|
XO Sex-determination System
The XO sex-determination system (sometimes referred to as X0 sex-determination system) is a system that some species of insects, arachnids, and mammals (not including humans) use to determine the sex of offspring. In this system, there is only one sex chromosome, referred to as X. Males only have one X chromosome (XO), while females have two (XX). The letter O (sometimes a zero) signifies the lack of a Y chromosome. Maternal gametes always contain an X chromosome, so the sex of the animals' offspring depends on whether a sex chromosome is present in the male gamete. Its sperm normally contains either one X chromosome or no sex chromosomes at all. This system determines the sex of offspring among: * Most arachnidsBull, James J.; ''Evolution of sex determining mechanisms''; p. 17 with the exception of mites where a small majority are haplodiploid * Almost all apterygote and Paleopteran insects (e.g., dragonflies, silverfish) * Most exopterygote insects (e.g., grasshoppe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Critique Of The Theory Of Evolution Fig 060
Critique is a method of disciplined, systematic study of a written or oral discourse. Although critique is frequently understood as fault finding and negative judgment, Rodolphe Gasché (2007''The honor of thinking: critique, theory, philosophy''pp. 12–13 quote: it can also involve merit recognition, and in the philosophical tradition it also means a methodical practice of doubt. The contemporary sense of critique has been largely influenced by the Enlightenment critique of prejudice and authority, which championed the emancipation and autonomy from religious and political authorities. The term ''critique'' derives, via French, from the Greek word (), meaning "the faculty of judging", that is, discerning the value of persons or things. Critique is also known as major logic, as opposed to minor logic or dialectics. Critique in philosophy Philosophy is the application of critical thought, and is the disciplined practice of processing the ''theory/praxis problem''. In philoso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustacean
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthropods including decapods (shrimps, prawns, crabs, lobsters and crayfish), seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods (insects and entognathans) emerged deep in the Crustacean group, with the completed pan-group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans ( oligostracans and multicrustaceans). The 67,000 described species range in size from '' Stygotantulus stocki'' at , to the Japanese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caenorhabditis Elegans
''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a Hybrid word, blend of the Greek ''caeno-'' (recent), ''rhabditis'' (rod-like) and Latin ''elegans'' (elegant). In 1900, Émile Maupas, Maupas initially named it ''Rhabditidae, Rhabditides elegans.'' Günther Osche, Osche placed it in the subgenus ''Caenorhabditis'' in 1952, and in 1955, Ellsworth Dougherty, Dougherty raised ''Caenorhabditis'' to the status of genus. ''C. elegans'' is an unsegmented pseudocoelomate and lacks respiratory or circulatory systems. Most of these nematodes are hermaphrodites and a few are males. Males have specialised tails for mating that include spicule (nematode), spicules. In 1963, Sydney Brenner proposed research into ''C. elegans,'' primarily in the area of neuronal development. In 1974, he began research into the molecular biology, molecular and developmental ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Model Organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Model organisms are widely used to research human disease when human experimentation would be unfeasible or unethical. This strategy is made possible by the common descent of all living organisms, and the conservation of metabolic and developmental pathways and genetic material over the course of evolution. Research using animal models has been central to most of the achievements of modern medicine. It has contributed most of the basic knowledge in fields such as human physiology and biochemistry, and has played significant roles in fields such as neuroscience and infectious disease. The results have included the near- eradication of polio and the development of organ transplantation, and have benefited both humans and animals. From 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermaphrodite
A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many taxonomic groups of animals, primarily invertebrates, are hermaphrodites, capable of producing viable gametes of both sexes. In the great majority of tunicates, mollusks, and earthworms, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the female or male. Hermaphroditism is also found in some fish species, but is rare in other vertebrate groups. Most hermaphroditic species exhibit some degree of self-fertilization. The distribution of self-fertilization rates among animals is similar to that of plants, suggesting that similar pressures are operating to direct the evolution of selfing in animals and plants. A rough estimate of the number of hermaphroditic animal species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tokunoshima Spiny Rat
The Tokunoshima spiny rat (''Tokudaia tokunoshimensis'') is a rodent found only on the island of Tokunoshima in the Satsunan Islands of Japan. Due to its small habitat, it is considered endangered. It is commonly found in the secondary and primary subtropical moist broadleaf forests of this island. The karyotype has an odd diploid number, 2n = 45. Like its relative '' T. osimensis'', it is one of the few mammals that lack a Y chromosome and ''SRY'' gene. The species is threatened by deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ... and predation by feral cats and dogs. See also * '' Ellobius lutescens'' * '' Ellobius tancrei'' References Tokudaia Endemic mammals of Japan Endemic fauna of the Ryukyu Islands Mammals described in 2006 {{Murinae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ryukyu Spiny Rat
The Ryukyu spiny rat (''Tokudaia osimensis'') is a species of rodent in the family Muridae. Endemic to Amami Ōshima island in the Amami Islands of the Ryukyu Islands, Ryukyu archipelago of Japan, its natural habitat is subtropical moist broadleaf forest. The karyotype has an odd diploid number, 2n = 25. Like its relative ''Tokudaia tokunoshimensis, T. tokunoshimensis'', it has lost its Y chromosome and SRY gene, ''SRY'' gene. The species is threatened by habitat destruction and habitat fragmentation, fragmentation, predation by feral cats and dogs and introduced species, introduced Herpestes auropunctatus, mongooses, and competition with introduced black rats. See also * ''Ellobius lutescens'' * ''Ellobius tancrei'' References Y-chromosome - Will it or will it not, hold on? Rats of Asia Endemic mammals of Japan Endemic fauna of the Ryukyu Islands Endangered fauna of Asia Tokudaia Mammals described in 1934 Taxonomy articles created by Polbot {{Murinae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gambian Epauletted Fruit Bat
The Gambian epauletted fruit bat (''Epomophorus gambianus'') is a species of megabat in the family Pteropodidae. It is found in Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Democratic Republic of the Congo, Ivory Coast, Ethiopia, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Niger, Nigeria, Senegal, Sierra Leone, South Sudan, Sudan, and Togo. Its natural habitats are subtropical or tropical dry forests and savanna. Populations of epauletted fruit bats are threatened by pesticides on fruit, human disturbance and over-collecting in the past. However, the number one reason it may be threatened is habitat destruction. Mostly found in Africa, these creatures have grayish-brown color fur with a white patch at the base of their ear in both males and females. These fruit bats are also very noisy creatures. In the context of mating behavior (see "Reproduction" below), adult males may hang from perches and perform a calling-display during which they utter a modera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peters's Epauletted Fruit Bat
The Peters's epauletted fruit bat (''Epomophorus crypturus'') is a species of megabat in the family Pteropodidae. It is found in Angola, Botswana, Democratic Republic of the Congo, Eswatini, Malawi, Mozambique, Namibia, Tanzania, Zambia, and Zimbabwe. Its natural habitat is in riverine or evergreen forest, or moist woodland, where there are fruit-bearing trees. Taxonomy It was species description, described as a new species in 1852 by German naturalist Wilhelm Peters. Peters collected the holotype in "Tette" in Mozambique during an expedition that occurred from 1842 to 1848. Description Individuals have a forearm length ranging from and weigh . It consumes plant matter such as fruit and nectar. For reproduction, the typical litter size is one, though twins are perhaps possible, if very rare. Newborns are altricial at birth, with eyes closed and sparse fur. Newborns weigh around . Births likely occur around September, and it has been suggested that females give birth once per yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Franquet's Epauletted Fruit Bat
Franquet's epauletted fruit bat (''Epomops franqueti'') is a species of megabat in the family Pteropodidae, and is one of three different species of epauletted bats. Franquet's epauletted fruit bat has a range of habitats, varying from Subsaharan forest to equatorial tropics. Range and habitat Franquet's epauletted fruit bat ranges from Ivory Coast to South Sudan and south to Angola and Zambia. Specifically, it is found in Angola, Benin, Cameroon, Central African Republic, Republic of the Congo, Democratic Republic of the Congo, Ivory Coast, Ghana, Nigeria, Rwanda, South Sudan, Tanzania, Togo, Uganda, and possibly Zambia. Reports of this species from Equatorial Guinea appear to be erroneous. Its natural habitat are subtropical or tropical dry, moist lowland, and mangrove forests, subtropical or tropical swamps, and dry savanna. Description The Franquet's epauletted fruit bat was first described by Robert F. Tomes in 1860 and classified as ''Epomophorus francqueti'' from a spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buettikofer's Epauletted Fruit Bat
Buettikofer's epauletted fruit bat (''Epomops buettikoferi'') is a species of megabat in the family Pteropodidae. It is found in Ivory Coast, Ghana, Guinea, Guinea-Bissau, Liberia, Nigeria, Senegal, and Sierra Leone. Its natural habitats are subtropical or tropical moist lowland forest and savanna. Taxonomy and etymology It was described as a new species in 1899 by German zoologist Paul Matschie. Matschie placed it in the genus Epomophorus, naming it ''Epomophorus büttikoferi''. The holotype was found in Schlieffelinsville, Liberia, along the Junk River. Matschie named the new species after Dr. Johann Büttikofer, who had conducted several scientific expeditions to Liberia. In 1965, Kuhn published that it was a subspecies of the Franquet's epauletted fruit bat (''Epomops franqueti''). This was refuted in 1975 by Bergmans, who reported that the Buettikofer's epauletted fruit bat differs significantly from Franquet's epauletted fruit bat in its morphology, warranting that they rem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
