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Drosophila

Drosophila

Overview
Drosophila is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of small flies
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...

, belonging to the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Drosophilidae
Drosophilidae
Drosophilidae is a diverse, cosmopolitan family of flies, which includes fruit flies. Another family of flies called Tephritidae also includes fruit flies. The best known species of Drosophilidae is Drosophila melanogaster, within the genus Drosophila, and this species Is used extensively for...

, whose members are often called "fruit flies" or more appropriately (though less frequently) pomace
Pomace
Pomace , or marc , is the solid remains of grapes, olives, or other fruit after pressing for juice or oil. It contains the skins, pulp, seeds, and stems of the fruit....

 flies, vinegar
Vinegar
Vinegar is a liquid substance consisting mainly of acetic acid and water, the acetic acid being produced through the fermentation of ethanol by acetic acid bacteria. Commercial vinegar is produced either by fast or slow fermentation processes. Slow methods generally are used with traditional...

 flies, or wine
Wine
Wine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...

 flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the Tephritidae
Tephritidae
Tephritidae is one of two fly families referred to as "fruit flies", the other family being Drosophilidae. Tephritidae does not include the biological model organisms of the genus Drosophila , which is often called the "common fruit fly". There are nearly 5,000 described species of tephritid...

, a related family, which are also called fruit flies (sometimes referred to as "true fruit flies"); tephritids feed primarily on unripe or ripe fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

, with many species being regarded as destructive agricultural pests, especially the Mediterranean fruit fly.
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Encyclopedia
Drosophila is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of small flies
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...

, belonging to the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Drosophilidae
Drosophilidae
Drosophilidae is a diverse, cosmopolitan family of flies, which includes fruit flies. Another family of flies called Tephritidae also includes fruit flies. The best known species of Drosophilidae is Drosophila melanogaster, within the genus Drosophila, and this species Is used extensively for...

, whose members are often called "fruit flies" or more appropriately (though less frequently) pomace
Pomace
Pomace , or marc , is the solid remains of grapes, olives, or other fruit after pressing for juice or oil. It contains the skins, pulp, seeds, and stems of the fruit....

 flies, vinegar
Vinegar
Vinegar is a liquid substance consisting mainly of acetic acid and water, the acetic acid being produced through the fermentation of ethanol by acetic acid bacteria. Commercial vinegar is produced either by fast or slow fermentation processes. Slow methods generally are used with traditional...

 flies, or wine
Wine
Wine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...

 flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the Tephritidae
Tephritidae
Tephritidae is one of two fly families referred to as "fruit flies", the other family being Drosophilidae. Tephritidae does not include the biological model organisms of the genus Drosophila , which is often called the "common fruit fly". There are nearly 5,000 described species of tephritid...

, a related family, which are also called fruit flies (sometimes referred to as "true fruit flies"); tephritids feed primarily on unripe or ripe fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

, with many species being regarded as destructive agricultural pests, especially the Mediterranean fruit fly. One species of Drosophila in particular, D. melanogaster
Drosophila melanogaster
Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...

, has been heavily used in research in genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

 and is a common model organism
Model organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. Model organisms are in vivo models and are widely used to...

 in developmental biology
Developmental biology
Developmental biology is the study of the process by which organisms grow and develop. Modern developmental biology studies the genetic control of cell growth, differentiation and "morphogenesis", which is the process that gives rise to tissues, organs and anatomy.- Related fields of study...

. Indeed, 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, behavior, and breeding habitat.

Etymology



The term "Drosophila", meaning "dew-loving", is a modern scientific Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 adaptation from Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 words , , "dew
Dew
[Image:Dew on a flower.jpg|right|220px|thumb|Some dew on an iris in Sequoia National Park]]Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening...

", and , , "loving" with the Latin feminine suffix -a.

Morphology



Drosophila are small flies, typically pale yellow to reddish brown to black, with red eyes. Many species, including the noted Hawaiian picture-wings, have distinct black patterns on the wings. The plumose (feathery) arista
Arista (biology)
In insect anatomy the arista is a simple or variously modified apical or subapical bristle, arising from the third antennal segment. It is the evolutionary remains of antennal segments, and may sometimes show signs of segmentation...

, bristling of the head and thorax, and wing venation are characters used to diagnose the family. Most are small, about 2–4 millimetres long, but some, especially many of the Hawaiian species, are larger than a house fly.

Habitat


Drosophila are found all around the world, with more species in the tropical regions. They can be found in deserts
Déserts
Déserts is a piece by Edgard Varèse for brass , percussion , piano, and tape. Percussion instruments are exploited for their resonant potential, rather than used solely as accompaniment...

, tropical rainforest
Tropical rainforest
A tropical rainforest is an ecosystem type that occurs roughly within the latitudes 28 degrees north or south of the equator . This ecosystem experiences high average temperatures and a significant amount of rainfall...

, cities, swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...

s, and alpine zones
Alpine climate
Alpine climate is the average weather for a region above the tree line. This climate is also referred to as mountain climate or highland climate....

. Some northern species hibernate
Hibernation
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...

. Most species breed in various kinds of decaying plant and fungal
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

 material, including fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

, bark
Bark
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...

, slime flux
Slime flux
Slime flux is a bacterial disease of certain trees, primarily elm, cottonwood, poplar, boxelder, ash, aspen, fruitless mulberry,pun-jins and oak. A wound to the bark, caused by pruning, insects, poor branch angles or natural cracks and splits, causes sap to ooze from the wound...

es, flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s, and mushroom
Mushroom
A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...

s. The larvae of at least one species, D. suzukii
Drosophila suzukii
Drosophila suzukii, commonly called the spotted-wing drosophila, is a vinegar fly—closely related to Drosophila melanogaster . Native to southeast Asia, D. suzukii was first described in 1931 by Matsumura. Observed in Japan as early as 1916 by T. Kanzawa, D...

, can also feed in fresh fruit and can sometimes be a pest. A few species have switched to being parasites
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

 or predators. Many species can be attracted to baits of fermented banana
Banana
Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....

s 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
Lek (animal behaviour)
A lek is a gathering of males, of certain animal species, for the purposes of competitive mating display. Leks assemble before and during the breeding season, on a daily basis. The same group of males meet at a traditional place and take up the same individual positions on an arena, each occupying...

, conducting courtship in an area separate from breeding sites.

Several Drosophila species, including D. melanogaster, D. immigrans, and D. simulans
Drosophila simulans
Drosophila simulans is a species of fly closely related to D. melanogaster and which belongs to the same melanogaster species subgroup. Its closest relatives are D. mauritiana and D. sechellia...

, are closely associated with humans, and are often referred to as domestic
Domestication
Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been...

 species. These and other species (D. subobscura, Zaprionus indianus) have been accidentally introduced around the world by human activities such as fruit transports.

Reproduction


Males of this genus are known to have the longest sperm cells
Spermatozoon
A spermatozoon is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote...

 of any organism on Earth, including one species, Drosophila bifurca
Drosophila bifurca
Drosophila bifurca is a species of fruit fly. Males of this species are known to have the longest sperm cells of any organism on Earth, an astonishing 5.8 cm long when uncoiled. The cells are mostly tail, and are delivered to the females in tangled coils. In a male's entire life he can only...

, that has sperm 58 mm (2.3 in) long. The cells are mostly 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. D. melanogaster sperm cells are a more modest 1.8 mm long, although this is still about 300 times longer than a human sperm. Several species in the D. melanogaster species group are known to mate by traumatic insemination
Traumatic insemination
Traumatic insemination, also known as hypodermic insemination, is the mating practice in some species of invertebrates in which the male pierces the female's abdomen with his penis and injects his sperm through the wound into her abdominal cavity . The sperm diffuse through the female's hemolymph,...

.

Drosophila 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 yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...

s and microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

s 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
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

, breeding substrate, and crowding.

Laboratory–cultured animals


Drosophila melanogaster is a popular experimental animal because it is easily cultured in mass out of the wild, has a short generation time, and mutant animals are readily obtainable. In 1906, Thomas Hunt Morgan
Thomas Hunt Morgan
Thomas Hunt Morgan was an American evolutionary biologist, geneticist and embryologist and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries relating the role the chromosome plays in heredity.Morgan received his PhD from Johns Hopkins University in zoology...

 began his work on D. melanogaster and reported his first finding of a white (eyed) mutant in 1910 to the academic community. He was in search of a model organism to study genetic heredity and required a species that could randomly acquire genetic mutation that would visibly manifest as morphological changes in the adult animal. His work on Drosophila earned him the 1933 Nobel Prize
Nobel Prize
The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...

 in Medicine for identifying chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...

s as the vector of inheritance for genes. This and other Drosophila species are widely used in studies of genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

, embryogenesis
Drosophila embryogenesis
Drosophila embryogenesis, the process by which Drosophila embryos form, is a favorite model system for geneticists and developmental biologists studying embryogenesis. The small size, short generation time, and large brood size make it ideal for genetic studies. Transparent embryos facilitate...

, and other areas.

However, some species of Drosophila are difficult to culture in the laboratory, often because they breed on a single specific host in the wild. For some it can be done with particular recipes for rearing media, or by introducing chemicals such as sterols that are found in the natural host; for others it is (so far) impossible. In some cases, the larvae can develop on normal Drosophila lab medium but the female will not lay eggs; for these it is often simply a matter of putting in a small piece of the natural host to receive the eggs. The Drosophila Stock Center in San Diego maintains cultures of hundreds of species for researchers.

Predators


Drosophila are prey for many generalist predators such as robber flies
Asilidae
Insects in the Diptera family Asilidae are commonly called robber flies. The family Asilidae contains about 7,100 described species worldwide....

. In Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

, the introduction of yellowjackets
Vespula
Vespula is a small genus of social wasps, widely distributed in the Northern Hemisphere. Along with members of their sister genus Dolichovespula, they are collectively known by the common name yellowjackets in North America...

 from the mainland United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 has led to the decline of many of the large species. The larvae are preyed on by other fly larvae, staphylinid beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...

s, and ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...

s.

Systematics


The genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Drosophila as currently defined is paraphyletic (see below) and contains 1,450 described species, while the estimated total number of species is estimated at thousands. The majority of the species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 are members of two subgenera: Drosophila (~1,100 species) and Sophophora
Sophophora
The paraphyletic subgenus Sophophora of the genus Drosophila was first described by Alfred Sturtevant in 1939. It contains the best known drosophilid species, Drosophila melanogaster. Sophophora translates as carrier of wisdom...

(including D. (S.) melanogaster
Drosophila melanogaster
Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...

; ~330 species). The Hawaiian species of Drosophila (estimated to be more than 500, with ~380 species described) are sometimes recognized as a separate genus or subgenus, Idiomyia, but this is not widely accepted. About 250 species are part of the genus Scaptomyza, which arose from the Hawaiian Drosophila and later re-colonized continental areas.

Evidence from phylogenetic studies suggests that the following genera arose from within the genus Drosophila:
  • Liodrosophila Duda, 1922
  • Mycodrosophila Oldenburg, 1914
  • Samoaia Malloch, 1934
  • Scaptomyza Hardy, 1849
  • Zaprionus Coquillett, 1901
  • Zygothrica Wiedemann, 1830
  • Hirtodrosophila Duda, 1923 (position uncertain)


Several of the subgeneric and generic names are based on anagrams of Drosophila, including Dorsilopha, Lordiphosa, Siphlodora, Phloridosa and Psilodorha.
Further information: List of Drosophila species

Drosophila species genome project


Drosophila are extensively used as a model organism in genetics (including population genetics), cell-biology, biochemistry, and especially developmental biology. Therefore, extensive efforts are made to sequence drosphilid genomes. The genomes of the following species have been fully or partially sequenced so far:
  • Drosophila (Sophophora) melanogaster
    Drosophila melanogaster
    Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...

  • Drosophila (Sophophora) simulans
    Drosophila simulans
    Drosophila simulans is a species of fly closely related to D. melanogaster and which belongs to the same melanogaster species subgroup. Its closest relatives are D. mauritiana and D. sechellia...

  • Drosophila (Sophophora) sechellia
    Drosophila melanogaster species subgroup
    The Drosophila melanogaster species subgroup contains 9 species, including the best known species Drosophila melanogaster and D. simulans. The subgroup belongs to the Drosophila melanogaster species group within the subgenus Sophophora....

  • Drosophila (Sophophora) yakuba
    Drosophila melanogaster species subgroup
    The Drosophila melanogaster species subgroup contains 9 species, including the best known species Drosophila melanogaster and D. simulans. The subgroup belongs to the Drosophila melanogaster species group within the subgenus Sophophora....

  • Drosophila (Sophophora) erecta
    Drosophila melanogaster species subgroup
    The Drosophila melanogaster species subgroup contains 9 species, including the best known species Drosophila melanogaster and D. simulans. The subgroup belongs to the Drosophila melanogaster species group within the subgenus Sophophora....

  • Drosophila (Sophophora) ananassae
    Sophophora
    The paraphyletic subgenus Sophophora of the genus Drosophila was first described by Alfred Sturtevant in 1939. It contains the best known drosophilid species, Drosophila melanogaster. Sophophora translates as carrier of wisdom...

  • Drosophila (Sophophora) pseudoobscura
    Drosophila pseudoobscura
    Drosophila pseudoobscura is a species of fruit fly, used extensively in lab studies of speciation.In 2005, D. pseudoobscura was the second Drosophila species to have its genome sequenced, after the model organism Drosophila melanogaster....

  • Drosophila (Sophophora) persimilis
  • Drosophila (Sophophora) willistoni
  • Drosophila (Drosophila) mojavensis
  • Drosophila (Drosophila) virilis
  • Drosophila (Drosophila) grimshawi


The data will be used for many purposes, including evolutionary genome comparisons. D. simulans and D. sechellia are sister species, and provide viable offspring when crossed, while D. melanogaster and D. simulans produce infertile hybrid offspring. The Drosophila genome is often compared with the genomes of more distantly related species such as the honeybee Apis mellifera or the mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...

 Anopheles gambiae
Anopheles gambiae
Anopheles gambiae is a complex of at least seven morphologically distinguishable species of mosquitoes in the genus Anopheles. This complex was recognised in the 1960s and includes the most important vectors of malaria in sub-Saharan Africa and the most efficient malaria vectors known.This species...

.

Curated data are available at FlyBase
FlyBase
FlyBase is an online bioinformatics database and the primary repository of genetic and molecular data for the insect family Drosophilidae. For the most extensively studied species and model organism, Drosophila melanogaster, a wide range of data are presented in different formats...

.

External links