85-403: Mangaon, Maharashtra, India E. g. garzetta E. g. immaculata E. g. nigripes Ardea garzetta Linnaeus, 1766 The little egret ( Egretta garzetta ) is a species of small heron in the family Ardeidae . It is a white bird with a slender black beak, long black legs and, in the western race, yellow feet. As an aquatic bird , it feeds in shallow water and on land, consuming
170-423: 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
255-400: 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
340-424: 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
425-459: A combination of over-hunting in the late medieval period and climate change at the start of the Little Ice Age . The inclusion of 1,000 egrets (among numerous other birds) in the banquet to celebrate the enthronement of George Neville as Archbishop of York at Cawood Castle in 1465 indicates the presence of a sizable population in northern England at the time, and they are also listed in
510-428: 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
595-432: 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
680-508: 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
765-465: 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
850-492: 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
935-449: 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
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#17328546298031020-400: 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
1105-449: 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
1190-605: A post-breeding total of 4,540 birds in September 2008. The first record of breeding in Scotland happened in 2020 in Dumfries & Galloway . In Ireland , the species bred for the first time in 1997 at a site in County Cork and the population has also expanded rapidly since, breeding in most Irish counties by 2010. Severe winter weather in 2010–2012 proved to be only a temporary setback, and
1275-400: 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,
1360-404: 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
1445-523: 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
1530-400: 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
1615-488: 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
1700-685: 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
1785-519: 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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#17328546298031870-506: 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
1955-447: 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
2040-515: 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,
2125-557: A variety of small creatures. It breeds colonially , often with other species of water birds, making a platform nest of sticks in a tree, bush or reed bed. A clutch of three to five bluish-green eggs is laid and incubated by both parents for about three weeks. The young fledge at about six weeks of age. Its breeding distribution is in wetlands in warm temperate to tropical parts of Asia , Africa , Australia , and Europe . A successful colonist, its range has gradually expanded north, with stable and self-sustaining populations now present in
2210-617: A wider area and have been observed from Suriname and Brazil in the south to Newfoundland , Quebec and Ontario in the north. Birds on the east coast of North America are thought to have moved north with snowy egrets from the Caribbean. In June 2011, a little egret was spotted in Maine, in the Scarborough Marsh, near the Audubon Center. Species A species ( pl. : species) is
2295-438: 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
2380-428: Is 55–65 cm (22–26 in) long with an 88–106 cm (35–42 in) wingspan, and weighs 350–550 g (12–19 oz). Its plumage is normally entirely white, although there are dark forms with largely bluish-grey plumage. In the breeding season, the adult has two long plumes on the nape that form a crest. These plumes are about 150 mm (6 in) and are pointed and very narrow. There are similar feathers on
2465-400: 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
2550-458: 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
2635-414: 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
Little egret - Misplaced Pages Continue
2720-412: 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,
2805-594: Is continuing to expand westward, and the species has begun to colonise the New World; it was first seen in Barbados in 1954 and first bred there in 1994. The International Union for Conservation of Nature has assessed the bird's global conservation status as being of " least concern ". The little egret was formally described by the Swedish naturalist Carl Linnaeus in 1766 in the twelfth edition of his Systema Naturae under
2890-403: 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
2975-671: 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
3060-726: 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,
3145-403: 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
3230-468: 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
3315-586: 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,
3400-404: 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. Lore (anatomy) The lore (adj. loreal )
3485-474: Is the region between the eyes and nostrils of birds, reptiles, and amphibians. In ornithology, the lore is the region between the eye and bill on the side of a bird's head . This region is sometimes featherless, and the skin may be tinted, as in many species of the cormorant family. This area, which is directly in front of the eye, features a "loral stripe" in many bird species including the red-capped plover . In amphibians and reptiles , lore pertains to
Little egret - Misplaced Pages Continue
3570-594: 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 ,
3655-521: The Cape Verde Islands, the birds nest on cliffs. Pairs defend a small breeding territory, usually extending around 3 to 4 m (10 to 13 ft) from the nest. The three to five eggs are incubated by both adults for 21 to 25 days before hatching. They are oval in shape and have a pale, non-glossy, blue-green shell colour. The young birds are covered in white down feathers , are cared for by both parents and fledge after 40 to 45 days. Globally,
3740-523: 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
3825-515: The United Kingdom . In warmer locations, most birds are permanent residents; northern populations, including many European birds, migrate to Africa and southern Asia to over-winter there. The birds may also wander north in late summer after the breeding season, and their tendency to disperse may have assisted in the recent expansion of the bird's range. At one time common in Western Europe, it
3910-705: The binomial name Ardea garzetta . It is now placed with 12 other species in the genus Egretta that was introduced in 1817 by the German naturalist Johann Reinhold Forster with the little egret as the type species . The genus name comes from the Provençal French Aigrette , "egret", a diminutive of Aigron , "heron". The species epithet garzetta is from the Italian name for this bird, garzetta or sgarzetta . Two subspecies are recognised: Three other egret taxa have at times been classified as subspecies of
3995-399: 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
4080-498: 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
4165-406: 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
4250-622: 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
4335-405: 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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#17328546298034420-485: The abundance of prey . They use a variety of methods to procure their food; they stalk their prey in shallow water, often running with raised wings or shuffling their feet to disturb small fish, or may stand still and wait to ambush prey. They make use of opportunities provided by cormorants disturbing fish or humans attracting fish by throwing bread into water. On land they walk or run while chasing their prey, feed on creatures disturbed by grazing livestock and ticks on
4505-570: 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
4590-474: 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
4675-505: 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,
4760-594: The bird preferring open locations to dense cover. On the coast it inhabits mangrove areas, swamps, mudflats, sandy beaches and reefs. Rice fields are an important habitat in Italy, and coastal and mangrove areas are important in Africa. The bird often moves about among cattle or other hoofed mammals. Little egrets are sociable birds and are often seen in small flocks. Nevertheless, individual birds do not tolerate others coming too close to their chosen feeding site, though this depends on
4845-456: The birds could be plucked without being killed but most of the supply of so-called " Osprey plumes" was obtained by hunting, which reduced the population of the species to dangerously low levels and stimulated the establishment of Britain's Royal Society for the Protection of Birds in 1889. By the 1950s, the little egret had become restricted to southern Europe, and conservation laws protecting
4930-428: 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
5015-424: The breast, but the barbs are more widely spread. There are also several elongated scapular feathers that have long loose barbs and may be 200 mm (8 in) long. During the winter the plumage is similar but the scapulars are shorter and more normal in appearance. The bill is long and slender and it and the lores are black. There is an area of greenish-grey bare skin at the base of the lower mandible and around
5100-433: 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
5185-416: 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
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#17328546298035270-515: The coronation feast of King Henry VI in 1429. They had become scarce by the mid-16th century, when William Gowreley, "yeoman purveyor to the Kinges mowthe", "had to send further south" for egrets. In 1804 Thomas Bewick commented that if it were the same bird as listed in Neville's bill of fare "No wonder this species has become nearly extinct in this country!" Further declines occurred throughout Europe as
5355-435: 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
5440-408: The eye which has a yellow iris . The legs are black and the feet yellow. Juveniles are similar to non-breeding adults but have greenish-black legs and duller yellow feet, and may have a certain proportion of greyish or brownish feathers. The subspecies nigripes differs in having yellow skin between the bill and eye, and blackish feet. During the height of courtship, the lores turn red and the feet of
5525-650: The latter. During the late twentieth century, the range of the little egret expanded northwards in Europe and into the New World, where a breeding population was established on Barbados in 1994. The birds have since spread elsewhere in the Caribbean region and on the Atlantic coast of the United States. The little egret's habitat varies widely, and includes the shores of lakes, rivers, canals, ponds, lagoons, marshes and flooded land,
5610-791: The little egret has now started to colonise the New World . The first record there was on Barbados in April 1954. The bird began breeding on the island in 1994 and now also breeds in the Bahamas . They may have made the crossing from Western Africa. Ringed birds from Spain provide a clue to the birds' origin. The birds are very similar in appearance to the snowy egret and share colonial nesting sites with these birds in Barbados, where they are both recent arrivals. The little egrets are larger, have more varied foraging strategies and exert dominance over feeding sites. Little egrets are seen with increasing regularity over
5695-624: The little egret in the past but are now regarded as two separate species. These are the western reef heron Egretta gularis which occurs on the coastline of West Africa ( Egretta gularis gularis ) and from the Red Sea to India ( Egretta gularis schistacea ), and the dimorphic egret ( Egretta dimorpha ), found in East Africa , Madagascar , the Comoros and the Aldabra Islands . The adult little egret
5780-506: The little egret is not listed as a threatened species and has in fact expanded its range over the last few decades. The International Union for Conservation of Nature states that their wide distribution and large total population means that they are a species that cause them " least concern ". Historical research has shown that the little egret was once present, and probably common, in Ireland and Great Britain , but became extinct there through
5865-819: The livestock, and even scavenge . Their diet is mainly fish , but amphibians , small reptiles , mammals and birds are also eaten, as well as crustaceans , molluscs , insects , spiders and worms . Little egrets nest in colonies, often with other wading birds. On the coasts of western India these colonies may be in urban areas, and associated birds include cattle egrets ( Bubulcus ibis ), black-crowned night herons ( Nycticorax nycticorax ) and black-headed ibises ( Threskiornis melanocephalus ). In Europe, associated species may be squacco herons ( Ardeola ralloides ), cattle egrets, black-crowned night herons and glossy ibises ( Plegadis falcinellus ). The nests are usually platforms of sticks built in trees or shrubs, or in reed beds or bamboo groves. In some locations such as
5950-478: 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
6035-585: 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
6120-674: 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
6205-537: The plumes of the little egret and other egrets were in demand for decorating hats. They had been used in the plume trade since at least the 17th century but in the 19th century it became a major craze and the number of egret skins passing through dealers reached into the millions. Complete statistics do not exist, but in the first three months of 1885, 750,000 egret skins were sold in London, while in 1887 one London dealer sold 2 million egret skins. Egret farms were set up where
6290-487: 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
6375-573: 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
6460-508: 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
6545-529: 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
6630-502: 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
6715-543: The species continues to spread. In Australia, its status varies from state to state. It is listed as "Threatened" on the Victorian Flora and Fauna Guarantee Act 1988 . Under this act, an Action Statement for the recovery and future management of this species has been prepared. On the 2007 advisory list of threatened vertebrate fauna in Victoria, the little egret is listed as endangered . With its range continuing to expand,
6800-573: The species were introduced. This allowed the population to rebound strongly; over the next few decades it became increasingly common in western France and later on the north coast. It bred in the Netherlands in 1979 with further breeding from the 1990s onward. About 22,700 pairs are thought to breed in Europe, with populations stable or increasing in Spain, France and Italy but decreasing in Greece. In Britain it
6885-609: The western race ( E. g. garzetta ) includes southern Europe, the Middle East, much of Africa and southern Asia . Northern European populations are migratory , mostly travelling to Africa although some remain in southern Europe, while some Asian populations migrate to the Philippines. The eastern race, ( E. g. nigripes ), is resident in Indonesia and New Guinea, while E. g. immaculata inhabits Australia and New Zealand, but does not breed in
6970-537: 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
7055-401: The yellow-footed races turn red. Little egrets are mostly silent but make various croaking and bubbling calls at their breeding colonies and produce a harsh alarm call when disturbed. To the human ear, the sounds are indistinguishable from the black-crowned night heron ( Nycticorax nycticorax ) and the cattle egret ( Bubulcus ibis ) with which it sometimes associates. The breeding range of
7140-649: Was a rare vagrant from its 16th-century disappearance until the late 20th century, and did not breed. It has however recently become a regular breeding species and is commonly present, often in large numbers, at favoured coastal sites. The first recent breeding record in England was on Brownsea Island in Dorset in 1996, and the species bred in Wales for the first time in 2002. The population increase has been rapid subsequently, with over 750 pairs breeding in nearly 70 colonies in 2008, and
7225-516: Was hunted extensively in the 19th century to provide plumes for the decoration of hats and became locally extinct in northwestern Europe and scarce in the south. Around 1950, conservation laws were introduced in southern Europe to protect the species and their numbers began to increase. By the beginning of the 21st century the bird was breeding again in France, the Netherlands, Ireland and Britain. Its range
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