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Marginal Value Theorem
The marginal value theorem (MVT) is an optimality model that usually describes the behavior of an optimally foraging individual in a system where resources (often food) are located in discrete patches separated by areas with no resources. Due to the resource-free space, animals must spend time traveling between patches. The MVT can also be applied to other situations in which organisms face diminishing returns. The MVT was first proposed by Eric Charnov in 1976. In his original formulation: "The predator should leave the patch it is presently in when the marginal capture rate in the patch drops to the average capture rate for the habitat." Charnov, E. L. 1976. Optimal foraging: the marginal value theorem. Theoretical Population Biology 9:129–136 Definition All animals must forage for food in order to meet their energetic needs, but doing so is energetically costly. It is assumed that evolution by natural selection results in animals utilizing the most economic and efficient strat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optimality Model
In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ..., optimality models are a tool used to evaluate the costs and benefits of different organismal features, traits, and characteristics, including behavior, in the natural world. This evaluation allows researchers to make predictions about an organisms's optimal behavior or other aspects of its phenotype. Optimality modeling is the modeling aspect of optimization theory. It allows for the calculation and visualization of the costs and benefits that influence the outcome of a decision, and contributes to an understanding of adaptations. The approach based on optimality models in biology is sometimes called optimality theory. Optimal behavior is defined as an action that maximizes the difference between the costs and benefits of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diminishing Returns
In economics, diminishing returns are the decrease in marginal (incremental) output of a production process as the amount of a single factor of production is incrementally increased, holding all other factors of production equal ( ceteris paribus). The law of diminishing returns (also known as the law of diminishing marginal productivity) states that in productive processes, increasing a factor of production by one unit, while holding all other production factors constant, will at some point return a lower unit of output per incremental unit of input. The law of diminishing returns does not cause a decrease in overall production capabilities, rather it defines a point on a production curve whereby producing an additional unit of output will result in a loss and is known as negative returns. Under diminishing returns, output remains positive, however productivity and efficiency decrease. The modern understanding of the law adds the dimension of holding other outputs equal, since ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eric Charnov
Eric Lee Charnov (born October 29, 1947) is an American evolutionary ecologist. He is best known for his work on foraging, especially the marginal value theorem, and life history theory, especially sex allocation and scaling/allometric rules. He is a MacArthur Fellow and a Fellow of the American Academy of Arts and Sciences. Two of his papers are Science Citation Classics. Charnov gained his B.S. in 1969 from the University of Michigan and his PhD in evolutionary ecology from the University of Washington in 1973. He is a Distinguished Professor (Emeritus) of Biology at the University of New Mexico and the University of Utah. His research interests are: metabolic ecology (temperature and body size in the determination of biological times and rates) and evolutionary ecology: population genetics, evolutionary game theory, and optimization models to understand the evolution of life histories, sex allocation, sexual selection, and foraging Foraging is searching for wild food ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Tit
The great tit (''Parus major'') is a passerine bird in the tit family Paridae. It is a widespread and common species throughout Europe, the Middle East, Central Asia and east across the Palearctic to the Amur River, south to parts of North Africa where it is generally resident in any sort of woodland; most great tits do not migrate except in extremely harsh winters. Until 2005 this species was lumped with numerous other subspecies. DNA studies have shown these other subspecies to be distinct from the great tit and these have now been separated as two distinct species, the cinereous tit (''Parus cinereus'') of southern Asia, and the Japanese tit (''Parus minor'') of East Asia. The great tit remains the most widespread species in the genus ''Parus''. The great tit is a distinctive bird with a black head and neck, prominent white cheeks, olive upperparts and yellow underparts, with some variation amongst the numerous subspecies. It is predominantly insectivorous in the summer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optimal Foraging Theory
Optimal foraging theory (OFT) is a behavioral ecology model that helps predict how an animal behaves when searching for food. Although obtaining food provides the animal with energy, searching for and capturing the food require both energy and time. To maximize fitness, an animal adopts a foraging strategy that provides the most benefit (energy) for the lowest cost, maximizing the net energy gained. OFT helps predict the best strategy that an animal can use to achieve this goal. OFT is an ecological application of the optimality model. This theory assumes that the most economically advantageous foraging pattern will be selected for in a species through natural selection. When using OFT to model foraging behavior, organisms are said to be maximizing a variable known as the currency, such as the most food per unit time. In addition, the constraints of the environment are other variables that must be considered. Constraints are defined as factors that can limit the forager's abili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Screaming Hairy Armadillo
The screaming hairy armadillo (''Chaetophractus vellerosus'') is a species of armadillo also known as the small screaming armadillo, crying armadillo or the small hairy armadillo. It is a burrowing armadillo found in the central and southern parts of South America. The adjective "screaming" derives from its habit of squealing when handled. Taxonomy The animal was first described by J. E. Gray in 1865 from a specimen in the British Museum collected from Santa Cruz de la Sierra in eastern Bolivia as ''Dasypus vellerosus''. Two subspecies are currently recognized (''C. v. vellerosus'' (Gray, 1865) and ''C. v. pannosus'' (Gardner, 2007)) although the taxonomic validity of the split has been called into question. Description This is one of the smallest and slenderest species of the genus ''Chaetophractus'', but it has longer ears than others in its genus. The male armadillo has a length ranging from with an average length of , while the length of the female ranges from with an ave ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guinea Pig
The guinea pig or domestic guinea pig (''Cavia porcellus''), also known as the cavy or domestic cavy (), is a species of rodent belonging to the genus ''Cavia'' in the family Caviidae. Breeders tend to use the word ''cavy'' to describe the animal, while in scientific and laboratory contexts, it is far more commonly referred to by the common name ''guinea pig''. Despite their common name, guinea pigs are not native to Guinea, nor are they closely related biologically to pigs, and the origin of the name is still unclear. They originated in the Andes of South America. Studies based on biochemistry and hybridization suggest they are domesticated animals that do not exist naturally in the wild, descendants of a closely related cavy species such as '' C. tschudii''. They were originally domesticated as livestock for a source of meat, and are still consumed in some parts of the world. In Western society, the guinea pig has enjoyed widespread popularity as a pet since its introducti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scathophaga Stercoraria
''Scathophaga stercoraria'', commonly known as the yellow dung fly or the golden dung fly, is one of the most familiar and abundant flies in many parts of the Northern Hemisphere. As its common name suggests, it is often found on the feces of large mammals, such as horses, cattle, sheep, deer, and wild boar, where it goes to breed. The distribution of ''S. stercoraria'' is likely influenced by human agriculture, especially in northern Europe and North America. The ''Scathophaga'' are integral in the animal kingdom due to their role in the natural decomposition of dung in fields. They are also very important in the scientific world due to their short life cycles and susceptibility to experimental manipulations; thus, they have contributed significant knowledge about animal behavior. Description ''Scathophaga stercoraria'' is sexually dimorphic, with an average lifespan of one to two months. The adult males are bright golden-yellow with orange-yellow fur on the front legs. Females ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diminishing Returns
In economics, diminishing returns are the decrease in marginal (incremental) output of a production process as the amount of a single factor of production is incrementally increased, holding all other factors of production equal ( ceteris paribus). The law of diminishing returns (also known as the law of diminishing marginal productivity) states that in productive processes, increasing a factor of production by one unit, while holding all other production factors constant, will at some point return a lower unit of output per incremental unit of input. The law of diminishing returns does not cause a decrease in overall production capabilities, rather it defines a point on a production curve whereby producing an additional unit of output will result in a loss and is known as negative returns. Under diminishing returns, output remains positive, however productivity and efficiency decrease. The modern understanding of the law adds the dimension of holding other outputs equal, since ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Behavioral Ecology
Behavioral ecology, also spelled behavioural ecology, is the study of the evolutionary basis for animal behavior due to ecological pressures. Behavioral ecology emerged from ethology after Niko Tinbergen outlined four questions to address when studying animal behaviors: What are the proximate causes, ontogeny, survival value, and phylogeny of a behavior? If an organism has a trait that provides a selective advantage (i.e., has adaptive significance) in its environment, then natural selection favors it. Adaptive significance refers to the expression of a trait that affects fitness, measured by an individual's reproductive success. Adaptive traits are those that produce more copies of the individual's genes in future generations. Maladaptive traits are those that leave fewer. For example, if a bird that can call more loudly attracts more mates, then a loud call is an adaptive trait for that species because a louder bird mates more frequently than less loud birds—thus sending mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
