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Cost Of Reproduction Hypothesis
In life history theory, the cost of reproduction hypothesis is the idea that reproduction is costly in terms of future survival and reproduction. This is mediated by various mechanisms, with the two most prominent being hormonal regulation and differential allocation of internal resources. Definition and predictions The cost of reproduction hypothesis posits that reproduction (and increased reproductive effort) is costly in terms of future survival and reproduction. These costs may be exacerbated in certain organisms, such as first--time breeders. Along with the idea that organisms are selected to maximize lifetime reproductive success, this hypothesis results in a trade-off between current reproduction and future fitness that is pivotal in life history theory. This trade-off can be analyzed on three levels: the genetic (which analyzes the genetic basis of covariation between traits), the phenotypic (which assess how traits directly connected to fitness covary), and the intermediate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life History Theory
Life history theory (LHT) is an analytical frameworkVitzthum, V. (2008). Evolutionary models of women's reproductive functioning. ''Annual Review of Anthropology'', ''37'', 53-73 designed to study the diversity of life history strategies used by different organisms throughout the world, as well as the causes and results of the variation in their life cycles.Flatt, T., & Heyland, A. (Eds.). (2011). Mechanisms of Life History Evolution : The Genetics and Physiology of Life History Traits and Trade-Offs. Oxford, GB: OUP Oxford. It is a theory of biological evolution that seeks to explain aspects of organisms' anatomy and behavior by reference to the way that their life histories—including their reproductive development and behaviors, post-reproductive behaviors, and lifespan (length of time alive)—have been shaped by natural selection. A life history strategy is the "age- and stage-specific patterns" and timing of events that make up an organism's life, such as birth, weaning, matu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 appear in the genetic code of life. Amino acids can be classified according to the locations of the core structural functional groups ( alpha- , beta- , gamma- amino acids, etc.); other categories relate to polarity, ionization, and side-chain group type ( aliphatic, acyclic, aromatic, polar, etc.). In the form of proteins, amino-acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life on Earth and its emergence. Amino acids are formally named by the IUPAC- IUBMB Joint Commi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terminal Investment Hypothesis
The terminal investment hypothesis is the idea in life history theory that as an organism's residual reproductive value (or the total reproductive value minus the reproductive value of the current breeding attempt) decreases, its reproductive effort will increase. Thus, as an organism's prospects for survival decreases (through age or an immune challenge, for example), it will invest more in reproduction. This hypothesis is generally supported in animals, although results contrary to it do exist. Definition The terminal investment hypothesis posits that as residual reproductive value (measured as the total reproductive value minus the reproductive value of the current breeding attempt) decreases, reproductive effort increases. This is based on the cost of reproduction hypothesis, which says that an increase in resources dedicated to current reproduction decreases the potential for future reproduction. But, as the residual reproductive value decreases, the importance of this trade-of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life History Theory
Life history theory (LHT) is an analytical frameworkVitzthum, V. (2008). Evolutionary models of women's reproductive functioning. ''Annual Review of Anthropology'', ''37'', 53-73 designed to study the diversity of life history strategies used by different organisms throughout the world, as well as the causes and results of the variation in their life cycles.Flatt, T., & Heyland, A. (Eds.). (2011). Mechanisms of Life History Evolution : The Genetics and Physiology of Life History Traits and Trade-Offs. Oxford, GB: OUP Oxford. It is a theory of biological evolution that seeks to explain aspects of organisms' anatomy and behavior by reference to the way that their life histories—including their reproductive development and behaviors, post-reproductive behaviors, and lifespan (length of time alive)—have been shaped by natural selection. A life history strategy is the "age- and stage-specific patterns" and timing of events that make up an organism's life, such as birth, weaning, matu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photuris
''Photuris'' is a genus of firefly, fireflies (beetles of the family (biology), family Lampyridae). These are the ''femme fatale'' lightning bugs of North America. This common name refers to a behavior of the adult females of these predatory beetles; they engage in aggressive mimicry, imitating the light signals of other firefly species' females to attract matesbut ''Photuris'' use it to attract, kill and eat the unsuspecting males of those other species. Their flashing bioluminescent signals seem to have evolved independently and eventually adaptation, adapted to those of their prey, mainly unrelated Lampyrinae, such as ''Photinus (beetle), Photinus'' (rover fireflies) or ''Pyractomena''. Species At least 64 species are currently recognized, all restricted to temperate North America. They mainly occur from the East Coast to Texas. Species include: *' – Barber, 1951 *''Photuris bethaniensis''– McDermott, 1953 *' – Barber, 1951 *' – Barber, 1951 *'– ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomy (biology), taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. Phylogeneti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fireflies
The Lampyridae are a family of elateroid beetles with more than 2,000 described species, many of which are light-emitting. They are soft-bodied beetles commonly called fireflies, lightning bugs, or glowworms for their conspicuous production of light, mainly during twilight, to attract mates. The type species is '' Lampyris noctiluca'', the common glow-worm of Europe. Light production in the Lampyridae is thought to have originated as a warning signal that the larvae were distasteful. This ability to create light was then co-opted as a mating signal and, in a further development, adult female fireflies of the genus ''Photuris'' mimic the flash pattern of the '' Photinus'' beetle to trap their males as prey. Fireflies are found in temperate and tropical climates. Many live in marshes or in wet, wooded areas where their larvae have abundant sources of food. Although all known fireflies glow as larvae, only some species produce light in their adult stage, and the location o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guppy
The Greater Underwater Propulsion Power Program (GUPPY) was initiated by the United States Navy after World War II to improve the submerged speed, maneuverability, and endurance of its submarines. (The "Y" in the acronym was added for pronounceability.) The navy began the program by testing and reverse engineering two German Type XXI U-boats— and —obtained as war reparation. That analysis led to four goals—increasing the submarines' battery capacity, streamlining the boats' structures, adding snorkels, and improving fire control systems. The navy immediately focused on designing a new class of submarine, but the Bureau of Ships believed the fleet of existing , , and submarines could be modified to incorporate the desired improvements. In June 1946, the Chief of Naval Operations approved the GUPPY project. The initial two-boat test program, implemented by the Portsmouth Naval Shipyard, eventually grew into several successive conversion programs. Those upgrades proceed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tenebrio Molitor
Mealworms are the larval form of the yellow mealworm beetle, ''Tenebrio molitor'', a species of darkling beetle. The yellow mealworm beetle prefers a warmer climate and higher humidity. Male mealworm beetles release a sex pheromone to attract females to mate. ''Tenebrio molitor'' has been used in biomedical research. Mealworms can be a dietary source for animals and humans. They are also considered pests, especially to food storage. Description Like all holometabolic insects, ''T. molitor'' goes through four life stages: egg, larva, pupa, and adult. Larvae typically measure about or more. Adults are generally in length. ''T. molitor'' is dark brown or black as an adult, with larvae up to long and adults up to long. The yellow mealworm beetle can be differentiated from other beetles, due to the linear grooves that are evenly divided and run along the abdomen. The beetle has only four tarsal segments on its hind legs. Most ground beetles, which are similar in size to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fatty Acid
In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an Branched chain fatty acids, unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are a major component of the lipids (up to 70% by weight) in some species such as microalgae but in some other organisms are not found in their standalone form, but instead exist as three main classes of esters: triglycerides, phospholipids, and cholesteryl esters. In any of these forms, fatty acids are both important diet (nutrition), dietary sources of fuel for animals and important structural components for cell (biology), cells. History The concept of fatty acid (''acide gras'') was introduced in 1813 by Michel Eugène Chevreul, though he initially used some variant terms: ''graisse acide'' and ''acide huileux'' ("acid fat" and "oi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terminal Investment Hypothesis
The terminal investment hypothesis is the idea in life history theory that as an organism's residual reproductive value (or the total reproductive value minus the reproductive value of the current breeding attempt) decreases, its reproductive effort will increase. Thus, as an organism's prospects for survival decreases (through age or an immune challenge, for example), it will invest more in reproduction. This hypothesis is generally supported in animals, although results contrary to it do exist. Definition The terminal investment hypothesis posits that as residual reproductive value (measured as the total reproductive value minus the reproductive value of the current breeding attempt) decreases, reproductive effort increases. This is based on the cost of reproduction hypothesis, which says that an increase in resources dedicated to current reproduction decreases the potential for future reproduction. But, as the residual reproductive value decreases, the importance of this trade-of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triglyceride
A triglyceride (from '' tri-'' and '' glyceride''; also TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids. Triglycerides are the main constituents of body fat in humans and other vertebrates as well as vegetable fat. They are also present in the blood to enable the bidirectional transference of adipose fat and blood glucose from the liver and are a major component of human skin oils. Many types of triglycerides exist. One specific classification focuses on saturated and unsaturated types. Saturated fats have ''no'' C=C groups; unsaturated fats feature one or more C=C groups. Unsaturated fats tend to have a lower melting point than saturated analogues; as a result, they are often liquid at room temperature. Chemical structure The three fatty acids substituents can be the same, but they are usually different. The positions of the three fatty acids are specified using stereospecific numbering as sn-1, sn-2, and sn- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
