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Iteroparity
Semelparity and iteroparity are two contrasting reproductive strategies available to living organisms. A species is considered semelparous if it is characterized by a single reproductive episode before death, and iteroparous if it is characterized by multiple reproductive cycles over the course of its lifetime. Iteroparity can be further divided into continuous iteroparity (primates including humans and chimpanzees) and seasonal iteroparity (birds, dogs, etc.) Some botanists use the parallel terms monocarpy and polycarpy. (See also plietesials.) In truly semelparous species, death after reproduction is part of an overall strategy that includes putting all available resources into maximizing reproduction, at the expense of future life (see § Trade-offs). In any iteroparous population there will be some individuals who die between their first and second reproductive episodes, but unless this is part of a syndrome of programmed death after reproduction, this would not be called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fecundity
Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to produce offspring, measured by the number of gametes (eggs), seed set, or asexual propagules. Superfecundity refers to an organism's ability to store another organism's sperm (after copulation) and fertilize its own eggs from that store after a period of time, essentially making it appear as though fertilization occurred without sperm (i.e. parthenogenesis). Human demography Human demography considers only human fecundity, at its culturally differing rates, while population biology studies all organisms. The term ''fecundity'' in population biology is often used to describe the rate of offspring production after one time step (often annual). In this sense, fecundity may include both birth rates and survival of young to that time step. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oncorhynchus Nerka 2
''Oncorhynchus'' is a genus of fish in the family Salmonidae; it contains the Pacific salmon and Pacific trout. The name of the genus is derived from the Greek ὄγκος (ónkos, “lump, bend”) + ῥύγχος (rhúnkhos, “snout”), in reference to the hooked snout (the "kype") that the males develop during mating season. Range Salmon and trout with native ranges in waters draining to the Pacific Ocean are members of the genus. Their range extends from Beringia southwards, roughly to Taiwan in the west and Mexico to the east. In North America, some subspecies of '' O. clarkii'' are native in the Rocky Mountains and Great Basin, while others are native to the Rio Grande and western tributaries of the Mississippi River Basin which drain to the Gulf of Mexico, rather than to the Pacific. Several species of ''Oncorhynchus'' have been introduced into non-native waters around the globe, establishing self-sustaining wild populations. The six Pacific salmons of ''Oncorhy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monocarpy
Monocarpic plants are those that flower and set seeds only once, and then die. The term is derived from Greek (''mono'', "single" + ''karpos'', "fruit" or "grain"), and was first used by Alphonse de Candolle. Other terms with the same meaning are '' hapaxanth'' and ''semelparous''. The antonym is polycarpic, a plant that flowers and sets seeds many times during its lifetime; the antonym of semelparous is ''iteroparous''. Plants which flower en masse (gregariously) before dying are known as plietesials. The term ''hapaxanth'' is most often in conjunction with describing some of the taxa of Arecaceae (palms) and some species of bamboo, but rarely used otherwise; its antonym is ''pleonanth''. This was first used by Alexander Braun. Monocarpic plants are not necessarily annuals, because some monocarpic plants can live a number of years before they will flower. In some monocarpic plants, flowering signals senescence, while in others the production of fruits and seeds causes changes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oncorhynchus
''Oncorhynchus'' is a genus of fish in the family Salmonidae; it contains the Pacific salmon and Pacific trout. The name of the genus is derived from the Greek ὄγκος (ónkos, “lump, bend”) + ῥύγχος (rhúnkhos, “snout”), in reference to the hooked snout (the " kype") that the males develop during mating season. Range Salmon and trout with native ranges in waters draining to the Pacific Ocean are members of the genus. Their range extends from Beringia southwards, roughly to Taiwan in the west and Mexico to the east. In North America, some subspecies of '' O. clarkii'' are native in the Rocky Mountains and Great Basin, while others are native to the Rio Grande and western tributaries of the Mississippi River Basin which drain to the Gulf of Mexico, rather than to the Pacific. Several species of ''Oncorhynchus'' have been introduced into non-native waters around the globe, establishing self-sustaining wild populations. The six Pacific salmons of ''Oncor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capelin
The capelin or caplin (''Mallotus villosus'') is a small forage fish of the smelt family found in the North Atlantic, North Pacific and Arctic oceans. In summer, it grazes on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat a great deal of krill and other crustaceans. Among others, whales, seals, Atlantic cod, Atlantic mackerel, squid and seabirds prey on capelin, in particular during the spawning season while the capelin migrate south. Capelin spawn on sand and gravel bottoms or sandy beaches at the age of two to six years. When spawning on beaches, capelin have an extremely high post-spawning mortality rate which, for males, is close to 100%. Males reach in length, while females are up to long. They are olive-coloured dorsally, shading to silver on sides. Males have a translucent ridge on both sides of their bodies. The ventral aspects of the males iridesce reddish at the time of spawn. Capelin migration Capelin populations in the Barents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Labord's Chameleon
Labord's chameleon (''Furcifer labordi'') is a semelparous species of chameleon, a lizard in the family Chamaeleonidae. The species is endemic to Madagascar. Etymology The specific name, ''labordi'', is in honor of French adventurer Jean Laborde. Geographic range Laborde's chameleon is associated with spiny and deciduous forests in the south-west regions of Madagascar. Life cycle Like other ''Furcifer'' species ('' F. antimena'', '' F. lateralis''), ''F. labordi'' has an obligate year-long lifecycle. It lives for only about 4 to 5 months, making it the shortest lifespan ever recorded for a four-legged vertebrate. In their natural habitat, eggs hatch with the first rains in November. Their initial growth is rapid, and adulthood is reached by January, at which time they breed. By late February or early March, females have deposited the eggs which will hatch the next year, and the entire population dies until the next hatching. No other tetrapod has exhibited such a short life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polycarpy
Polycarpic plants are those that flower and set seeds many times before dying. A term of identical meaning is pleonanthic and iteroparous. Polycarpic plants are able to reproduce multiple times due to at least some portion of its meristems being able to maintain a vegetative state in some fashion so that it may reproduce again. This type of reproduction seems to be best suited for plants who have a fair amount of security in their environment as they do continuously reproduce. Generally, in reference to life-history theory, plants will sacrifice their ability in one regard to improve themselves in another regard, so for polycarpic plants that may strive towards continued reproduction, they might focus less on their growth. However, these aspects may not necessarily be directly correlated and some plants, notably invasive species, do not follow this general trend and actually show a fairly long lifespan with frequent reproduction. To an extent, there does seem to be an importance of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R/K Selection Theory
In ecology, ''r''/''K'' selection theory relates to the selection of combinations of traits in an organism that trade off between quantity and quality of offspring. The focus on either an increased quantity of offspring at the expense of individual parental investment of ''r''-strategists, or on a reduced quantity of offspring with a corresponding increased parental investment of ''K''-strategists, varies widely, seemingly to promote success in particular environments. The concepts of quantity or quality offspring are sometimes referred to as "cheap" or "expensive", a comment on the expendable nature of the offspring and parental commitment made. The stability of the environment can predict if many expendable offspring are made or if fewer offspring of higher quality would lead to higher reproductive success. An unstable environment would encourage the parent to make many offspring, because the likelihood of all (or the majority) of them surviving to adulthood is slim. In contrast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are involved in a wide range of physiological processes, including stress response, immune response, and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte levels, and behavior. Some common naturally occurring steroid hormones are cortisol (), corticosterone (), cortisone () and aldosterone (). (Note that cortisone and aldosterone are isomers.) The main corticosteroids produced by the adrenal cortex are cortisol and aldosterone. Classes * Glucocorticoids such as cortisol affect carbohydrate, fat, and protein metabolism, and have anti-inflammatory, immunosuppressive, anti-proliferative, and vasoconstrictive effects. Anti-inflammatory effects are mediated by blocking the action of inflam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastrointestinal Bleeding
Gastrointestinal bleeding (GI bleed), also called gastrointestinal hemorrhage (GIB), is all forms of bleeding in the gastrointestinal tract, from the mouth to the rectum. When there is significant blood loss over a short time, symptoms may include vomiting red blood, vomiting black blood, bloody stool, or black stool. Small amounts of bleeding over a long time may cause iron-deficiency anemia resulting in feeling tired or heart-related chest pain. Other symptoms may include abdominal pain, shortness of breath, pale skin, or passing out. Sometimes in those with small amounts of bleeding no symptoms may be present. Bleeding is typically divided into two main types: upper gastrointestinal bleeding and lower gastrointestinal bleeding. Causes of upper GI bleeds include: peptic ulcer disease, esophageal varices due to liver cirrhosis and cancer, among others. Causes of lower GI bleeds include: hemorrhoids, cancer, and inflammatory bowel disease among others. Diagnosis typ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichnotropis
''Ichnotropis'' is a genus of African lizards in the family Lacertidae. Species in the genus ''Ichnotropis'' are commonly called rough-scaled lizards."''Ichnotropis'' ". The Reptile Database. www.reptile-database.org. Species The following six species are recognized as being valid. *''Ichnotropis bivittata'' Bocage, 1866 - Angolan rough-scaled lizard *''Ichnotropis capensis'' ( A. Smith, 1838) - Cape rough-scaled lizard, ornate rough-scaled lizard, Smith's rough-scaled sand lizard *''Ichnotropis chapini'' K.P. Schmidt, 1919 *''Ichnotropis grandiceps'' Broadley, 1967 - Caprivi rough-scaled lizard *''Ichnotropis microlepidota'' Marx, 1956 - Marx's rough-scaled lizard *''Ichnotropis tanganicana'' Boulenger, 1917 - Tanzanian rough-scaled lizard, ''Nota bene'': A binomial authority in parentheses indicates that the species was originally described in a genus other than ''Ichnotropis''. References Further reading * Boulenger GA (1887). ''Catalogue of the Lizards in the British Mus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobelia Telekii
''Lobelia telekii'' is a species of flowering plant in the family Campanulaceae, that is found only in the alpine zones of Mount Kenya, Mount Elgon, and the Aberdare Mountains of East Africa. It occurs at higher altitudes on well-drained sloped hillsides. It is a Biological reproduction#Other types of reproductive strategies, semelparous species, putting all its reproductive effort into producing single large inflorescence up to tall, and then dying. Inflorescences of ''L. telekii'' also possesses a large pith-volume for internal water storage and marcescent foliage which could provide insulation. It secretes a polysaccharide into this reservoir, which may be useful for its survival in the cold climate. The plant is named after the Austro-Hungarian explorer, Count Sámuel Teleki (explorer), Sámuel Teleki. ''L. telekii'' plants usually consist of a single rosette, which grows for several decades, flowers once, and then dies. However, a very small number of plants have multi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
