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Tilapiine Cichlid
The Tilapiini (occasionally Tilapini) are a tribe within the family Cichlidae commonly known as tilapiine cichlids. Formerly this tribe contained many other genera and species, including the economically important ''Oreochromis'' and ''Sarotherodon'', but a taxonomic review found that this grouping was paraphyletic and most were moved to Coelotilapini, Coptodonini, Heterotilapini, Oreochromini and Pelmatolapiini. Together, most species in these tribes are called "tilapias". In a more distant past, a number of other, more different genera like ''Steatocranus'' also were included in Tilapiini. With these as separate, Tilapiini now is a much more restricted tribe with only three genera and about half a dozen species from Central and Southern Africa. Systematics The tilapiines were recognised by the ichthyologist Ethylwynn Trewavas mtDNA-based phylogenies of tilapiines must be evaluated with caution, however, as they are usually close to, but do not represent the true evolutionar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tilapia Sparrmanii
''Tilapia sparrmanii'', the banded tilapia, or vlei kurper, is a widespread and adaptable cichlid fish that is found in warmer freshwater habitats of southern Africa. They prefer water with ample plant cover, and occur naturally as far north as DR Congo and Tanzania. They have been introduced locally in the northern hemisphere. Younger banded tilapia feed on crustaceans and insect larvae, while the adults feed on terrestrial and aquatic plants and other debris. They undertake local migrations and may shoal before and during spawning time. They guard their own eggs, and although they may move eggs or fry in the mouth, they are not known to be actual mouthbrooders like several other tilapia species. This species can reach a length of TL and is an important foodfish. The identity of the person honoured in the specific name is uncertain but it is probably the Swedish naturalist Anders Sparrman (1748-1820) who was in the Cape A cape is a clothing accessory or a sleeveless ou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterotilapia
''Heterotilapia'' is a genus of cichlid fish that are native to rivers from Guinea-Bissau to Liberia in tropical West Africa. Formerly considered a subgenus of ''Tilapia'', in 2013, it was elevated to genus rank. They are medium-large cichlids, up to about in standard length depending on the species, and with a distinctive dark-and-light banded pattern. They are substrate spawners and brooders (not mouthbrooders as some other tilapia Tilapia ( ) is the common name for nearly a hundred species of cichlid fish from the coelotilapine, coptodonine, heterotilapine, oreochromine, pelmatolapiine, and tilapiine tribes (formerly all were "Tilapiini"), with the economically most ...s). ''H. buttikoferi'' is a common species that also has been introduced outside its native range, but ''H. cessiana'' is highly localized and critically endangered. Species Two recognized species are in this genus: * '' Heterotilapia buttikoferi'' ( Hubrecht, 1881) (zebra tilapia) * '' Heterotilapi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sample Size
Sample size determination is the act of choosing the number of observations or Replication (statistics), replicates to include in a statistical sample. The sample size is an important feature of any empirical study in which the goal is to make statistical inference, inferences about a statistical population, population from a sample. In practice, the sample size used in a study is usually determined based on the cost, time, or convenience of collecting the data, and the need for it to offer sufficient statistical power. In complicated studies there may be several different sample sizes: for example, in a stratified sampling, stratified survey sampling, survey there would be different sizes for each stratum. In a census, data is sought for an entire population, hence the intended sample size is equal to the population. In experimental design, where a study may be divided into different treatment groups, there may be different sample sizes for each group. Sample sizes may be chosen in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudocrenilabrinae
The Pseudocrenilabrinae are a subfamily in the cichlid family of fishes to which, according to a study from 2004, includes all the Middle Eastern and African cichlids with the exception of the unusual '' Heterochromis multidens'' and the Malagasy species. This subfamily includes more than 1,100 species. Previous authors recognized additional African subfamilies, e.g. the Tilapiinae of Hoedeman (1947), Tylochrominae of Poll (1986), or Boulengerochrominae of Tawil (2001). To this subfamily belong the cichlids from the African Great Lakes, such as the utaka and mbuna in Lake Malawi, and various species from Lake Victoria and Lake Tanganyika. The Pseudocrenilabrinae tribes Haplochromini and Oreochromini are widespread in Africa and also found in the Middle East, while Chromidotilapiini, Hemichromini and Tylochromini are primarily West and Central African. The remaining tribes are largely or entirely restricted to Lake Tanganyika. Systematics Apart from the tribes mentioned in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Pool
The gene pool is the set of all genes, or genetic information, in any population, usually of a particular species. Description A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection. Meanwhile, low genetic diversity (see inbreeding and population bottlenecks) can cause reduced biological fitness and an increased chance of extinction, although as explained by genetic drift new genetic variants, that may cause an increase in the fitness of organisms, are more likely to fix in the population if it is rather small. When all individuals in a population are identical with regard to a particular phenotypic trait, the population is said to be 'monomorphic'. When the individuals show several variants of a particular trait they are said to be polymorphic. History The Russian geneticist Alexander Sergeevich Serebrovsky first formulated the concept in the 1920s as ''genofond'' (gene fund), a w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybrid (biology)
In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in blending inheritance), but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are. Species are reproductively isolated by strong barriers to hybridisation, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or the developing embryo. Some act before fertilization and others after it. Similar barriers exist in plants, with differences in flowering tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenies
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical or genetic characteristics. All life on Earth is part of a single phylogenetic tree, indicating common ancestry. In a ''rooted'' phylogenetic tree, each node with descendants represents the inferred most recent common ancestor of those descendants, and the edge lengths in some trees may be interpreted as time estimates. Each node is called a taxonomic unit. Internal nodes are generally called hypothetical taxonomic units, as they cannot be directly observed. Trees are useful in fields of biology such as bioinformatics, systematics, and phylogenetics. ''Unrooted'' trees illustrate only the relatedness of the leaf nodes and do not require the ancestral root to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylwynn Trewavas
Ethelwynn Trewavas (5 November 1900 – 16 August 1993) was an ichthyologist at the British Museum of Natural History. She was known for her work on the families Cichlidae and Sciaenidae. She worked with Charles Tate Regan, another ichthyologist and taxonomist. Academic studies and career She received her bachelor's degree and Board of Education Certificate in Teaching in 1921 from Reading University, and then worked as a teacher before being employed by the King's College of Household and Social Science as a part-time demonstrator, spending most of her time on research. She was taught by Dr. Nellie B. Eales when associated with the Freshwater Biological Association. She met Charles Regan and was employed by him as his assistant until hired by the British Museum (Natural History) as Assistant Keeper in 1935. She was appointed Deputy Keeper of Zoology in 1958, and retired in 1961. She served as the senior scientist in the Fish Section of the British Museum (Natural History ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyology
Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of October 2016, with approximately 250 new species described each year. Etymology The word is derived from the Greek words ἰχθύς, ''ikhthus'', meaning "fish"; and λογία, ''logia'', meaning "to study". History The study of fish dates from the Upper Paleolithic Revolution (with the advent of "high culture"). The science of ichthyology was developed in several interconnecting epochs, each with various significant advancements. The study of fish receives its origins from humans' desire to feed, clothe, and equip themselves with useful implements. According to Michael Barton, a prominent ichthyologist and professor at Centre College, "the earliest ichthyologists were ''hunters and gatherers'' who had learned how to obtain the most use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Africa
Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number of river systems; the Zambezi River being the most prominent. The Zambezi flows from the northwest corner of Zambia and western Angola to the Indian Ocean on the coast of Mozambique. Along the way, the Zambezi River flows over the mighty Victoria Falls on the border between Zambia and Zimbabwe. Victoria Falls is one of the largest waterfalls in the world and a major tourist attraction for the region. Southern Africa includes both subtropical and temperate climates, with the Tropic of Capricorn running through the middle of the region, dividing it into its subtropical and temperate halves. Countries commonly included in Southern Africa include Angola, Botswana, the Comoros, Eswatini, Lesotho, Madagascar, Malawi, Mauritius, Mozambique, Namib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Africa
Central Africa is a subregion of the African continent comprising various countries according to different definitions. Angola, Burundi, the Central African Republic, Chad, the Democratic Republic of the Congo, the Republic of the Congo, Equatorial Guinea, Gabon, Rwanda, and São Tomé and Príncipe are members of the Economic Community of Central African States (ECCAS). Six of those states (the Central African Republic, Chad, the Republic of the Congo, Equatorial Guinea, and Gabon) are also members of the Economic and Monetary Community of Central Africa (CEMAC) and share a common currency, the Central African CFA franc. The African Development Bank defines Central Africa as the Central African Republic, Chad, the Democratic Republic of the Congo, the Republic of the Congo, Equatorial Guinea, and Gabon. Middle Africa is an analogous term used by the United Nations in its geoscheme for Africa. It includes the same countries as the African Development Bank's definition, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steatocranus
''Steatocranus'' is a genus of small rheophilic cichlids mostly native to the Congo River Basin in DR Congo/Congo Brazzaville, although one species, '' S. irvinei'', is restricted to the Volta River in Ghana and Burkino Faso, and it belongs in a separate genus.Dunz, A.R., and Schliewen, U.K. (2013). Molecular phylogeny and revised classification of the haplotilapiine cichlid fishes formerly referred to as “Tilapia”. Molecular Phylogenetics and Evolution, online 29 March 2013. doi:10.1016/j.ympev.2013.03.015 There are also at least 10 undescribed species in the Congo River basin awaiting scientific description. The fish in this genus all have relatively reduced swim bladder function. The name ''Steatocranus'' refers to the fatty deposit on the forehead of most species. Two species, '' S. casuarius'' (also known as the lionhead or buffalohead cichlid) and '' S. tinanti'' are relatively common in the aquarium trade. As for other cichlids brood care is highly developed and bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
