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Sperm Competition
Sperm competition is the competitive process between spermatozoa of two or more different males to fertilize the same egg during sexual reproduction. Competition can occur when females have multiple potential mating partners. Greater choice and variety of mates increases a female's chance to produce more viable offspring. However, multiple mates for a female means each individual male has decreased chances of producing offspring. Sperm competition is an evolutionary pressure on males, and has led to the development of adaptations to increase males' chance of reproductive success. Sperm competition results in a sexual conflict of interest between males and females. Males have evolved several defensive tactics including: mate-guarding, mating plugs, and releasing toxic seminal substances to reduce female re-mating tendencies to cope with sperm competition. Offensive tactics of sperm competition involve direct interference by one male on the reproductive success of another male, f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sperm Stained
Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, which are known as spermatozoa, while some red algae and fungi produce non-motile sperm cells, known as spermatia. Flowering plants contain non-motile sperm inside pollen, while some more basal plants like ferns and some gymnosperms have motile sperm. Sperm cells form during the process known as spermatogenesis, which in amniotes ( reptiles and mammals) takes place in the seminiferous tubules of the testes. This process involves the production of several successive sperm cell precursors, starting with spermatogonia, which differentiate into spermatocytes. The spermatocytes then undergo meiosis, reducing their chromosome number by half, which produces spermatids. The spermatids then mature and, in animals, construct a tail, or flagellum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mate Guarding In Humans
Human mate guarding refers to behaviours employed by both males and females with the aim of maintaining reproductive opportunities and sexual access to a mate. It involves discouraging the current mate from abandoning the relationship whilst also warding off intrasexual (same sex) rivals. It has been observed in many non-human animals (see sperm competition), as well as humans. Sexual jealousy is a prime example of mate guarding behaviour. Both males and females use different strategies to retain a mate and there is evidence that suggests resistance to mate guarding also exists.Buss, D. M. (2002). Human mate guarding. N''euroendocrinology Letters, 23'' (4), 23-29. Male Circumstances of use Mate guarding behaviour in males is much more likely to be elicited by the threat of sexual infidelity in a female partner, in comparison to emotional involvement outside the mateship. This is primarily due to the risk female infidelity poses for male paternity, or 'genetic cuckoldry'. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poecilia
''Poecilia'' is a genus of fishes in the family Poeciliidae of the order Cyprinodontiformes. These livebearers are native to fresh, brackish and salt water in the Americas, and some species in the genus are euryhaline. A few have adapted to living in waters that contain high levels of toxic hydrogen sulfide ()Palacios, Arias-Rodriguez, Plath, Eifert, Lerp, Lamboj, Voelker, & Tobler (2013). The Rediscovery of a Long Described Species Reveals Additional Complexity in Speciation Patterns of Poeciliid Fishes in Sulfide Springs.' PLoS ONE 8(8): e71069. and a population of '' P. mexicana'' lives in caves (other populations of this species are surface-living). Some common and widespread species are often kept as aquarium fish, while other have very small ranges and are seriously threatened. All species in ''Poecilia'' are called mollies except for the Endler's livebearer (''P. wingei'') and the well-known guppy (''P. reticulata'') which have a distinctly different body shape fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalassoma Bifasciatum
''Thalassoma bifasciatum'', the bluehead, bluehead wrasse or blue-headed wrasse, is a species of marine ray-finned fish, a wrasse from the family Labridae. It is native to the coral reefs of the tropical waters of the western Atlantic Ocean. Individuals are small (less than 110 mm standard length) and rarely live longer than two years. They form large schools over the reef and are important cleaner fish in the reefs they inhabit. Distribution and habitat ''Thalassoma bifasciatum'' is found in coral reefs of the Atlantic Ocean. Its main range includes the Caribbean Sea and the southeast area of the Gulf of Mexico. Description Young/small females and males have yellow upper bodies and white lower bodies, often with green or black lateral stripes and occasionally dark vertical bars. This coloration is known as the initial phase. They can rapidly alter the presence or intensity of their yellow color, stripes, and bars, and these color changes appear to correspond to beha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accessory Gland
This glossary of entomology describes terms used in the formal study of insect species by entomologists. A–C A synthetic chlorinated hydrocarbon insecticide, toxic to vertebrates. Though its phytotoxicity is low, solvents in some formulations may damage certain crops. cf. the related Dieldrin, Endrin, Isodrin * D–F A synthetic chlorinated hydrocarbon insecticide, toxic to vertebrates. cf. the related Aldrin, Endrin, Isodrin A synthetic chlorinated hydrocarbon insecticide, toxic to vertebrates. Though its phytotoxicity is low, solvents in some formulations may damage certain crops. cf. the related Dieldrin, Aldrin, Isodrin G–L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Melanogaster
''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the " vinegar fly" or " pomace fly". Starting with Charles W. Woodworth's 1901 proposal of the use of this species as a model organism, ''D. melanogaster'' continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and life history evolution. As of 2017, five Nobel Prizes have been awarded to drosophilists for their work using the insect. ''D. melanogaster'' is typically used in research owing to its rapid life cycle, relatively simple genetics with only four pairs of chromosomes, and large number of offspring per generation. It was originally an African species, with all non-African lineages having a common origin. Its geographic range includes all continents, including islands. ''D. melanogaster'' is a common pest in homes, restaurants, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Mettleri
''Drosophila metlerri'', commonly known as the Sonoran Desert fly, is a fly in the genus '' Drosophila''. The species is found in North America and is most concentrated along the southern coast of California and in Mexico. ''D. mettleri'' are dependent on plant hosts, namely, the saguaro and cardon cacti. Thus, they are most prevalent in arid, desert conditions. It is able to detoxify chemicals found in the rotting liquid of cacti hosts, which allows it to use otherwise lethal soil as a nesting site. ''D. mettleri'' was discovered in San Felipe, Baja California in October 1961 during an experiment where banana was used to attract several species of ''Drosophila''. Due to physical geographic barriers between Sonoran Desert flies, gene flow explains speciation. It breeds in soil moistened by liquid excreted by rotting cacti and on necrotic patches. The liquid found in rotting cacti patches serves as a nutrient source for ''D. mettleri'' larvae, despite it containing chemicals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linoleic Acid
Linoleic acid (LA) is an organic compound with the formula COOH(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups are ''cis''. It is a fatty acid sometimes denoted 18:2 (n-6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid. Linoleic acid is a polyunsaturated omega-6 fatty acid. It is a colorless liquid that is virtually insoluble in water but soluble in many organic solvents. It typically occurs in nature as a triglyceride (ester of glycerin) rather than as a free fatty acid. It is one of two essential fatty acids for humans, who must obtain it through their diet, and the most essential, because the body uses it as a base to make the others. The word "linoleic" derives from the Latin ''linum'' "flax" + ''oleum'' "oil", reflecting the fact that it was first isolated from linseed oil. History In 1844, F. Sacc, working at the laboratory of Justus von Liebig, isolated linoleic acid from linseed oil. In 1886, K. Peters determined the existence of two double ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bumblebee
A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related genera (e.g., '' Calyptapis'') are known from fossils. They are found primarily in higher altitudes or latitudes in the Northern Hemisphere, although they are also found in South America, where a few lowland tropical species have been identified. European bumblebees have also been introduced to New Zealand and Tasmania. Female bumblebees can sting repeatedly, but generally ignore humans and other animals. Most bumblebees are social insects that form colonies with a single queen. The colonies are smaller than those of honey bees, growing to as few as 50 individuals in a nest. Cuckoo bumblebees are brood parasitic and do not make nests or form colonies; their queens aggressively invade the nests of other bumblebee species, kill the resident q ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copulatory Plug
A mating plug, also known as a copulation plug, sperm plug, vaginal plug, or sphragis (Latin, from Greek σφραγίς ''sphragis'', "a seal"), is gelatinous secretion used in the mating of some species. It is deposited by a male into a female genital tract, such as the vagina, and later hardens into a plug or glues the tract together. While females can expel the plugs afterwards, the male's sperm still gets a time advantage in getting to the egg, which is often the deciding factor in fertilization. The mating plug plays an important role in sperm competition and may serve as an alternative and more advantageous strategy to active mate guarding. In some species, such a passive mate-guarding strategy may reduce selection on large male size. Such a strategy may be advantageous because it would allow a male to increase reproductive success by spending more time pursuing new female mates rather than active mate guarding. Composition The mating plug of the ''Bombus terrestris'' was c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Melanogaster - Side (aka)
''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the Tephritidae, a related family, which are also called fruit flies (sometimes referred to as "true fruit flies"); tephritids feed primarily on unripe or ripe fruit, with many species being regarded as destructive agricultural pests, especially the Mediterranean fruit fly. One species of ''Drosophila'' in particular, ''D. melanogaster'', has been heavily used in research in genetics and is a common model organism in developmental biology. The terms "fruit fly" and "''Drosophila''" are often used synonymously with ''D. melanogaster'' in modern biological literature. The entire genus, however, contains more than 1,500 species and is very diverse in appearance, beha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indianmeal Moth 2009
Cornmeal is a meal (coarse flour) or a cell membrane ground from dried corn. It is a common staple food, and is ground to coarse, medium, and fine consistencies, but not as fine as wheat flour can be.Herbst, Sharon, ''Food Lover's Companion'', Third Edition, Pg. 165, Barrons Educational Series Inc, 2001 In Mexico, very finely ground cornmeal is referred to as corn flour. When fine cornmeal is made from maize that has been soaked in an alkaline solution, e.g., limewater (a process known as nixtamalization), it is called masa harina (or masa flour), which is used for making arepas, tamales and tortillas. Boiled cornmeal is called polenta in Italy and is also a traditional dish and bread substitute in Romania. Types There are various types of cornmeal: *''Blue cornmeal'' is light blue or violet in color. It is ground from whole blue corn and has a sweet flavor. The cornmeal consists of dried corn kernels that have been ground into a fine or medium texture. *''Steel-ground yellow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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