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Araguaian River Dolphin
The Araguaian river dolphin or Araguaian boto (''Inia araguaiaensis'') is a South American river dolphin population native to the Araguaia–Tocantins basin of Brazil. Discovery and species recognition The recognition of ''I. araguaiaensis'' as a distinct species is still debated. It was originally distinguished from the Amazon river dolphin (''Inia geoffrensis'') in January 2014 on the basis of nuclear microsatellite and mitochondrial DNA data as well as differences in skull morphology (it generally has a wider skull). It also differs from the Amazon and Bolivian river dolphins in the number of teeth per hemimandible (24–28 versus 25–29 and 31–35, respectively). However, ''I. araguaiaensis'' is still not recognized as a separate species by the Committee on Taxonomy of the Society for Marine Mammalogy, the largest international association of marine mammal scientists in the world. The Committee made these comments regarding the decision to not include ''I. araguaiaensis' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cantão
Cantão is a tropical forest ecosystem located in the central Araguaia river basin, the southeastern edge of the Amazon biome, in the Brazilian state of Tocantins. It is one of the biologically richest areas of the eastern Amazon, with over 700 species of birds, nearly 300 species of fish (more than in all of Europe), and large populations of endangered species such as the giant otter and the black cayman. About 90% of the Cantão ecosystem is protected within Cantão State Park. Ecological importance Due to its geographical location and topography, the Cantão ecosystem combines several unique features that contribute to its high biodiversity and productivity: *It is located at the ecotone between the cerrado and Amazon biomes of Brazil. The cerrado has the highest biodiversity of all the world's savannas, and the Amazon has the highest rainforest diversity. At the Cantão region, this ecotone is particularly sharp, resulting in species from both biomes coexisting within a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Echolocation
Echolocation, also called bio sonar, is a biological sonar used by several animal species. Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects. Echolocation is used for navigation, foraging, and hunting in various environments. Echolocating animals include some mammals (most notably Laurasiatheria) and a few birds, especially some bat species and odontocetes (toothed whales and dolphins), but also in simpler forms in other groups such as shrews, and two cave-dwelling bird groups, the so-called cave swiftlets in the genus ''Aerodramus'' (formerly ''Collocalia'') and the unrelated oilbird ''Steatornis caripensis''. Early research The term ''echolocation'' was coined in 1938 by the American zoologist Donald Griffin, who, with Robert Galambos, first demonstrated the phenomenon in bats. As Griffin described in his book, the 18th century I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baiji
The baiji (; IPA: ; ''Lipotes vexillifer'', ''Lipotes'' meaning "left behind" and ''vexillifer'' "flag bearer") is a possibly extinct species of freshwater dolphin native to the Yangtze river system in China. It is thought to be the first dolphin species driven to extinction due to the impact of humans. This dolphin is listed as “critically endangered: possibly extinct” by the IUCN, has not been seen in 20 years, and several surveys of the Yangtze have failed to find it. In China, the species is also called the Chinese river dolphin, Yangtze river dolphin, Yangtze dolphin and whitefin dolphin. Nicknamed the "Goddess of the Yangtze" (), it was regarded as the goddess of protection by local fishermen and boatmen. It is not to be confused with the Chinese white dolphin (''Sousa chinensis'') or the finless porpoise (''Neophocaena phocaenoides''). The baiji population declined drastically in decades as China industrialized and made heavy use of the river for fishing, transportat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence. More than 99% of all species that ever lived on Earth, amounting to over five billion species, are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryote globally, and possibly many times more if microorganisms, like bacteria, are included. Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, dodos, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
La Plata dolphin
The La Plata dolphin, franciscana or toninha (''Pontoporia blainvillei'') is a species of dolphin found in coastal Atlantic waters of southeastern South America. It is a member of the river dolphin group and the only one that lives in the ocean and saltwater estuaries, rather than inhabiting exclusively freshwater systems. Commercialized areas that create agricultural runoffs and industrialized zones can affect the health of the La Plata dolphin, especially in regards to their contributions of waste and pollution, which can lead to habitat degradation and poisoned food among other concerns. Taxonomy The La Plata dolphin is the only species in its genus, ''Pontoporia'', and is often placed in its own family, Pontoporiidae. It was first described by Paul Gervais and Alcide d'Orbigny in 1844 (the species epithet ''blainvillei'' commemorates the French zoologist Henri Marie Ducrotay de Blainville). The La Plata dolphin is also widely known as the ''Franciscana'' (the Argentine a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bolivian river dolphin
The Bolivian river dolphin (''Inia boliviensis'') is a species of the genus ''Inia''. Taxonomy Bolivian river dolphins were discovered by the Western world in 1832 by French researcher Alcide d'Orbigny. The Bolivian river dolphin was briefly thought to be a subspecies (as ''I. geoffrensis boliviensis)'' of the Amazonian river dolphin, ''Inia geoffrensis'', but differences in body structure and the isolation of the Bolivian river dolphin led to it being classified as its own species in 2012. In a study conducted in 2015, it was also noted that any gene flow between ''I. geoffrensis'' (downstream) and ''I. boliviensis'' (upstream) would be a one way path flowing from upstream to downstream due to the Teotônio waterfall between them. Despite any gene flow, these populations would also remain morphologically different from each other due to the differences in the environment in which they reside. Differences in seasonal water depth and speed would result in morphologically different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amazon river dolphin
The Amazon river dolphin (''Inia geoffrensis''), also known as the boto, bufeo or pink river dolphin, is a species of toothed whale classified in the family Iniidae. Three subspecies are currently recognized: ''I. g. geoffrensis'' (Amazon river dolphin), ''I. g. boliviensis'' (Bolivian river dolphin) and ''I. g. humboldtiana'' (Orinoco river dolphin) while position of Araguaian river dolphin (''I. araguaiaensis'') within the clade is still unclear. The three subspecies are distributed in the Amazon basin, the upper Madeira River in Bolivia, and the Orinoco basin, respectively. The Amazon river dolphin is the largest species of river dolphin, with adult males reaching in weight, and in length. Adults acquire a pink color, more prominent in males, giving it its nickname "pink river dolphin". Sexual dimorphism is very evident, with males measuring 16% longer and weighing 55% more than females. Like other toothed whales, they have a melon, an organ that is used for bio sonar. The d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inia
''Inia'' is a genus of river dolphins from South America containing one to four species. Taxonomy The genus was described by Alcide d'Orbigny in 1834 when ''Delphinus geoffrensis'', described by Henri Marie Ducrotay de Blainville in 1817, was recognized to be a unique taxon. A 1998 classification listed a single species, ''Inia geoffrensis'', in the genus ''Inia'', with three recognized subspecies. Most of the scientific community accepted this single species classification, as does the IUCN. As of 2016 the Committee on Taxonomy of the Society for Marine Mammalogy considers the genus ''Inia'' to contain one species with only two subspecies: the Bolivian (''I. g. boliviensis'') and the Amazon (''I. g. geoffrensis)'' subspecies. In 2014, the population in the Araguaia-Tocantins basin was proposed to define an additional species, ''Inia araguaiaensis'', but this remains debated. The American Society of Mammalogists recognizes the highest number of species at four, although this i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Asian River Dolphin
South Asian river dolphins are toothed whales in the genus ''Platanista'', which inhabit fresh water habitats in the northern Indian subcontinent. They were historically considered to be one species (''P. gangetica'') with the Ganges river dolphin and the Indus river dolphin being subspecies (''P. g. gangetica'' and ''P. g. minor'' respectively). Genetic and morphological evidence in 2021 has shown them to be separate species. The Ganges and Indus river dolphins are estimated to have diverged 550,000 years ago. They are the only living members of the family Platanistidae and the superfamily Platanistoidea. Fossils of ancient relatives date to the late Oligocene. South Asian river dolphins are small but stocky cetaceans with long snouts or rostra, broad flippers, and small dorsal fins. They have several unusual features. Living in murky river waters, their eyes are tiny and lensless, relying instead on echolocation for navigation. The skull has large crests over the melon, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amazon River
The Amazon River (, ; es, Río Amazonas, pt, Rio Amazonas) in South America is the largest river by discharge volume of water in the world, and the disputed longest river system in the world in comparison to the Nile. The headwaters of the Apurímac River on Nevado Mismi had been considered for nearly a century as the Amazon basin's most distant source, until a 2014 study found it to be the headwaters of the Mantaro River on the Cordillera Rumi Cruz in Peru. The Mantaro and Apurímac rivers join, and with other tributaries form the Ucayali River, which in turn meets the Marañón River upstream of Iquitos, Peru, forming what countries other than Brazil consider to be the main stem of the Amazon. Brazilians call this section the Solimões River above its confluence with the Rio Negro forming what Brazilians call the Amazon at the Meeting of Waters ( pt, Encontro das Águas) at Manaus, the largest city on the river. The Amazon River has an average discharge of about – ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pará River
The Pará River (), also called Parauaú River, Jacaré Grande River, Marajó River Channel, Macacos River Channel, Ribeirão Santa Maria, Santa Maria River Channel and Bocas Bay, is a watercourse and immense Estuary, estuarine complex that functions as a canal between the rivers Amazon River, Amazon (Amazon delta), Tocantins River, Tocantins, Campina Grande (or Pacajá River, Portel Bay) and Marajó Bay, in addition to numerous other smaller rivers. It can also be considered a distributary channel of the Tocantins River. It is located in the state of Pará, Brazil. It presents muddy and turbid waters, rich in sediments originating from its source rivers. Runs for approximately , around the west and south of the island of Marajó. Belém, the state capital of Pará, is located near the south bank of the river. Previously academic research has come to consider this watercourse as a distributary channel of the Amazon River. However, this statement is currently considered unlikel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vicariance
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow. Various geographic changes can arise such as the movement of continents, and the formation of mountains, islands, bodies of water, or glaciers. Human activity such as agriculture or developments can also change the distribution of species populations. These factors can substantially alter a region's geography, resulting in the separation of a species population into isolated subpopulations. The vicariant populations then undergo genetic changes as they become subjected to different selective pressures, experience genetic drift, and accumulate different mutations in the separated populations' gene pools. The barriers prevent the exchange of genetic information between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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