Serpentine Barrens which are home to this fragile habitat. Buck Creek Serpentine Barrens in Nantahala National Forest in Clay County, North Carolina , is another example. Dominant rock types are serpentinized dunite and olivine , with variable soil depths ranging from 0 to 60 centimetres (0 to 24 inches) and rock outcrops representing 5–10% of the local landscape. The U.S. National Vegetation Classification for this community

5490-405: The abbreviation "sp." in the singular or "spp." (standing for species pluralis , Latin for "multiple species") in the plural in place of the specific name or epithet (e.g. Canis sp.). This commonly occurs when authors are confident that some individuals belong to a particular genus but are not sure to which exact species they belong, as is common in paleontology . Authors may also use "spp." as

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5580-570: The amount of hybridisation is insufficient to completely mix their respective gene pools . A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology , genes can move freely even between distantly related bacteria, possibly extending to the whole bacterial domain. As a rule of thumb, microbiologists have assumed that members of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA–DNA hybridisation to decide if they belong to

5670-474: The biological species concept, "the several versions" of the phylogenetic species concept, and the idea that species are of the same kind as higher taxa are not suitable for biodiversity studies (with the intention of estimating the number of species accurately). They further suggested that the concept works for both asexual and sexually-reproducing species. A version of the concept is Kevin de Queiroz 's "General Lineage Concept of Species". An ecological species

5760-505: The biological species concept, a cladistic species does not rely on reproductive isolation – its criteria are independent of processes that are integral in other concepts. Therefore, it applies to asexual lineages. However, it does not always provide clear cut and intuitively satisfying boundaries between taxa, and may require multiple sources of evidence, such as more than one polymorphic locus, to give plausible results. An evolutionary species, suggested by George Gaylord Simpson in 1951,

5850-428: The boundaries between closely related species become unclear with hybridisation , in a species complex of hundreds of similar microspecies , and in a ring species . Also, among organisms that reproduce only asexually , the concept of a reproductive species breaks down, and each clone is potentially a microspecies. Although none of these are entirely satisfactory definitions, and while the concept of species may not be

5940-522: The case of A. duttonii , the criteria of occurrences and area may both be present. A global rank of G1 (critically imperilled globally) has been attached to this wildflower. Significant threats to A. duttonii identified in 1989 to 1998 were continuing urbanization of the San Francisco Peninsula, an inherently fragmented population and off-road vehicle use. Two or possibly three colonies of San Mateo thornmint may have been eradicated in

6030-538: The chemical and physical challenges presented by serpentine soils, plants have developed tolerances to drought, heavy metals, and limited nutrients. Low calcium:magnesium ratios cause limited root growth and root activity, weak cell membranes, and reduced uptake of essential nutrients. An adaptive mechanism to high magnesium soils allocates more resources to deep-growing roots. Heavy metals stunt growth, induce iron deficiency, cause chlorosis, and restrict root development. Multiple adaptive mechanisms to heavy metals include

6120-433: The concept of a chronospecies can be applied. During anagenesis (evolution, not necessarily involving branching), some palaeontologists seek to identify a sequence of species, each one derived from the phyletically extinct one before through continuous, slow and more or less uniform change. In such a time sequence, some palaeontologists assess how much change is required for a morphologically distinct form to be considered

6210-416: The concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. About 14% of these had been described by 2011. All species (except viruses ) are given a two-part name , called a "binomial". The first part of a binomial is the genus to which the species belongs. The second part

6300-830: The distribution of ophiolites . There are outcroppings of serpentine soils in the Balkan Peninsula, Turkey, Newfoundland , the island of Cyprus , the Alps, Cuba, and New Caledonia. In North America, serpentine soils also are present in small but widely distributed areas on the eastern slope of the Appalachian Mountains in the eastern United States. However, California has the majority of the continent's serpentine soils. Ecologically, serpentine soils have three main traits: poor plant productivity, high rates of endemism , and vegetation types that are distinct from neighboring areas. Serpentine plant communities range from moist bogs and fens to rocky barrens and must be able to tolerate

6390-667: The dust particles. Caution should be taken when working in serpentine soils or when working with crushed serpentine rocks. Serpentinite most often forms in oceanic crust near the surface of the earth, particularly where water circulates in cooling rock near mid-ocean ridges : masses of the resulting ultramafic rock are found in ophiolites incorporated in continental crust near present and past tectonic plate boundaries. Serpentine soils are derived from ultramafic rocks. Ultramafic rocks are igneous or metamorphic rocks that contain more than 70% iron or magnesium minerals. Serpentine soils are widely distributed on Earth, in part mirroring

6480-435: The evidence to support hypotheses about evolutionarily divergent lineages that have maintained their hereditary integrity through time and space. Molecular markers may be used to determine diagnostic genetic differences in the nuclear or mitochondrial DNA of various species. For example, in a study done on fungi , studying the nucleotide characters using cladistic species produced the most accurate results in recognising

6570-848: The exclusion of metals by restricting the uptake by the roots, compartmentalization of metals in various organs, or the development of toxicity tolerance. In nitrogen-poor sites, physiological effects on plants include impaired protein synthesis, chlorosis , reduced leaf turgor, reduced leaf and tiller number, reduced growth rate, and low seed yield. Low phosphorus levels cause similar effects of low nitrogen but also cause reduced seed size, lower root to shoot ratios, and increased water stress. Low soil moisture causes reduced nutrient uptake and transport, decreased stomatal opening, and reduced photosynthetic capacity, and also reduces plant growth and productivity. Serpentine plants have strongly developed root systems to facilitate uptake of water and nutrients. For example, Noccaea fendleri (aka Fendler's penny grass)

6660-431: The exotic Lolium multiflorum . Specific plant communities where this species is found are chaparral as well as foothill or valley grasslands. San Mateo thornmint populations occupy slopes or flatland with deep, heavy clay soil inclusions. In general, serpentine soils normally provide an inhospitable environment for most plants. Several factors contribute to serpentine soils being inhospitable to plant growth including

6750-536: The ferns Aspidotis densa and Polystichum lemmonii . Areas of serpentine soil are also home to diverse plants, many of which are rare or endangered species such as Acanthomintha duttonii , Pentachaeta bellidiflora , and Phlox hirsuta . In California, 45% of the taxa associated with serpentine are rare or endangered. In California, shrubs such as leather oak ( Quercus durata ) and coast whiteleaf manzanita ( Arctostaphylos viscida ssp. pulchella ) are typical of serpentine soils. In order to overcome

6840-427: The flower, with five or seven marginal spines, each three to seven millimeters. The virtually hairless to sparse short haired calyx is five to eight millimeters in length, while the corolla is 12 to 16 millimeters in extent. The white corolla is often tinged lavender in color; the corolla throat is cream colored and its upper lip is hooded, while the longer lower lip is reflexed and three-lobed. The upper lip

6930-571: The harsh environmental conditions of such poor soil. As a result, they are often drastically different from non-serpentine soil areas bordering the serpentine soils. Vegetative characteristics are often shared among the types of flora found on serpentine soils. They will exhibit a "stunted" growth habit, with dull waxy, gray-green leaves (seen in Eriogonum libertini ), which allow for water retention and sunlight reflection respectively. Other possible phenotypic traits include pigmented stems (as seen in

7020-415: The metamorphic reaction of olivine -rich rock, peridotite , with water. Serpentinite has a mottled, greenish-gray, or bluish-gray color and is often waxy to the touch. The rock often contains white streaks of chrysotile running through it, which are a type of naturally occurring asbestos . Asbestos is linked to an array of human health conditions such as mesothelioma from long-time exposure of breathing in

7110-483: The numerous fungi species of all the concepts studied. Versions of the phylogenetic species concept that emphasise monophyly or diagnosability may lead to splitting of existing species, for example in Bovidae , by recognising old subspecies as species, despite the fact that there are no reproductive barriers, and populations may intergrade morphologically. Others have called this approach taxonomic inflation , diluting

7200-593: The paper is accepted for publication. The type material is usually held in a permanent repository, often the research collection of a major museum or university, that allows independent verification and the means to compare specimens. Describers of new species are asked to choose names that, in the words of the International Code of Zoological Nomenclature , are "appropriate, compact, euphonious, memorable, and do not cause offence". Books and articles sometimes intentionally do not identify species fully, using

7290-674: The person who named the species, while the antonym sensu lato ("in the broad sense") denotes a wider usage, for instance including other subspecies. Other abbreviations such as "auct." ("author"), and qualifiers such as "non" ("not") may be used to further clarify the sense in which the specified authors delineated or described the species. Species are subject to change, whether by evolving into new species, exchanging genes with other species, merging with other species or by becoming extinct. The evolutionary process by which biological populations of sexually-reproducing organisms evolve to become distinct or reproductively isolated as species

7380-487: The result of misclassification leading to questions on whether there really are any ring species. The commonly used names for kinds of organisms are often ambiguous: "cat" could mean the domestic cat, Felis catus , or the cat family, Felidae . Another problem with common names is that they often vary from place to place, so that puma, cougar, catamount, panther, painter and mountain lion all mean Puma concolor in various parts of America, while "panther" may also mean

7470-586: The ring. Ring species thus present a difficulty for any species concept that relies on reproductive isolation. However, ring species are at best rare. Proposed examples include the herring gull – lesser black-backed gull complex around the North pole, the Ensatina eschscholtzii group of 19 populations of salamanders in America, and the greenish warbler in Asia, but many so-called ring species have turned out to be

7560-508: The same species. This concept was narrowed in 2006 to a similarity of 98.7%. The average nucleotide identity (ANI) method quantifies genetic distance between entire genomes , using regions of about 10,000 base pairs . With enough data from genomes of one genus, algorithms can be used to categorize species, as for Pseudomonas avellanae in 2013, and for all sequenced bacteria and archaea since 2020. Observed ANI values among sequences appear to have an "ANI gap" at 85–95%, suggesting that

7650-529: The same species. When two species names are discovered to apply to the same species, the older species name is given priority and usually retained, and the newer name considered as a junior synonym, a process called synonymy . Dividing a taxon into multiple, often new, taxa is called splitting . Taxonomists are often referred to as "lumpers" or "splitters" by their colleagues, depending on their personal approach to recognising differences or commonalities between organisms. The circumscription of taxa, considered

7740-534: The soil. By adding gypsum a more favourable calcium-to-magnesium ratio can be developed, creating a better balance of plant nutrients. This, however, poses a possible implication to grazing cattle. An article from the Journal of Trace Elements in Medicine and Biology discerned that 20% of the grazing animals had toxic levels of nickel in their kidneys, and 32% had toxic levels of copper in their liver. Further study

7830-506: The species concept and making taxonomy unstable. Yet others defend this approach, considering "taxonomic inflation" pejorative and labelling the opposing view as "taxonomic conservatism"; claiming it is politically expedient to split species and recognise smaller populations at the species level, because this means they can more easily be included as endangered in the IUCN red list and can attract conservation legislation and funding. Unlike

7920-592: The taxon in 1991. All four thornmint species are aromatic annual wildflowers native to the state of California in the US. The species have square stems that are erect growing. The leaves are petioled with leaf veins conspicuous and the leaf margins are often spiny. The inflorescences of the Acanthomintha genus are described as "head-like, in terminal clusters" by the genus authority James D. Jokerst. The flowers of this entire genus are like, most mints, two-lipped forming

8010-554: The upper two reduced. Thornmint styles are slender and their fruit is ovoid in shape with a smooth exterior texture. A. duttonii has a stem which is generally unbranched and less than twenty centimeters in length; the stem may present short hairs or none at all. Leaves of this species are eight to twelve millimeters in length, lanceolate to obovate in shape. The margins of this spiny leaf are occasionally serrate . The terminal inflorescences have bracts of about five to eleven millimeters; moreover, these bracts are ovate and green at

8100-540: The wild. It is difficult to define a species in a way that applies to all organisms. The debate about species concepts is called the species problem. The problem was recognised even in 1859, when Darwin wrote in On the Origin of Species : I was much struck how entirely vague and arbitrary is the distinction between species and varieties. He went on to write: No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of

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