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Hybrid Organisms
In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different varieties, subspecies, species or genera through sexual reproduction. Generally, it means that each cell has genetic material from two different organisms, whereas an individual where some cells are derived from a different organism is called a chimera. Hybrids are not always intermediates between their parents such as in blending inheritance (a now discredited theory in modern genetics by particulate inheritance), but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are. Species are reproductively isolated by strong barriers to hybridization, which include genetic and morpholog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pollen
Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male Conifer cone, cone to the female cone of gymnosperms. If pollen lands on a compatible pistil or female cone, it Germination, germinates, producing a pollen tube that transfers the sperm to the ovule containing the female gametophyte. Individual pollen grains are small enough to require magnification to see detail. The study of pollen is called palynology and is highly useful in paleoecology, paleontology, archaeology, and Forensic science, forensics. Pollen in plants is used for transferring Ploidy#Haploid and monoploid, haploid male genetic ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cultivar
A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root and stem cuttings, offsets, grafting, micropropagation, tissue culture, or carefully controlled seed production. Most cultivars arise from deliberate human genetic engineering, manipulation, but some originate from wild plants that have distinctive characteristics. Cultivar names are chosen according to rules of the International Code of Nomenclature for Cultivated Plants (ICNCP), and not all cultivated plants qualify as cultivars. Horticulturists generally believe the word ''cultivar''''Cultivar'' () has two meanings, as explained in ''#Formal definition, Formal definition'': it is a classification category and a taxonomic unit within the category. When referring to a taxon, the word does not apply to an individual plant but to all plants t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breed
A breed is a specific group of breedable domestic animals having homogeneous appearance (phenotype), homogeneous behavior, and/or other characteristics that distinguish it from other organisms of the same species. In literature, there exist several slightly deviating definitions. Breeds are formed through genetic isolation and either natural adaptation to the environment or selective breeding, or a combination of the two. Despite the centrality of the idea of "breeds" to animal husbandry and agriculture, no single, scientifically accepted definition of the term exists. A breed is therefore not an objective or biologically verifiable classification but is instead a term of art amongst groups of breeders who share a consensus around what qualities make some members of a given species members of a nameable subset. Another point of view is that a breed is consistent enough in type to be logically grouped together and when mated within the group produce the same type. When bred togeth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Domesticated Plants
This is a list of plants that have been domesticated by humans. The list includes individual plant species identified by their common names as well as larger formal and informal botanical categories which include at least some domesticated individuals. Plants in this list are grouped by the original or primary purpose for which they were domesticated, and subsequently by botanical or culinary categories. Plants with more than one significant human use may be listed in multiple categories. Plants are considered domesticated when their life cycle, behavior, or appearance has been significantly altered as a result of being under artificial selection by humans for multiple generations (see the main article on domestication for more information). Thousands of distinct plant species have been domesticated throughout human history. Not all modern domesticated plant varieties can be found growing in the wild; many are actually hybrids of two or more naturally occurring species and theref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Domesticated Animals
This page gives a list of domesticated animals, also including a list of domestication of animals, animals which are or may be currently undergoing the process of domestication and animals that have an extensive relationship with humans beyond simple predation. This includes species which are semi-domesticated, undomesticated but Captive breeding, captive-bred on a commercial scale, or commonly wild-caught, at least occasionally captive-bred, and Tame animal, tameable. In order to be considered fully domesticated, most species have undergone significant Heredity, genetic, Behavior, behavioural and Morphology (biology), morphological changes from their wild ancestors, while others have changed very little from their wild ancestors despite hundreds or thousands of years of potential selective breeding. A number of factors determine how quickly any changes may occur in a species, but there is not always a desire to improve a species from its wild form. Domestication is a gradual process ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selective Breeding
Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together. Domesticated animals are known as breeds, normally bred by a professional breeder, while domesticated plants are known as varieties, cultigens, cultivars, or breeds. Two purebred animals of different breeds produce a crossbreed, and crossbred plants are called hybrids. Flowers, vegetables and fruit-trees may be bred by amateurs and commercial or non-commercial professionals: major crops are usually the provenance of the professionals. In animal breeding artificial selection is often combined with techniques such as inbreeding, linebreeding, and outcrossing. In plant breeding, similar methods are used. Charles Darwin discussed how selective breeding had been succ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wolfdog
A wolfdog is a canine produced by the mating of a domestic dog (''Canis familiaris'') with a gray wolf (''Canis lupus''), eastern wolf (''Canis lycaon''), red wolf (''Canis rufus''), or Ethiopian wolf (''Canis simensis'') to produce a hybrid. Admixture There are a range of experts who believe that they can tell the difference between a wolf, a dog, and a wolfdog, but they have been proven to be incorrect when providing their evidence before courts of law. Admixture between domestic dogs and other subspecies of gray wolves are the most common wolfdogs since dogs and gray wolves are considered the same species, are genetically very close and have shared vast portions of their ranges for millennia. Such admixture in the wild have been detected in many populations scattered throughout Europe and North America, usually occurring in areas where wolf populations have declined from human impacts and persecutions. At the same time, wolfdogs are also often bred in captivity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beefalo
Beefalo constitutes a hybrid offspring of domestic cattle (''Bos taurus''), usually a male in managed breeding programs, and the American bison (''Bison bison''), usually a female in managed breeding programs. The breed was created to combine the characteristics of both animals for beef production. Beefalo are primarily cattle in genetics and appearance, with the breed association defining a full Beefalo as one with three-eighths (37.5%) bison genetics, while animals with higher percentages of bison genetics are called bison hybrids. However, genomic analysis has found that the vast majority of Beefalo, even those considered pedigree by the breed association, have no detectable bison ancestry, with no sampled Beefalo having higher than 18% bison ancestry, with most Beefalo consisting of a mixture of taurine cattle and zebu cattle ancestry. History and genomics Accidental crosses were noticed as long ago as 1749 in the Southern states of North America, during British c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutationism
Mutationism is one of several alternatives to evolution by natural selection that have existed both before and after the publication of Charles Darwin's 1859 book ''On the Origin of Species''. In the theory, mutation was the source of novelty, creating new forms and new species, potentially instantaneously, in sudden jumps. This was envisaged as driving evolution, which was thought to be limited by the supply of mutations. Before Darwin, biologists commonly believed in saltationism, the possibility of large evolutionary jumps, including immediate speciation. For example, in 1822 Étienne Geoffroy Saint-Hilaire argued that species could be formed by sudden transformations, or what would later be called macromutation. Darwin opposed saltation, insisting on gradualism in evolution as geology's uniformitarianism. In 1864, Albert von Kölliker revived Geoffroy's theory. In 1901 the geneticist Hugo de Vries gave the name "mutation" to seemingly new forms that suddenly arose in his exp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oenothera Lamarckiana
''Oenothera glazioviana'' is a species of flowering plant in the evening primrose family known by the common names large-flowered evening-primrose and redsepal evening primrose. ''Oenothera lamarckiana'' was formerly believed to be a different species, but is now regarded as a synonym of ''Oe. glazioviana''. The plant can be found in scattered locations worldwide, mostly as an introduced species. It originated in Brazil. It has long been cultivated as an ornamental plant. In some locations it has become an invasive species. Description ''Oenothera glazioviana'' is generally a biennial herb producing an erect stem approaching in maximum height. It is roughly hairy in texture, the hairs with reddish blistering or glandular bases. The crinkly leaves are up to 15 centimeters long. The inflorescence is a showy spike of many large flowers. When in bud the long red sepals are visible. When in bloom each flower has four bright yellow petals up to 5 centimeters long which fade or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agriculture
Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to live in the cities. While humans started gathering grains at least 105,000 years ago, nascent farmers only began planting them around 11,500 years ago. Sheep, goats, pigs, and cattle were domesticated around 10,000 years ago. Plants were independently cultivated in at least 11 regions of the world. In the 20th century, industrial agriculture based on large-scale monocultures came to dominate agricultural output. , small farms produce about one-third of the world's food, but large farms are prevalent. The largest 1% of farms in the world are greater than and operate more than 70% of the world's farmland. Nearly 40% of agricultural land is found on farms larger than . However, five of every six farm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
