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Hermaphrodism
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the female or male. For example, the great majority of tunicates, pulmonate molluscs, opisthobranch, earthworms, and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also hermaphrodites. Animal species having different sexes, male and female, are called gonochoric, which is the opposite of hermaphrodite. There are also species where hermaphrodites exist alongside males (called androdioecy) or alongside females (called gynodioecy), or all three exist in the same species (called trioecy); these three systems ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snails Mating
A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastropoda that have a coiled shell that is large enough for the animal to retract completely into. When the word "snail" is used in this most general sense, it includes not just land snails but also numerous species of sea snails and freshwater snails. Gastropods that naturally lack a shell, or have only an internal shell, are mostly called ''slugs'', and land snails that have only a very small shell (that they cannot retract into) are often called '' semi-slugs''. Snails have considerable human relevance, including as food items, as pests, and as vectors of disease, and their shells are used as decorative objects and are incorporated into jewelry. The snail has also had some cultural significance, tending to be associated with lethargy. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrates
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described. Vertebrates comprise such groups as the following: * jawless fish, which include hagfish and lampreys * jawed vertebrates, which include: ** cartilaginous fish (sharks, rays, and ratfish) ** bony vertebrates, which include: *** ray-fins (the majority of living bony fish) *** lobe-fins, which include: **** coelacanths and lungfish **** tetrapods (limbed vertebrates) Extant vertebrates range in size from the frog species ''Paedophryne amauensis'', at as little as , to the blue whale, at up to . Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns. The vertebrates traditionally include the hagfish, which do not have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intersex Society Of North America
The Intersex Society of North America (ISNA) was a non-profit advocacy group founded in 1993 by Cheryl Chase to end shame, secrecy, and unwanted genital surgeries.Matthews, Karen (Oct 22, 2000). Debate Grows Over Using Surgery on Infants with Ambiguous Genitals. ''Los Angeles Times''Murrell, Nancy (October 28, 1998). Intersex group raises questions about genital surgery. ''Miami Herald''Hackford-Peer, Kim (2005). Cheryl Chase Founds the Intersex Society of North America. in ''GLBT History, 1993–2004''; 2005, p28-30, 2p Other notable members included Morgan Holmes, Max Beck, Howard (Tiger) Devore, Esther Morris Leidolf and Alice Dreger. The organization closed in June 2008,Staff report (June 28, 2008)Farewell message. via ISNA.org and has been succeeded by a number of health, civil and human rights organizations including interACT. Advocacy Physical integrity and bodily autonomy ISNA stated that newborn intersex genitals should not be operated on, unless they need to be in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Social Stigma
Social stigma is the disapproval of, or discrimination against, an individual or group based on perceived characteristics that serve to distinguish them from other members of a society. Social stigmas are commonly related to culture, gender, race, socioeconomic class, age, sexual orientation, body image, physical disability, intelligence or lack thereof, and health. Some stigma may be obvious, while others are known as concealable stigmas that must be revealed through disclosure. Stigma can also be against oneself, stemming from negatively viewed personal attributes in a way that can result in a "spoiled identity" (i.e., self-stigma). Description Stigma (plural stigmas or ''stigmata'') is a Greek word that in its origins referred to a type of marking or the tattoo that was cut or burned into the skin of people with criminal records, slaves, or those seen as traitors in order to visibly identify them as supposedly blemished or morally polluted persons. These individuals were t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intersex
Intersex people are individuals born with any of several sex characteristics including chromosome patterns, gonads, or genitals that, according to the Office of the United Nations High Commissioner for Human Rights, "do not fit typical binary notions of male or female bodies". Sex assignment at birth usually aligns with a child's anatomical sex and phenotype. The number of births with ambiguous genitals is in the range of 1:2000–1:4500 (0.022%–0.05%). Other conditions involve atypical chromosomes, gonads, or hormones. Some persons may be assigned and raised as a girl or boy but then identify with another gender later in life, while most continue to identify with their assigned sex. The number of births where the baby is intersex has been reported differently depending on who reports and which definition of intersex is used. Anne Fausto-Sterling and her co-authors suggest that the prevalence of "nondimorphic sexual development" might be as high as 1.7%. A study publis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Michael Majerus
Michael Eugene Nicolas Majerus (13 February 1954 – 27 January 2009) was a British geneticist and professor of evolution at the University of Cambridge. He was also a teaching fellow at Clare College, Cambridge. He was an enthusiast in Darwin's theory of evolution by natural selection and became a world authority in his field of insect evolutionary biology. He was widely noted for his work on moths and ladybirds and as an advocate of the science of evolution. He was also an enthusiastic educator and the author of several books on insects, evolution and sexual reproduction. He is best remembered as an ardent supporter and champion of experiments on peppered moth evolution. Biography The son of Fernand and Muriel Majerus, Michael Majerus took an early interest in insects. He got his first butterfly net at the age of four. His father, a Luxembourg national by origin, encouraged him by taking him for field trips on weekends and bringing him home specimens from his travels. He ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioecy
Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is biparental reproduction. Dioecy has costs, since only about half the population directly produces offspring. It is one method for excluding self-fertilization and promoting allogamy (outcrossing), and thus tends to reduce the expression of recessive deleterious mutations present in a population. Plants have several other methods of preventing self-fertilization including, for example, dichogamy, herkogamy, and self-incompatibility. Dioecy is a dimorphic sexual system, alongside gynodioecy and androdioecy. In zoology In zoology, dioecious species may be opposed to hermaphroditic species, meaning that an individual is either male or female, in which case the synonym gonochory is more often used. Most animal species are dioeci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gynomonoecious
Gynomonoecy is defined as the presence of both female and hermaphrodite flowers on the same individual of a plant species. It is prevalent in Asteraceae but is poorly understood. It is a monomorphic sexual system alongside monoecy, andromonoecy and trimonoecy. Occurrence This sexual system occurs in about 2.8% of flowering plants. It is present in 3% of '' Silene'' species and 23 families of flowering plants, but is most common in the daisy family, Asteraceae. About 200 of the approximately 23000 species in the Asteraceae are gynomonoecious. Evolution Gynomonoecy may be an intermediate evolutionary state between monoecy and hermaphroditism. It is also hypothesized to be the ancestor to trimonoecy. Gynomonecy evolved once in Hawaiian '' Tetramolopium''. In families like Compositae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andromonoecious
Andromonoecy is a breeding system of plant species in which male and hermaphrodite flowers are on the same plant. It is a monomorphic sexual system alongside monoecy, gynomonoecy and trimonoecy. Andromonoecy is frequent among genera with zygomorphic flowers, however it is overall rare and occurs in less than 2% of plant species. Nonetheless the breeding system has gained interest among biologists in the study of sex expression. Etymology The word andromonoecious is a combination of andr- (meaning male) and monoecious and was first used in 1877. Prevalence It is uncommon and has been estimated to occur in less than 2% of plant species. In angiosperms, it occurs in 1.7% of angiosperms making up around 4000 species in 33 families. It is common in the grass subfamily Panicoideae. Andromonoecious species * ''Cucumis melo'' subsp * '' Cucumis melo'' * '' Chaerophyllum bulbosum'' * '' Erophaca baetica'' * '' Silene tibetica'' '' Solanum'' * '' Solanum agnewiorum'' * '' S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual System
A sexual system is a pattern of sex allocation or a distribution of male and female function across organisms in a species. Terms like reproductive system and mating system have also been used as synonyms. The distinction between sexual systems is not always clear due to phenotypic plasticity. Sexual systems are viewed as a key factor for genetic variation and reproductive success, and may have also led to the origin or extinction of certain species. Interests in sexual systems go back to Darwin, who found that barnacles contain species that are androdioecious and some that are dioecious. Types of sexual systems In plants there are monomorphic sexual systems where a species has hermaphrodite, male and/or female flowers on the same plant. Monomorphic sexual systems include monoecy, gynomonoecy, andromonoecy and trimonoecy. There are also dimorphic sexual systems like dioecy, gynodioecy and androdioecy. Mixed sexual systems are where hermaphrodites coexist with s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trioecy
Trioecy, or subdioecy, is a rare sexual system characterized by the coexistence of males, females, and hermaphrodites. It has been found in both plants and animals. Trioecy is sometimes referred to as a mixed mating system alongside androdioecy and gynodioecy. Evolution of trioecy Many speculate trioecy is a transient state and is often associated with evolutionary transitioning from gynodioecy to dioecy. Other studies show that trioecious populations originated from gonochoristic ancestors which were invaded by a mutant selfing hermaphrodite, creating a trioecious population. It has been suggested that chromosomal duplication is an important part in the evolution of trioecy. Evolutionary stability Trioecy is usually viewed as evolutionarily unstable, but its exact stability is unclear. Like in brachiopod species trioecy usually breaks into androdioecy or gynodioecy. But one study found that trioecy can be stable under nucleocytoplasmic sex determination. Another theoretical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gynodioecy
Gynodioecy is a rare breeding system that is found in certain flowering plant species in which female and hermaphroditic plants coexist within a population. Gynodioecy is the evolutionary intermediate between hermaphroditism (exhibiting both female and male parts) and dioecy (having two distinct morphs: male and female). Gynodioecy is sometimes considered a mixed breeding system alongside trioecy and androdioecy. It is also considered a dimorphic sexual system alongside dioecy and androdioecy. Gynodioecy occurs as a result of a genetic mutation that inhibits a hermaphroditic plant from producing pollen, while keeping the female reproductive parts intact. Gynodioecy is extremely rare, with fewer than 1% of angiosperm species exhibiting the breeding system. Some notable taxa that exhibit a gynodioecious mating system include ''Beta vulgaris'' (wild beet), '' Lobelia siphilitica'', '' Silene'', and Lamiaceae. Evolution Gynodioecy is often referred to as the evolutionary int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
