Drosophila melanogaster
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drozofila
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- Scientific classification
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- Synonyms Oinopota Kirby Spence, 1815 Drosophila
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This article is about the entire genus. For the most commonly used laboratory species, often just called Drosophila, see Drosophila melanogaster. For the type-subgenus, see Drosophila (subgenus). For a mushroom that once shared this name, see Psathyrella candolleana.
Drosophila (/drəˈsɒfɪlə, drɒ-, droʊ-/[1][2]) is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently)[citation needed] 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[3] and is very diverse in appearance, behavior, and breeding habitat. Etymology[edit] The term "Drosophila", meaning "dew-loving", is a modern scientific Latin adaptation from Greek words δρόσος, drósos, "dew", and φιλία, philía, "lover". Morphology[edit] Drosophila species are small flies, typically pale yellow to reddish brown to black, with red eyes. When the eyes (essentially a film of lenses) are removed, the brain is revealed. Drosophila brain structure and function develop and age significantly from larval to adult stage. Developing brain structures make these flies a prime candidate for neuro-genetic research.[4] Many species, including the noted Hawaiian picture-wings, have distinct black patterns on the wings. The plumose (feathery) arista, bristling of the head and thorax, and wing venation are characters used to diagnose the family. Most are small, about 2–4 millimetres (0.079–0.157 in) long, but some, especially many of the Hawaiian species, are larger than a house fly. Evolution[edit]
Detoxification mechanisms[edit] Environmental challenge by natural toxins helped to prepare Drosophilae to detox DDT,[5]: Abstract [5]: 1365 [5]: 1369 by shaping the glutathione S-transferase mechanism[5]: 1365 [5]: 1369 that metabolizes both.[5]: Abstract [6] Selection[edit] The Drosophila genome is subject to a high degree of selection, especially unusually widespread negative selection compared to other taxa. A majority of the genome is under selection of some sort, and a supermajority of this is occurring in non-coding DNA.[7] Effective population size has been credibly suggested to positively correlate with the effect size of both negative and positive selection. Recombination is likely to be a significant source of diversity. There is evidence that crossover is positively correlated with polymorphism in D. populations.[7] Biology[edit] Habitat[edit] Drosophila species are found all around the world, with more species in the tropical regions. Drosophila made their way to the Hawaiian Islands and radiated into over 800 species.[8] They can be found in deserts, tropical rainforest, cities, swamps, and alpine zones. Some northern species hibernate. The northern species D. montana is the best cold-adapted,[9] and is primarily found at high altitudes.[10] Most species breed in various kinds of decaying plant and fungal material, including fruit, bark, slime fluxes, flowers, and mushrooms. Drosophila species that are fruit-breeding are attracted to various products of fermentation, especially ethanol and methanol. Fruits exploited by Drosophila species include those with a high pectin concentration, which is an indicator of how much alcohol will be produced during fermentation. Citrus, morinda, apples, pears, plums, and apricots belong into this category.[11] The larvae of at least one species, D. suzukii, can also feed in fresh fruit and can sometimes be a pest.[12] A few species have switched to being parasites or predators. Many species can be attracted to baits of fermented bananas or mushrooms, but others are not attracted to any kind of baits. Males may congregate at patches of suitable breeding substrate to compete for the females, or form leks, conducting courtship in an area separate from breeding sites.[citation needed] Several Drosophila species, including Drosophila melanogaster, D. immigrans, and D. simulans, are closely associated with humans, and are often referred to as domestic species. These and other species (D. subobscura, and from a related genus Zaprionus indianus[13][14][15]) have been accidentally introduced around the world by human activities such as fruit transports. Side view of head showing characteristic bristles above the eye Reproduction[edit] Males of this genus are known to have the longest sperm cells of any studied organism on Earth, including one species, Drosophila bifurca, that has sperm cells that are 58 mm (2.3 in) long.[16] The cells mostly consist of a long, thread-like tail, and are delivered to the females in tangled coils. The other members of the genus Drosophila also make relatively few giant sperm cells, with that of D. bifurca being the longest.[17] D. melanogaster sperm cells are a more modest 1.8 mm long, although this is still about 35 times longer than a human sperm. Several species in the D. melanogaster species group are known to mate by traumatic insemination.[18] Drosophila species vary widely in their reproductive capacity. Those such as D. melanogaster that breed in large, relatively rare resources have ovaries that mature 10–20 eggs at a time, so that they can be laid together on one site. Others that breed in more-abundant but less nutritious substrates, such as leaves, may only lay one egg per day. The eggs have one or more respiratory filaments near the anterior end; the tips of these extend above the surface and allow oxygen to reach the embryo. Larvae feed not on the vegetable matter itself, but on the yeasts and microorganisms present on the decaying breeding substrate. Development time varies widely between species (between 7 and more than 60 days) and depends on the environmental factors such as temperature, breeding substrate, and crowding. Fruit flies lay eggs in response to environmental cycles. Eggs laid at a time (e.g., night) during which likelihood of survival is greater than in eggs laid at other times (e.g., day) yield more larvae than eggs that were laid at those times. Ceteris paribus, the habit of laying eggs at this 'advantageous' time would yield more surviving offspring, and more grandchildren, than the habit of laying eggs during other times. This differential reproductive success would cause D. melanogaster to adapt to environmental cycles, because this behavior has a major reproductive advantage.[19] Their median lifespan is 35–45 days.[20] Download 148.21 Kb. Do'stlaringiz bilan baham: 
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