Dioecious in the context of "Actinidia"

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⭐ Core Definition: Dioecious

Dioecy (/dˈsi/ dy-EE-see; from Ancient Greek διοικία dioikía 'two households'; adj. dioecious, /dˈʃ(i)əs/ dy-EE-sh(ee-)əs) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is biparental reproduction. Dioecy has costs, since only the female part of 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.

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Dioecious in the context of Amaranth

Amaranthus is a cosmopolitan group of more than 50 species which make up the genus of annual or short-lived perennial plants collectively known as amaranths. Some names include "prostrate pigweed" and "love lies bleeding". Some amaranth species are cultivated as leaf vegetables, pseudocereals, and ornamental plants.

Catkin-like cymes of densely packed flowers grow in summer or fall. Amaranth varies in flower, leaf, and stem color with a range of striking pigments from the spectrum of maroon to crimson and can grow longitudinally from 1 to 2.5 metres (3 to 8 feet) tall with a cylindrical, succulent, fibrous stem that is hollow with grooves and bracteoles when mature.There are approximately 75 species in the genus, 10 of which are dioecious and native to North America, and the remaining 65 are monoecious species that are endemic to every continent (except Antarctica) from tropical lowlands to the Himalayas. Members of this genus share many characteristics and uses with members of the closely related genus Celosia. Amaranth grain is collected from the genus. The leaves of some species are also eaten.

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Dioecious in the context of Pistacia lentiscus

Pistacia lentiscus (also lentisk or mastic) is a dioecious evergreen shrub or small tree of the genus Pistacia native to the Mediterranean Basin. It grows up to 4 m (13 ft) tall and is cultivated for its aromatic resin, mainly on the Greek island of Chios, around the Turkish town of Çeşme and northern parts of Iraq.

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Dioecious in the context of Cupressaceae

Cupressaceae or the cypress family is a family of conifers. The family includes 27–30 genera (17 monotypic), which include the junipers and redwoods, with about 130–140 species in total. They are monoecious, subdioecious or (rarely) dioecious trees and shrubs up to 116 m (381 ft) tall. The bark of mature trees is commonly orange- to red-brown and of stringy texture, often flaking or peeling in vertical strips, but smooth, scaly or hard and square-cracked in some species. The family reached its peak of diversity during the Mesozoic era.

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Dioecious in the context of Evolution of sexual reproduction

Sexually reproducing animals, plants, fungi and protists are thought to have evolved from a common ancestor that was a single-celled eukaryotic species. Sexual reproduction is widespread in eukaryotes, though a few eukaryotic species have secondarily lost the ability to reproduce sexually, such as Bdelloidea, and some plants and animals routinely reproduce asexually (by apomixis and parthenogenesis) without entirely having lost sex. The evolution of sexual reproduction contains two related yet distinct themes: its origin and its maintenance. Bacteria and Archaea (prokaryotes) have processes that can transfer DNA from one cell to another (conjugation, transformation, and transduction), but it is unclear if these processes are evolutionarily related to sexual reproduction in Eukaryotes. In eukaryotes, true sexual reproduction by meiosis and cell fusion is thought to have arisen in the last eukaryotic common ancestor, possibly via several processes of varying success, and then to have persisted.

Since hypotheses for the origin of sex are difficult to verify experimentally (outside of evolutionary computation), most current work has focused on the persistence of sexual reproduction over evolutionary time. The maintenance of sexual reproduction (specifically, of its dioecious form) by natural selection in a highly competitive world has long been one of the major mysteries of biology, since both other known mechanisms of reproduction – asexual reproduction and hermaphroditism – possess apparent advantages over it. Asexual reproduction can proceed by budding, fission, or spore formation and does not involve the union of gametes, which accordingly results in a much faster rate of reproduction compared to sexual reproduction, where 50% of offspring are males and unable to produce offspring themselves. In hermaphroditic reproduction, each of the two parent organisms required for the formation of a zygote can provide either the male or the female gamete, which leads to advantages in both size and genetic variance of a population.

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Dioecious in the context of Cycad

Cycads /ˈskædz/—constituting the division Cycadophyta—are seed plants with a stout, woody cylindrical trunk with a crown of large, hard, stiff, evergreen and usually pinnate (feather-shaped) leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow slowly and have long lifespans. They superficially resemble palms or ferns, but are not closely related to either group. Cycads are gymnosperms. Cycads have specialized pollinators, usually a specific beetle, and more rarely a thrips or a moth.

Both male and female cycads bear cones (strobili) containing their seeds, somewhat resembling conifer cones. Cycads fix nitrogen in association with cyanobacteria living in the plants' roots. Some species are used as narcotics, while in Vanuatu the plant symbolizes peace and appears on the national flag. Cycads all over the world are in decline, with four species on the brink of extinction and seven species each with fewer than 100 plants left in the wild.

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Dioecious in the context of Tagua

Phytelephas is a genus containing six known species of dioecious palms (family Arecaceae), occurring from southern Panama along the Andes to Ecuador, Bolivia, Colombia, northwestern Brazil, and Peru. They are commonly known as ivory palms, ivory-nut palms or tagua palms (/ˈtɑːɡwə, ˈtæɡ-/); the scientific name Phytelephas means "plant ivory" or more literally, "plant elephant". This and the first two of the common names refer to the very hard white endosperm of their seeds (tagua nuts or jarina seeds), which resembles elephant ivory.

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Dioecious in the context of Ancylostoma duodenale

Ancylostoma duodenale is a species of the roundworm genus Ancylostoma. It is a parasitic nematode worm and commonly known as the Old World hookworm. It lives in the small intestine especially the jejunum of definitive hosts, generally humans, where it is able to mate and mature. Ancylostoma duodenale and Necator americanus are the two human hookworm species that are normally discussed together as the cause of hookworm infection. They are dioecious. Ancylostoma duodenale is abundant throughout the world, including Southern Europe, North Africa, India, China, Southeast Asia, some areas in the United States, the Caribbean, and South America.

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Dioecious in the context of Pandanus

Pandanus is a genus of monocots with about 578 accepted species. They are palm-like, dioecious trees and shrubs native to the Old World tropics and subtropics. Common names include pandan, screw palm and screw pine. The genus is classified in the order Pandanales, family Pandanaceae, and is the largest in the family.

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