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Trioecious
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 theoretic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opuntia Robusta
''Opuntia robusta'', the wheel cactus, nopal tapon, or camuesa, is a species of cactus in the family Cactaceae. It is native and endemic to central and northern Mexico to within of the Arizona and New Mexico borders where it grow from on rocky slopes, open shrub lands, woodlands and mixed with other cactus and succulents. Description Plants are commonly around high, though they may grow to over high when supported. The flattened stem segments are fleshy, round and blue-grey in colour. These are up to in diameter and have the length of sharp spines up to . Yellow, sessile flowers with a fleshy base are produced on the edges of the upper stem segments. These are followed by barrel-shaped fleshy fruits which are pink or purple and up to long. ''Opuntia robusta'' has populations that are dioecious, hermaphrodite, or trioecious (containing male, female, and hermaphrodite individuals). Taxonomy The species was first formally described in 1837 in ''Enumeratio Diagnostica Cactear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buddleja Sessiliflora
''Buddleja sessiliflora'', commonly known as Rio Grande butterfly-bush or tepozán, native to southern Arizona and the lower Rio Grande Valley of Texas in the United States as well as much of central and northern Mexico excluding the Chihuahua Desert and Baja California Sur. The shrub grows in thorn savannah, forests, riparian zones, along roadsides and in disturbed areas from sea level to 2,800 m. The species was first named and described by Kunth in 1818.Kunth, in Humboldt, Bonpland, and Kunth. (1818). ''Nov. gen. sp., ed. fol.'' 2:278, ed. quar. 2:345, t184, 1818.Norman, E. M. (2000). Buddlejaceae. ''Flora Neotropica 81''. New York Botanical Garden, USA Description ''Buddleja sessiliflora'' is a trioecious shrub or small tree 1.5 – 5 m tall, the trunk reaching < 7 cm diameter, bark is yellow-brown in colour and fissured. The young branches are subquadrangular, yellowish, the youngest sections |
Buddleja Americana
''Buddleja americana'' is the most widespread of all the ''Buddleja'' species native to the Americas, its range extending south from Tamaulipas, Mexico, through Central America and much of the West Indies into South America, reaching eastward to Venezuela, westward as far as the Galapagos, and south to Bolivia. It occurs at elevations from sea level to 2500 m, in a variety of habitats, including cloud forest, mountain savanna, pine - oak forest, and rocky slopes near rivers. It also invades fields and roadsides.Norman, E. M. (2000). Buddlejaceae. ''Flora Neotropica 81'', New York Botanical Garden, USA The species was originally named and described by Linnaeus in 1753.Linnaeus, C. (1753). ''Sp. pl.'' 112. 1753. Description ''B. americana'' is a trioecious shrub, 2–5 m tall with light brown fissured bark. The young branches are sub quadrangular, and tomentose, bearing leaves which vary greatly in size, shape and indumentum. The inflorescences are 5–25 c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semimytilus Algosus
''Semimytilus algosus'' is a species of mussels. A common name for this species is Bisexual mussel, or Dwarf mussel. It is the first species where trioecy was reported in the phylum Mollusca. Size Individuals can be up to 42 mm or 50 mm in size. Reproduction The species reproduces sexually. In the past this species was described as simultaneous hermaphroditic but it was later confirmed the species is trioecious. It is believed this species evolved from a gonochoric ancestor. Occurrence Its habitat is rocky shores. The species has been found off the coasts of South Africa and is native to Chile. The species is also invasive off the coast of Angola and Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and e .... References Mytilidae {{Improve categories, d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thor Manningi
''Thor manningi'' is a species of crustacean. The common name for this species is the Manning grass shrimp. On average the life span in this species is 4 to 5 months. The species uses drag powered swimming to move from place to place. ''Thor manningi'' is a trioecious species with males, females Female (symbol: ♀) is the sex of an organism that produces the large non-motile ova (egg cells), the type of gamete (sex cell) that fuses with the male gamete during sexual reproduction. A female has larger gametes than a male. Females a ... and protandrous hermaphrodites. Individuals approaching sex change have a mixture of male and female characteristics. In this species 50% of the population are males, 49% protandric hermaphrodites, and 1% are females. References {{Taxonbar, from=Q4466234 Alpheoidea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonochorism
In biology, gonochorism is a sexual system where there are only two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochorism contrasts with simultaneous hermaphroditism but it may be hard to tell if a species is gonochoric or sequentially hermaphroditic. (e.g. Parrotfish, '' Patella ferruginea''). However, in gonochoric species individuals remain either male or female throughout their lives. Species that reproduce by thelytokous parthenogenesis and do not have males can still be classified as gonochoric. Terminology The term is derived from Greek (''gone'', generation) + (''chorizein,'' to separate). The term gonochorism originally came from German gonochorismus. Gonochorism is also referred to as unisexualism or gonochory. Evolution Gonochorism has evolved independently multiple times and is very evolutionary stable in animals. Its stability and ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coccoloba Cereifera
''Coccoloba cereifera'' is a rare species of flowering plant in the knotweed or buckwheat family Polygonaceae. The species is restricted to a single mountain, the Serra do Cipó, in southern Brazil. The species is notable for its expression of a trioecious 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 .... References cereifera Endemic flora of Brazil {{Polygonaceae-stub ... [...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] |
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 dioecious (gon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydra Viridissima
''Hydra viridissima'' is a species of cnidarian which is commonly found in still or slow-moving freshwater in the Northern temperate zone. ''Hydra viridissima'' is commonly called green hydra due to its coloration, which is due to the symbiotic green algae ''Chlorella vulgaris'' which live within its body. These creatures are typically 10 mm long and have tentacles that are about half of their length. They are strictly carnivorous and typically feed on small crustaceans, insects and annelids. ''Hydra'' are normally sessile and live on aquatic vegetation. They secrete mucous to attach to substrate using their basal disc. Anatomy ''Hydra'' are multi-cellular organisms. They are made up of two layers of epithelial cells and have a hypostome or mouth opening. Circling the mouth are tentacles that contain nematocysts or stinging cells to help in prey capture. The mouth and tentacles are called the hydranth. The rest of the ''Hydra'' is known as the column and is divided into four ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aiptasia Diaphana
''Aiptasia diaphana'', commonly known as the yellow aiptasia or glasrose, is a species of sea anemone native to shallow waters in the temperate eastern Atlantic Ocean and the Mediterranean Sea. It has been introduced into the Red Sea. Description ''Aiptasia diaphana'' is a small sea anemone with a base diameter of up to , a column height of up to and an oral disc of . The column is yellowish-brown or brownish-green, smooth and retractable. The colour is somewhat variable because symbiotic algae (zooxanthellae) are sometimes present in the tissues. The oral disc is transparent and bears, round the rim, four or five whorls of slender, pointed tentacles making a total of up to 160 tentacles. These are translucent with white bases, a distinguishing feature for this species. Distribution and habitat ''Aiptasia diaphana'' is native to the Atlantic coast of Portugal, the Canary Islands and throughout the Mediterranean Sea and has been introduced to the Red Sea. It is found on hard su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
