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Animal Domestication
The domestication of animals is the mutual relationship between non-human animals and the humans who have influence on their care and reproduction. Charles Darwin recognized a small number of traits that made domesticated species different from their wild ancestors. He was also the first to recognize the difference between conscious selective breeding (i.e. artificial selection) in which humans directly select for desirable traits, and unconscious selection where traits evolve as a by-product of natural selection or from selection on other traits. There is a genetic difference between domestic and wild populations. There is also a genetic difference between the domestication traits that researchers believe to have been essential at the early stages of domestication, and the improvement traits that have appeared since the split between wild and domestic populations. Domestication traits are generally fixed within all domesticates, and were selected during the initial episode of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backing Sheep At Sheepdog Competition
The back is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck and the shoulders. Back may also refer to: People * Adam Back (born 1970), British cryptographer * Charles Back, South African winemaker * Chris Back (born 1950), Australian politician * Ernst Emil Alexander Back (1881–1959), German physicist * Frédéric Back (born 1924), Canadian animator * George Back (1796–1878), British naval officer and explorer * Les Back (born 1962), English sociology professor and author * Natasja Crone Back (born 1971), Danish journalist * Neil Back (born 1969), English rugby player * Ralph-Johan Back, Finnish computer scientist * Rico Back (born 1954), Swiss-domiciled German businessman * Sven-Erik Bäck (1919–1984), Swedish composer * William Back (1856–1911), Australian cricketer Places * Back (crater), lunar crater * Back, Lewis, a village on the Isle of Lewis, Scotland * Back Bay (other), several places * Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goat
The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the animal family Bovidae and the tribe Caprini, meaning it is closely related to the sheep. There are over 300 distinct breeds of goat.Hirst, K. Kris"The History of the Domestication of Goats".''About.com''. Accessed August 18, 2008. It is one of the oldest domesticated species of animal, according to archaeological evidence that its earliest domestication occurred in Iran at 10,000 calibrated calendar years ago. Goats have been used for milk, meat, fur, and skins across much of the world. Milk from goats is often turned into goat cheese. Female goats are referred to as ''does'' or ''nannies'', intact males are called ''bucks'' or ''billies'', and juvenile goats of both sexes are called ''kids''. Castrated males are called ''wethers''. Whil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution Of Temperature In The Post-Glacial Period According To Greenland Ice Cores (Younger Dryas)
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation tends to exist within any given population as a result of genetic mutation and recombination. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or more rare within a population. The evolutionary pressures that determine whether a characteristic is common or rare within a population constantly change, resulting in a change in heritable characteristics arising over successive generations. It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules. The theory of evolution by na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological properties, its behavior, and the products of behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code, or its genotype, and the influence of environmental factors. Both factors may interact, further affecting phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and then again in his 1982 book ''The Extended Phenotype'' suggested that one can regard bird nests and other built structures such as cad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Domestication Syndrome
Domestication syndrome refers to two sets of phenotypic traits that are common to either domesticated animals, or domesticated plants. These traits were identified by Charles Darwin in '' The Variation of Animals and Plants Under Domestication.'' Domesticated animals tend to be smaller and less aggressive than their wild counterparts, they may also have floppy ears, variations to coat color, a smaller brain, and a shorter muzzle. Other traits may include changes in the endocrine system and an extended breeding cycle. Research suggests that modified neural crest cells are potentially responsible for the traits that are common across many domesticated animal species. The process of plant domestication has produced changes in shattering/fruit abscission, shorter height, larger grain or fruit size, easier threshing, synchronous flowering, and increased yield, as well as changes in color, taste, and texture. Origin Charles Darwin's study of ''The Variation of Animals and Plan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traits Defining Domestication Syndrome , a type of role-playing statistic
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Trait may refer to: * Phenotypic trait in biology, which involve genes and characteristics of organisms * Genotypic trait, sometimes but not always presenting as a phenotypic trait * Trait (computer programming), a model for structuring object-oriented programs (a template class in the C++ programming language) * Personality, traits that predict an individual's behavior. ** Trait theory in psychology Entertainment * ''Trait'' (album), the first and only EP by the industrial rock/metal band Pailhead * ''Traits'' (Joe Morris album) * Trait (role-playing games) A statistic (or stat) in role-playing games is a piece of data that represents a particular aspect of a fictional character. That piece of data is usually a (unitless) integer or, in some cases, a set of dice. For some types of statistics, thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leafcutter Ants
Leafcutter ants, a non-generic name, are any of 47 species of leaf-chewing ants belonging to the two genera ''Atta'' and ''Acromyrmex''. These species of tropical, fungus-growing ants are all endemic to South and Central America, Mexico, and parts of the southern United States.. Leafcutter ants can carry twenty times their body weight and cut and process fresh vegetation (leaves, flowers, and grasses) to serve as the nutritional substrate for their fungal cultivates. ''Acromyrmex'' and ''Atta'' ants have much in common anatomically; however, the two can be identified by their external differences. ''Atta'' ants have three pairs of spines and a smooth exoskeleton on the upper surface of the thorax, while ''Acromyrmex'' ants have four pairs and a rough exoskeleton. The exoskeleton itself is covered in a thin layer of mineral coating, composed of rhombohedral crystals that are generated by the ants. Next to humans, leafcutter ants form some of the largest and most complex animal s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ant–fungus Mutualism
The ant–fungus mutualism is a symbiosis seen between certain ant and fungal species, in which ants actively cultivate fungus much like humans farm crops as a food source. There is only evidence of two instances in which this form of agriculture evolved in ants resulting in a dependence on fungi for food. These instances were the attine ants and some ants that are part of the ''Megalomyrmex'' genus. In some species, the ants and fungi are dependent on each other for survival. This type of codependency is prevalent among herbivores who rely on plant material for nutrition. The microbes’ ability to convert the plant material into a food source accessible to their host makes them the ideal partner. The leafcutter ant is a well-known example of this symbiosis. Leafcutter ants species can be found in southern South America up to the United States. However, ants are not the only ground-dwelling arthropods which have developed symbioses with fungi. A mutualism with fungi is also noted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fitness (biology)
Fitness (often denoted w or ω in population genetics models) is the quantitative representation of individual reproductive success. It is also equal to the average contribution to the gene pool of the next generation, made by the same individuals of the specified genotype or phenotype. Fitness can be defined either with respect to a genotype or to a phenotype in a given environment or time. The fitness of a genotype is manifested through its phenotype, which is also affected by the developmental environment. The fitness of a given phenotype can also be different in different selective environments. With asexual reproduction, it is sufficient to assign fitnesses to genotypes. With sexual reproduction, recombination scrambles alleles into different genotypes every generation; in this case, fitness values can be assigned to alleles by averaging over possible genetic backgrounds. Natural selection tends to make alleles with higher fitness more common over time, resulting in Darwin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symbiosis
Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasitic. The organisms, each termed a symbiont, must be of different species. In 1879, Heinrich Anton de Bary defined it as "the living together of unlike organisms". The term was subject to a century-long debate about whether it should specifically denote mutualism, as in lichens. Biologists have now abandoned that restriction. Symbiosis can be obligatory, which means that one or more of the symbionts depend on each other for survival, or facultative (optional), when they can generally live independently. Symbiosis is also classified by physical attachment. When symbionts form a single body it is called conjunctive symbiosis, while all other arrangements are called disjunctive symbiosis."symbiosis." Dorland's Illustrated Medical Dictionary. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reproduction
Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction. There are two forms of reproduction: asexual and sexual. In asexual reproduction, an organism can reproduce without the involvement of another organism. Asexual reproduction is not limited to single-celled organisms. The cloning of an organism is a form of asexual reproduction. By asexual reproduction, an organism creates a genetically similar or identical copy of itself. The evolution of sexual reproduction is a major puzzle for biologists. The two-fold cost of sexual reproduction is that only 50% of organisms reproduce and organisms only pass on 50% of their genes.John Maynard Smith ''The Evolution of Sex'' 1978. Sexual reproduction typically requires the sexual interaction of two specializ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organism
In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea. All types of organisms are capable of reproduction, growth and development, maintenance, and some degree of response to stimuli. Beetles, squids, tetrapods, mushrooms, and vascular plants are examples of multicellular organisms that differentiate specialized tissues and organs during development. A unicellular organism may be either a prokaryote or a eukaryote. Prokaryotes are represented by two separate domains – bacteria and archaea. Eukaryotic organisms are characterized by the presence of a membrane-bound cell nucleus and contain additional membrane-bound compartments called organelles (such as mitochondria in animals and plants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
