90-411: The zander ( Sander lucioperca ), sander or pikeperch , is a species of ray-finned fish from the family Percidae , which also includes perch , ruffe and darter . It is found in freshwater and brackish habitats in western Eurasia . It is a popular game fish and has been introduced to a variety of localities outside its native range. It is the type species of the genus Sander . The zander
180-558: A Northern pike ( Esox lucius ), hence the alternative English common name of pikeperch. The upper part of its body is green-brown in colour and this extends onto the sides as dark vertical bars, in a pattern not dissimilar to that of the European perch ( Perca fluviatilis ) while the lower part of the body is creamy-white. Their caudal fin is dark and the pectoral , pelvic and anal fins are paler off-white in colour. The dorsal and caudal fins are marked with rows of black spots on
270-423: 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
360-515: 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 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
450-542: A two-part name , called a "binomial". The first part of a binomial is the genus to which the species belongs. The second part 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,
540-400: 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
630-559: A "dirty dozen" non-native species most likely to harm native wildlife along rivers in Great Britain. Their success in establishing themselves was owed to a number of factors, one of which is that they are particularly well adapted to life in the slow-flowing, sparsely vegetated, rather murky waters that comprise so many of the British lowland rivers. Zander thrive in water with rather low visibility, unlike pike, which often dominate
720-424: 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
810-428: 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
900-455: A conservation measure, the law regulates the minimum size of zander considered mature enough to be eaten. In July 2009, in a rare occurrence, a zander bit bathers swimming in the Swiss part of Lake Maggiore , sending two people to the emergency room; the worst bite inflicted a wound about 10 centimeters long. The 70-cm 8-kg fish was later caught by the local police who cooked it and offered it to
990-504: A delicate flavour. Although it is not generally bred for food, its adaptability makes zander fishery quite sustainable. Indeed, in some regions release of young zanders is restricted, as natural stocks already provide a sufficient supply for the market, while boosting the population of this large predator would have an adverse effect on populations of its prey. Zander is especially well suited for fish fillets . It can also be served whole, baked, smoked or cooked. In some culinary circles, zander
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#17327721227511080-432: 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
1170-508: 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
1260-465: 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
1350-555: A miniature railway and a garden/visitor centre. It was built by William Russell, 1st Baron Russell of Thornhaugh . Woburn Abbey, comprising Woburn Park and its buildings, was set out and founded as a Cistercian abbey in 1145. The Cistercian community was dissolved by Henry VIII in 1538. In 1547 the estate became the seat of the Russell family and the Dukes of Bedford , Around 1630, Francis Russell, 4th Earl of Bedford undertook
1440-492: 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
1530-449: 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
1620-400: 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
1710-400: 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,
1800-404: 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
1890-523: 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
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#17327721227511980-400: 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
2070-491: 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
2160-685: 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
2250-528: 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
2340-517: 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
2430-447: 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
2520-515: 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,
2610-438: 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
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
2790-458: 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
Zander - Misplaced Pages Continue
2880-583: Is a single flat spine on the operculum . Like other members of the perch family the zander has a split dorsal fin with the first dorsal fin having 13–20 spines and 18–24 soft rays, while the anal fin has 2–3 rays and 10–14 soft rays. The caudal fin is long and forked. The zander has a maximum published standard length 100 centimetres (39 in), although they are more commonly found at around 50 centimetres (20 in). This species can reach 20 kg (44 lb) of weight, although typical catches are considerably smaller. The IGFA All-Tackle world record zander
2970-483: Is appreciated even more highly than salmon. Even the offals can be cooked into consommé . In 2004, it was revealed that some restaurants in the Minneapolis-St. Paul area of Minnesota were serving imported zander instead of the closely related North American walleye (the state fish, and a popular food in the region). While zander and walleye are almost indistinguishable by taste, the restaurants were selling
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
3150-403: 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
3240-426: Is expected to increase. High investment and maintenance costs of RAS require farming of high value species with good market acceptance such as zander. 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
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,
3510-492: Is in April and May, although exceptionally they may spawn from late February through to July, and the actual period depends on latitude and altitude. The determining factor is that it needs temperatures to reach 10–14 °C (50–57 °F) before spawning starts. Zander have a maximum lifespan of 17 year and they are sexually mature at 3–10 years old, with 4 years old being typical. A large number of parasites are known to infect
3600-759: Is in Finland. It has been introduced to Great Britain, southern Europe, and continental Europe west of the Elbe, Ebro, Tagus and Jucar drainages, as well as to Anatolia, North Africa, Siberia, Kyrgyzstan, and Kazakhstan. In the UK, zander was originally introduced in 1878 by Francis Russell, 9th Duke of Bedford , into lakes on his Woburn Abbey estate and soon after that into the Great Ouse Relief Channel in The Fens . British Waterways included zander among
3690-403: 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
Zander - Misplaced Pages Continue
3780-478: 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
3870-586: 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,
3960-434: 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. Woburn Abbey Woburn Abbey ( / ˈ w oʊ b ər n / ), occupying
4050-594: 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 ,
4140-848: The Government of Ontario is preemptively treating zander as a future invasive species. In the Netherlands, zander may be found (natively) in many major waterways, including the Waal , Hollands Diep , and other distributaries or estuaries of the Rhine, and are also particularly common in the canals of Amsterdam. Zander inhabit freshwater bodies, especially large rivers and eutrophic lakes. They can tolerate brackish water and will make use of coastal lakes and estuaries. Individuals living in brackish water habitats migrate upriver, as far as 250 kilometres (160 miles) for spawning. Zander are carnivorous and
4230-530: 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
4320-399: 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
4410-507: 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
4500-406: 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
4590-501: The 1960s and 1970s, leading to decreases in populations of native cyprinids . Recorded predators of the zander include other zanders, as well as European eels ( Anguilla anguilla ), Northern pike, European perch, the wels catfish ( Silurus glanis ) and the Caspian seal ( Phoca caspia ). The zander is considered one of the most valuable food fish native to Europe. It is esteemed for its light, firm but tender meat with few bones and
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#17327721227514680-695: The Abbey into a large theme park with the help of John Wardley , creator of the roller coasters " Nemesis " and " Oblivion ". However, Tussauds bought Alton Towers and built one there instead. From 1999 to 2002, the Marquess and the Marchioness, the former Henrietta Joan Tiarks, were the subjects of the Tiger Aspect Productions reality series Country House in three series, totalling 29 episodes, which aired on BBC Two . It detailed
4770-564: The European fish under the name "walleye", which is an illegal practice. An investigation by the U.S. Food and Drug Administration followed. In Ohio, many restaurants were caught using juvenile zander fillets in the 40 to 80 gram range in place of the Lake Erie yellow perch . Shortages of the perch along with skyrocketing prices caused wholesalers and restaurants to use the juvenile zander for popular "pike perch fillets". In Finland , as
4860-522: The North American clade, which the walleye ( S. vitreus ) and the sauger ( S. canadensis ) belong to, around 20.8 million years ago. Within the European clade the Volga pikeperch ( S. volgaensis ) is the most basal taxon and shares features with the North American clade, such as being a broadcast spawner. In contrast in the zander and the estuarine perch ( S. marinus ) the males build nests and
4950-626: 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
5040-603: The United Kingdom zander thrive in canals where the water is turbid due to the boat traffic and although their favoured prey in these waters is common roach they have a high impact on the populations of gudgeon ( Gobio gobio ). The zander spawns over gravel in flowing water, the males defend a territory in which they dig shallow depressions in sand or gravel which are roughly 50 centimetres (20 in) across and 5–10 centimetres (2.0–3.9 in) in depth in sand or gravel. They will also nest among exposed plant roots and
5130-405: 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
5220-527: The adults feed on smaller schooling fish. Studies around the Baltic Sea have found them to prey on the European smelt ( Osmerus eperlanus ), ruffe ( Gymnocephalus cernua ), European perch, vendace ( Coregonus albula ) and the common roach ( Rutilus rutilus ), They were also found to be cannibalistic on smaller zanders. They have also been recorded feeding on smolts of sea trout ( Salmo trutta morph. trutta ) and Atlantic salmon ( Salmo salar ). In
5310-570: 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
5400-469: The area. After visiting them Adams wrote in his diary " Stowe , Hagley , and Blenheim , are superb; Woburn, Caversham , and the Leasowes are beautiful. Wotton is both great and elegant, though neglected". However he was also damning about the means used to finance the large estates, and he did not think that the embellishments to the landscape made by the owners of the great country houses would suit
5490-474: 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
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#17327721227515580-505: 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,
5670-428: 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
5760-433: 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
5850-707: The daily life and the business of running the Abbey. The Marquess of Tavistock became the 14th Duke on the death of his father in November 2002 in Santa Fe, New Mexico , United States. The 14th Duke was the briefest holder of the Dukedom and died in June 2003. On the death of the 14th Duke, his son Andrew became the 15th Duke, and he continues his father's work in running the Woburn Abbey Estate. The building
5940-479: The east of the village of Woburn , Bedfordshire , England, is a country house , the family seat of the Duke of Bedford . Although it is still a family home to the current duke, it is open on specified days to visitors, along with the diverse estate surrounding it, including the historic landscape gardens and deer park (by Humphry Repton ), as well as more recently added attractions including Woburn Safari Park ,
6030-415: The eggs are laid onto these roots. The nests are normally at depths of 1 to 3 metres (39 to 118 in) in turbid water. Spawning takes place in pairs, at night and at daybreak. When they are spawning the female is stationary above the male's nest and the male rapidly swims around her, keeping a distance of around 1 metre (3.3 ft) from the nesting depression. The male then orients himself perpendicular to
6120-435: 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
6210-502: The family estates over to the National Trust , he kept ownership and opened the Abbey to the public for the first time in 1955. It soon gained in popularity and in its first ten years, it had ticket sales of $ 11 million, helping to pay off much of the death duties. Other amusements were added, including Woburn Safari Park on the grounds of the Abbey in 1970. Asked about the unfavourable comments by other aristocrats when he turned
6300-403: The family home into a safari park, the 13th Duke said, "I do not relish the scorn of the peerage, but it is better to be looked down on than overlooked." The 13th Duke moved to Monte Carlo in 1975. His son Robin , who enjoyed the courtesy title Marquess of Tavistock, ran the Abbey with his wife in his father's absence. In the early 1990s, the Marquess and The Tussauds Group planned to turn
6390-534: The female spawn into these nests and the males then guard the eggs and fry. The lineage leading to the zander is thought to have diverged from the common ancestor with the Volga pikeperch circa 13.8 million years ago while the split from the estuarine perch took place around 9.1 million years ago. The zander is the largest member of the Percidae and it usually has a long and muscular body which bears some resemblance to
6480-484: The first rebuilding, demolishing or incorporating original abbey building and built the manor house on the monastic site, although the name Abbey was retained. The second rebuilding occurred under architects Henry Flitcroft and John Sanderson between 1747 and 1761. In April 1786 John Adams and Thomas Jefferson , both future Presidents of the United States, visited Woburn Abbey and other notable houses in
6570-417: The membranes between the spines and rays, these are largest and most obvious on the first dorsal fin. The juveniles are silvery in colour, becoming darker as they age. They have powerful jaws which are armed with many sharp teeth with two long canines in the front of each jaw. They have large bulbous eyes which are opaque when the fish is living in particularly turbid conditions, an adaptation to low light. There
6660-584: The more rugged American countryside. Further rework undertaken between 1787 and 1790 was directed by Henry Holland . Visiting Woburn Abbey in March 1939, the MP and diarist Henry Channon described the well-kept-up "feudal magnificance" of the estate shortly before the outbreak of war. This included more than twenty drawing rooms, thirty cars and whole rooms devoted each to collections of Joshua Reynolds , Canalettos and Van Dyck paintings. From 1941 Woburn Abbey
6750-483: 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
6840-593: 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
6930-674: 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
7020-594: The predator fish niche in clear water. However, zander need plenty of oxygen and soon disappear from eutrophic areas. Zander were stocked in Spiritwood Lake, North Dakota in 1989 and have remained ever since. Ecologists believe that if establishment occurs in the Great Lakes they will compete with game fish such as the closely related Walleye or the Yellow perch for food and habitat . Therefore
7110-487: 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
7200-586: 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
7290-508: 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
7380-529: 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
7470-506: 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
7560-423: The substrate and the pair swim around swiftly, releasing the eggs and sperm. The female departs after releasing her eggs. The male remains at the nest and defends it, fanning the eggs using the pectoral fins. Each female lays all of her eggs at once and only spawns once a year. The larvae are attracted to light and after they leave the nest they feed on zooplankton and small pelagic animals. They normal spawning season
7650-636: The tourists for the trouble it caused. As the largest member of the perch family, zander is a popular game fish in the United Kingdom. However, it is legally a non-native invasive species ; any zander caught by anglers must be destroyed. Increasing demand for zander for human consumption has attracted great attention of fish farmers. Today, elaborated protocols for the reproduction and on-growing of zander are available. Throughout Europe, an increasing number of aquaculture facilities produce zander for stocking or human consumption, mainly in recirculating aquaculture systems (RAS). Production volume remains low, but
7740-540: 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
7830-413: The zander's skin, eyes and internal organs. Its gastrointestinal tract can host the nematode Anisakis , which can be transmitted to humans if the fish is smoked, fried or otherwise cooked at temperatures lower than 50 °C (122 °F). The zander is also a vector of the trematode Bucephalus polymorphus and may have been responsible for spreading the parasite to some French river systems during
7920-520: Was caught in Lago Maggiore, Switzerland in June 2016 weighing 11.48 kg (25.3 lb). Zander reach an average length of 40–80 cm (15.5–31.5 in) with a maximum length of 120 cm (47 in). The zander is very widely distributed across Eurasia, occurring in the drainages of the Caspian, Baltic, Black, Aral, North and Aegean Sea basins. The northern boundary of its distribution
8010-407: Was first formally described in 1758 as Perca lucioperca by Carolus Linnaeus in volume 1 of the tenth edition of Systema Naturae and he gave the type locality as "European lakes". When Lorenz Oken (1779–1851) created the genus Sander he made Perca lucioperca its type species . The zander is part of the European clade within the genus Sander which split from a common ancestor with
8100-460: Was the headquarters of the secretive Political Warfare Executive (PWE) which had its London offices at the BBC's Bush House . Following World War II , dry rot was discovered and half the Abbey was subsequently demolished. When the 12th Duke died in 1953, his son the 13th Duke was exposed to death duties of $ 14 million and the Abbey was a half-demolished, half-derelict house. Instead of handing
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