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''Drosophila'' () is a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
flies Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced m ...
, belonging to the
family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Drosophilidae The Drosophilidae are a diverse, cosmopolitan family of flies, which includes species called fruit flies, although they are more accurately referred to as vinegar or pomace flies. Another distantly related family of flies, Tephritidae, are true ...
, whose members are often called "small fruit flies" or (less frequently)
pomace Pomace ( ), or marc (; from French ''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. Grape pomace has traditionally been used to pro ...
flies,
vinegar Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains 5–8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to eth ...
flies, or
wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the
Tephritidae The Tephritidae are one of two fly families referred to as fruit flies, the other family being the Drosophilidae. The family Tephritidae does not include the biological model organisms of the genus ''Drosophila'' (in the family Drosophilidae), ...
, a related family, which are also called fruit flies (sometimes referred to as "true fruit flies"); tephritids feed primarily on unripe or ripe
fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
, with many species being regarded as destructive agricultural pests, especially the
Mediterranean fruit fly ''Ceratitis capitata'', commonly known as the Mediterranean fruit fly or medfly, is a yellow-and-brown fly native to sub-Saharan Africa. It has no near relatives in the Western Hemisphere and is considered to be one of the most destructive fr ...
. One species of ''Drosophila'' in particular, ''
D. 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 ...
'', has been heavily used in research in
genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...
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, behavior, and breeding habitat.


Etymology

The term "''Drosophila''", meaning "dew-loving", is a modern scientific
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
adaptation from
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
words , ', "
dew Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening due to condensation. As the exposed surface cools by radiating its heat, atmospheric moisture condenses at a rate greater than that at wh ...
", and , ', "loving" with the Latin feminine suffix ''-a''.


Morphology

''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. 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 long, but some, especially many of the Hawaiian species, are larger than a house fly.


Evolution


Detoxification mechanisms

Environmental challenge by natural toxins helped to prepare ''Drosophila''e to
detox Detoxification or detoxication (detox for short) is the physiological or medicinal removal of toxic substances from a living organism, including the human body, which is mainly carried out by the liver. Additionally, it can refer to the period of ...
DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...
, by shaping the glutathione ''S''-transferase mechanism that metabolizes both.


Selection

The ''Drosophila'' genome is subject to a high degree of selection, especially unusually widespread negative selection compared to other
taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
. A majority of the genome is under selection of some sort, and a supermajority of this is occurring in
non-coding DNA Non-coding DNA (ncDNA) sequences are components of an organism's DNA that do not encode protein sequences. Some non-coding DNA is transcribed into functional non-coding RNA molecules (e.g. transfer RNA, microRNA, piRNA, ribosomal RNA, and regula ...
.
Effective population size The effective population size (''N'e'') is a number that, in some simplified scenarios, corresponds to the number of breeding individuals in the population. More generally, ''N'e'' is the number of individuals that an idealised population w ...
has been credibly suggested to positively correlate with the effect size of both negative and
positive selection In population genetics, directional selection, is a mode of negative natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. Under dir ...
. Recombination is likely to be a significant source of
diversity Diversity, diversify, or diverse may refer to: Business *Diversity (business), the inclusion of people of different identities (ethnicity, gender, age) in the workforce *Diversity marketing, marketing communication targeting diverse customers * ...
. There is evidence that
crossover Crossover may refer to: Entertainment Albums and songs * ''Cross Over'' (Dan Peek album) * ''Crossover'' (Dirty Rotten Imbeciles album), 1987 * ''Crossover'' (Intrigue album) * ''Crossover'' (Hitomi Shimatani album) * ''Crossover'' (Yoshino ...
is positively correlated with polymorphism in ''D.'' populations.


Biology


Habitat

''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. They can be found in
deserts A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
,
tropical rainforest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equa ...
,
cities A city is a human settlement of notable size.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., eds (1996) ''The Social Science Encyclopedia''. 2nd edition. London: Routledge. It can be def ...
, swamps, and alpine zones. Some northern species
hibernate Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...
. The northern species '' D. montana'' is the best cold-adapted, and is primarily found at high altitudes. Most species breed in various kinds of decaying plant and
fungal A fungus ( : fungi or funguses) is any member of the 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, separately from th ...
material, including
fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
, bark,
slime flux Slime flux, also known as bacterial slime or bacterial wetwood, is a bacterial disease of certain trees, primarily elm, cottonwood, poplar, boxelder, ash, aspen, fruitless mulberry and oak. A wound to the bark, caused by pruning, insects, poo ...
es,
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s, and
mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is ...
s. The larvae of at least one species, '' D. suzukii'', can also feed in fresh fruit and can sometimes be a pest. A few species have switched to being
parasites Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
or
predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s. 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 A lek is an aggregation of male animals gathered to engage in competitive displays and courtship rituals, known as lekking, to entice visiting females which are surveying prospective partners with which to mate. A lek can also indicate an avail ...
, conducting courtship in an area separate from breeding sites. Several ''Drosophila'' species, including ''
D. 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 ...
'', '' D. immigrans'', and '' D. simulans'', are closely associated with humans, and are often referred to as
domestic Domestic may refer to: In the home * Anything relating to the human home or family ** A domestic animal, one that has undergone domestication ** A domestic appliance, or home appliance ** A domestic partnership ** Domestic science, sometimes c ...
species. These and other species ('' D. subobscura'', and from a related genus ''
Zaprionus indianus ''Zaprionus indianus'', the African fig fly, is a species of vinegar fly in the family Drosophilidae The Drosophilidae are a diverse, cosmopolitan family of flies, which includes species called fruit flies, although they are more accurately ...
'') 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 A spermatozoon (; also spelled spermatozoön; ; ) 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. (A zygote is a single cell, with a complete set of chromosomes, ...
of any studied organism on Earth, including one species, ''
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—5.8 cm long when uncoiled, over twenty times the entire body length of the male. The cells are mo ...
'', that has sperm cells that are long. 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. ''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 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 aedeagus and injects his sperm through the wound into her abdominal cav ...
. ''Drosophila'' species vary widely in their reproductive capacity. Those such as ''D. melanogaster'' that breed in large, relatively rare resources have
ovaries The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. T ...
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 Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...
s and
microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
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 is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...
, 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. Their median lifespan is 35–45 days.


Mating systems


Courtship behavior

The following section is based on the following ''Drosophila'' species: ''Drosophila simulans'' and ''Drosophila melanogaster''. Courtship behavior of male ''Drosophila'' is an attractive behaviour. Females respond via their perception of the behavior portrayed by the male. Male and female ''Drosophila'' use a variety of sensory cues to initiate and assess courtship readiness of a potential mate. The cues include the following behaviours: positioning, pheromone excretion, following females, making tapping sounds with legs, singing, wing spreading, creating wing vibrations, genitalia licking, bending the stomach, attempt to copulate, and the copulatory act itself. The songs of ''Drosophila melanogaster'' and ''Drosophila simulans'' have been studied extensively. These luring songs are sinusoidal in nature and varies within and between species. The courtship behavior of ''Drosophila melanogaster'' has also been assessed for sex-related genes, which have been implicated in courtship behavior in both the male and female. Recent experiments explore the role of fruitless (''fru'') and doublesex (''dsx''), a group of sex-behaviour linked genes. The
fruitless The ''fruitless'' gene (''fru'') is a ''Drosophila melanogaster'' gene that encodes several variants of a putative transcription factor protein. Normal ''fruitless'' function is required for proper development of several anatomical structures nece ...
(''fru'') gene in ''Drosophila'' helps regulate the network for male courtship behavior; when a mutation to this gene occurs altered same sex sexual behavior in males is observed. Male ''Drosophila'' with the ''fru'' mutation direct their courtship towards other males as opposed to typical courtship, which would be directed towards females. Loss of the ''fru'' mutation leads back to the typical courtship behavior.


Pheromones

A novel class of
pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
s was found to be conserved across the subgenus ''Drosophila'' in 11 desert dwelling species. These pheromones are triacylglycerides that are secreted exclusively by males from their ejaculatory bulb and transferred to females during mating. The function of the pheromones is to make the females unattractive to subsequent suitors and thus inhibit courtship by other males.


Polyandry

The following section is based on the following ''Drosophila'' species: ''
Drosophila serrata ''Drosophila serrata'' is a species of fruit fly in the genus ''Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, ...
'', '' Drosophila pseudoobscura'', ''
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 ...
'', and ''
Drosophila neotestacea ''Drosophila neotestacea'' is a member of the ''testacea'' species group of ''Drosophila''. Testacea species are specialist fruit flies that breed on the fruiting bodies of mushrooms. These flies will choose to breed on psychoactive mushrooms s ...
''.
Polyandry Polyandry (; ) is a form of polygamy in which a woman takes two or more husbands at the same time. Polyandry is contrasted with polygyny, involving one male and two or more females. If a marriage involves a plural number of "husbands and wives ...
is a prominent mating system among ''Drosophila''. Females mating with multiple sex partners has been a beneficial mating strategy for ''Drosophila''. The benefits include both pre and post copulatory mating. Pre-copulatory strategies are the behaviours associated with mate choice and the genetic contributions, such as production of gametes, that are exhibited by both male and female ''Drosophila'' regarding mate choice. Post copulatory strategies include sperm competition, mating frequency, and sex-ratio meiotic drive. These lists are not inclusive.
Polyandry Polyandry (; ) is a form of polygamy in which a woman takes two or more husbands at the same time. Polyandry is contrasted with polygyny, involving one male and two or more females. If a marriage involves a plural number of "husbands and wives ...
among the ''Drosophila pseudoobscura'' in North America vary in their number of mating partners. There is a connection between the number of time females choose to mate and chromosomal variants of the third chromosome. It is believed that the presence of the inverted polymorphism is why re-mating by females occurs. The stability of these polymorphisms may be related to the sex-ratio meiotic drive. However, for ''
Drosophila subobscura ''Drosophila subobscura'' is a species of fruit fly in the family Drosophilidae. Originally found around the Mediterranean, it has spread to most of Europe and the Near East. It has been introduced into the west coasts of Canada, the United Stat ...
,'' the main mating system is monandry, not normally seen in ''Drosophila.''


Sperm competition

The following section is based on the following ''Drosophila'' species: ''Drosophila melanogaster'', ''Drosophila simulans'', and ''Drosophila mauritiana''.
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 ...
is a process that polyandrous ''Drosophila'' females use to increase the fitness of their offspring. The female ''Drosophila'' has two sperm storage organs, the spermathecae and seminal receptacle, that allows her to choose the sperm that will be used to inseminate her eggs. However, some species of ''Drosophila'' have evolved to only use one or the other. Females have little control when it comes to
cryptic female choice Cryptic female choice is a form of mate choice which occurs both in pre and post copulatory circumstances when females in certain species use physical or chemical mechanisms to control a male's success of fertilizing their ova or ovum; i.e. by sele ...
. Female ''Drosophila'' through cryptic choice, one of several post-copulatory mechanisms, which allows for the detection and expelling of sperm that reduces inbreeding possibilities. Manier et al. 2013 has categorized the post copulatory sexual selection of ''Drosophila melanogaster'', ''Drosophila simulans'', and ''Drosophila mauritiana'' into the following three stages: insemination, sperm storage, and fertilizable sperm. Among the preceding species there are variations at each stage that play a role in the natural selection process. This sperm competition has been found to be a driving force in the establishment of reproductive isolation during speciation.


Laboratory-cultured animals

''
D. 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 ...
'' is a popular experimental animal because it is easily cultured en masse out of the wild, has a short generation time, and mutant animals are readily obtainable. In 1906,
Thomas Hunt Morgan Thomas Hunt Morgan (September 25, 1866 – December 4, 1945) was an American evolutionary biologist, geneticist, embryologist, and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries elucidating the role that ...
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 The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...
in Medicine for identifying
chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
s as the vector of inheritance for genes. This and other ''Drosophila'' species are widely used in studies of
genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...
, embryogenesis,
chronobiology Chronobiology is a field of biology that examines timing processes, including periodic (cyclic) phenomena in living organisms, such as their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronob ...
, speciation,
neurobiology Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, developme ...
, 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 Species Stock Center located at
Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to tea ...
in
Ithaca Ithaca most commonly refers to: *Homer's Ithaca, an island featured in Homer's ''Odyssey'' *Ithaca (island), an island in Greece, possibly Homer's Ithaca *Ithaca, New York, a city, and home of Cornell University and Ithaca College Ithaca, Ithaka ...
, New York, maintains cultures of hundreds of species for researchers.


Use in genetic research

''Drosophila'' is considered one of the most impeccable genetic model organisms - they have furthered genetic research unlike any other model organisms. Both adults and embryos are experimental models. . . . ''Drosophila'' is a prime candidate for genetic research because the relationship between human and fruit fly genes is very close. Human and fruit fly genes are so similar, that disease-producing genes in humans can be linked to those in flies. The fly has approximately 15,500 genes on its four chromosomes, whereas humans have about 22,000 genes among their 23 chromosomes. Thus the density of genes per chromosome in ''Drosophila'' is higher than the human genome. Low and manageable number of chromosomes make ''Drosophila'' species easier to study. These flies also carry genetic information and pass down traits throughout generations, much like their human counterparts. The traits can then be studied through different ''Drosophila'' lineages and the findings can be applied to deduce genetic trends in humans. Research conducted on ''Drosophila'' help determine the ground rules for transmission of genes in many organisms. ''Drosophila'' is a useful in vivo tool to analyze Alzheimer's disease.
Rhomboid protease The rhomboid proteases are a family of enzymes that exist in almost all species. They are proteases: they cut the polypeptide chain of other proteins. This proteolytic cleavage is irreversible in cells, and an important type of cellular regulation ...
s were first detected in ''Drosophila'' but then found to be highly conserved across eukaryotes, mitochondria, and
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
. Melanin's ability to protect DNA against ionizing radiation has been most extensively demonstrated in ''Drosophila'', including in the formative study by Hopwood et al 1985.


Microbiome

Like other animals, ''Drosophila'' is associated with various bacteria in its gut. The fly gut microbiota or microbiome seems to have a central influence on ''Drosophila'' fitness and life history characteristics. The microbiota in the gut of ''Drosophila'' represents an active current research field. ''Drosophila'' species also harbour vertically transmitted endosymbionts, such as ''
Wolbachia ''Wolbachia'' is a genus of intracellular bacteria that infects mainly arthropod species, including a high proportion of insects, and also some nematodes. It is one of the most common parasitic microbes, and is possibly the most common reproducti ...
'' and ''
Spiroplasma ''Spiroplasma'' is a genus of Mollicutes, a group of small bacteria without cell walls. ''Spiroplasma'' shares the simple metabolism, parasitic lifestyle, fried-egg colony morphology and small genome of other ''Mollicutes'', but has a distinctiv ...
''. These endosymbionts can act as reproductive manipulators, such as
cytoplasmic incompatibility Cytoplasmic incompatibility (CI) is a phenomenon that results in sperm and eggs being unable to form viable offspring. The effect arises from changes in the gamete cells caused by intracellular parasites like ''Wolbachia'', which infect a wide range ...
induced by ''Wolbachia'' or male-killing induced by the ''D. melanogaster Spiroplasma poulsonii'' (named MSRO). The male-killing factor of the ''D. melanogaster'' MSRO strain was discovered in 2018, solving a decades-old mystery of the cause of male-killing. This represents the first bacterial factor that affects eukaryotic cells in a sex-specific fashion, and is the first mechanism identified for male-killing phenotypes. Alternatively, they may protect theirs hosts from infection. ''Drosophila Wolbachia'' can reduce viral loads upon infection, and is explored as a mechanism of controlling viral diseases (''e.g.'' Dengue fever) by transferring these ''Wolbachia'' to disease-vector mosquitoes. The ''S. poulsonii'' strain of ''
Drosophila neotestacea ''Drosophila neotestacea'' is a member of the ''testacea'' species group of ''Drosophila''. Testacea species are specialist fruit flies that breed on the fruiting bodies of mushrooms. These flies will choose to breed on psychoactive mushrooms s ...
'' protects its host from parasitic wasps and nematodes using toxins that preferentially attack the parasites instead of the host. Since the ''Drosophila'' species is one of the most used model organisms, it was vastly used in genetics. However, the affect
abiotic factors In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them und ...
, such as temperature, has on the
microbiome A microbiome () is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps ''et al.'' as "a characteristic microbial community occupying a reasonably wel ...
on Drosophila species has recently been of great interest. Certain variations in temperature have an impact on the microbiome. It was observed that higher temperatures (31°C) lead to an increase of ''Acetobacter'' populations in the
gut microbiome Gut microbiota, gut microbiome, or gut flora, are the microorganisms, including bacteria, archaea, fungi, and viruses that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the gut ...
of ''
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 ...
'' as compared to lower temperatures (13°C). In low temperatures (13°C), the flies were more cold resistant and also had the highest concentration of ''Wolbachia.'' The microbiome in the gut can also be transplanted among organisms. It was found that ''Drosophila melanogaster'' became more cold-tolerant when the gut microbiota from ''Drosophila melanogaster'' that were reared at low temperatures. This depicted that the gut microbiome is correlated to physiological processes. Moreover, the microbiome plays a role in aggression, immunity, egg-laying preferences, locomotion and
metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...
. As for aggression, it plays a role to a certain degree during courtship. It was observed that germ-free flies were not as competitive compared to the wild-type males. Microbiome of the ''Drosophila'' species is also known to promote aggression by octopamine OA signalling. The microbiome has been shown to impact these fruit flies' social interactions, specifically aggressive behaviour that is seen during
courtship Courtship is the period wherein some couples get to know each other prior to a possible marriage. Courtship traditionally may begin after a betrothal and may conclude with the celebration of marriage. A courtship may be an informal and private m ...
and
mating In biology, mating is the pairing of either opposite- sex or hermaphroditic organisms for the purposes of sexual reproduction. ''Fertilization'' is the fusion of two gametes. ''Copulation'' is the union of the sex organs of two sexually reprod ...
.


Predators

''Drosophila'' species are prey for many generalist predators, such as robber flies. In
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...
, the introduction of
yellowjackets A yellowjacket is a black-and-yellow vespid wasp. Yellowjacket(s) or Yellow Jacket(s) may also refer to: Places * Yellow Jacket, Colorado, an unincorporated town * Yellow Jacket, Florida, an unincorporated area in Dixie County, Florida Arts, e ...
from mainland United States has led to the decline of many of the larger species. The larvae are preyed on by other fly larvae,
staphylinid The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, the ...
beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s, and
ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...
s.


Neurochemistry

As with many Eukaryotes, this genus is known to express
SNARE SNARE proteins – " SNAP REceptor" – are a large protein family consisting of at least 24 members in yeasts, more than 60 members in mammalian cells, and some numbers in plants. The primary role of SNARE proteins is to mediate vesicle f ...
s, and as with several others the components of the SNARE complex are known to be somewhat substitutable: Although the loss of
SNAP-25 Synaptosomal-Associated Protein, 25kDa (SNAP-25) is a Target Soluble NSF (''N''-ethylmaleimide-sensitive factor) Attachment Protein Receptor ( t-SNARE) protein encoded by the ''SNAP25'' gene found on chromosome 20p12.2 in humans. SNAP-25 is a com ...
- a component of neuronal SNAREs - is lethal, SNAP-24 can fully replace it. For another example, an R-SNARE not normally found in synapses can substitute for
synaptobrevin Synaptobrevins (''synaptobrevin isotypes 1-2'') are small integral membrane proteins of secretory vesicles with molecular weight of 18 kilodalton (kDa) that are part of the vesicle-associated membrane protein (VAMP) family. Synaptobrev ...
.


Immunity

The
Spätzle Spätzle (or spaetzle; ) is a type of pasta or dumpling made with eggs, typically serving as a side for meat dishes with gravy. Commonly associated with Swabia, it is also found in the cuisines of southern Germany and Austria, Switzerland, Hung ...
protein is a
ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...
of
Toll Toll may refer to: Transportation * Toll (fee) a fee charged for the use of a road or waterway ** Road pricing, the modern practice of charging for road use ** Road toll (historic), the historic practice of charging for road use ** Shadow toll, ...
. In addition to
melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...
's more commonly known roles in the
endoskeleton An endoskeleton (From Greek ἔνδον, éndon = "within", "inner" + σκελετός, skeletos = "skeleton") is an internal support structure of an animal, composed of mineralized tissue. Overview An endoskeleton is a skeleton that is on the ...
and in
neurochemistry Neurochemistry is the study of chemicals, including neurotransmitters and other molecules such as psychopharmaceuticals and neuropeptides, that control and influence the physiology of the nervous system. This particular field within neuroscience ...
, melanization is one step in the immune responses to some pathogens. Dudzic et al 2019 additionally find a large number of shared
serine protease Serine proteases (or serine endopeptidases) are enzymes that cleave peptide bonds in proteins. Serine serves as the nucleophilic amino acid at the (enzyme's) active site. They are found ubiquitously in both eukaryotes and prokaryotes. Seri ...
messengers between Spätzle/Toll and melanization and a large amount of crosstalk between these pathways.


Systematics

The
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
''Drosophila'' as currently defined is paraphyletic (see below) and contains 1,450 described species, while the total number of species is estimated at thousands. The majority of the
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
are members of two subgenera: ''Drosophila'' (about 1,100 species) and ''
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 (''amphora, p ...
'' (including '' D. (S.) melanogaster''; around 330 species). The Hawaiian species of ''Drosophila'' (estimated to be more than 500, with roughly 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 recolonized continental areas. Evidence from
phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
studies suggests these 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''.


Genetics

''Drosophila'' species are extensively used as model organisms in genetics (including population genetics), cell biology, biochemistry, and especially developmental biology. Therefore, extensive efforts are made to sequence drosphilid genomes. The genomes of these species have been fully sequenced: *'' Drosophila (Sophophora) melanogaster'' *'' Drosophila (Sophophora) simulans'' *'' Drosophila (Sophophora) sechellia'' *'' Drosophila (Sophophora) yakuba'' *'' Drosophila (Sophophora) erecta'' *'' Drosophila (Sophophora) ananassae'' *'' Drosophila (Sophophora) pseudoobscura'' *'' Drosophila (Sophophora) persimilis'' *'' Drosophila (Sophophora) willistoni'' *'' Drosophila (Drosophila) mojavensis'' *'' Drosophila (Drosophila) virilis'' *'' Drosophila (Drosophila) grimshawi'' The data have been 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 Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two dif ...
offspring. The ''Drosophila'' genome is often compared with the genomes of more distantly related species such as the honeybee '' Apis mellifera'' or the mosquito '' Anopheles gambiae''. The modEncode consortium is currently sequencing eight more ''Drosophila'' genomes, and even more genomes are being sequenced by the i5K consortium. Curated data are available at
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 d ...
. The led by Andrew G. Clark,
Michael Eisen Michael Bruce Eisen (born April 13, 1967) is an American computational biologist and the editor-in-chief of the journal eLife. He is a professor of genetics, genomics and development at University of California, Berkeley. He is a leading advocate o ...
, Douglas Smith, Casey Bergman, Brian Oliver, Therese Ann Markow, Thomas Kaufman,
Manolis Kellis , image = Prof Manolis Kellis at the 2017 American Society of Human Genetics meeting in Orlando October 19 2017.jpg , caption = Manolis Kellis at the American Society of Human Genetics (ASHG) meeting in Orlando Florida on October 19, 2017 , bir ...
, William Gelbart, Venky Iyer, Daniel Pollard, Timothy Sackton, Amanda Larracuente, Nadia Singh, and including Wojciech Makalowski,
Mohamed Noor Mohamed Noor is the Interim Dean of Arts & Sciences and a Professor in the Biology Department at Duke University (formerly holding the rotating titles of Earl D. McLean Professor, department chair, and dean of natural sciences). His specialties ...
,
Temple F. Smith Temple Ferris Smith (born March 7, 1939) is an emeritus professor in biomedical engineering who helped to develop the Smith-Waterman algorithm with Michael Waterman in 1981. The Smith-Waterman algorithm serves as the basis for multi sequence comp ...
,
Craig Venter John Craig Venter (born October 14, 1946) is an American biotechnologist and businessman. He is known for leading one of the first draft sequences of the human genome and assembled the first team to transfect a cell with a synthetic chromosome. ...
, Peter Keightley, and
Leonid Boguslavsky Leonid Boguslavsky (born June 17, 1951 Moscow, Soviet Union) is a USSR-born Canadian entrepreneur, scientist and venture capital investor. He was named the Internet investor of the year (Forbes, 2012) and the most successful investor of the year ...
among its contributors presents ten new genomes and combines those with previously released genomes for ''D. melanogaster'' and ''D. pseudoobscura'' to analyse the evolutionary history and common genomic structure of the genus. This includes the discovery of
transposable element A transposable element (TE, transposon, or jumping gene) is a nucleic acid sequence in DNA that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Transp ...
s and illumination of their evolutionary history. Bartolomé et al 2009 find at least of the TEs in ''D. melanogaster'', ''D. simulans'' and ''D. yakuba'' have been acquired by horizontal transfer. They find an average of . Bartolomé also finds HT TEs follow other relatedness metrics, with ''D. melanogaster''⇔''D. simulans'' events being twice as common as either of them ⇔ ''D. yakuba''.


See also

* Drosophila hybrid sterility *
Laboratory experiments of speciation Laboratory experiments of speciation have been conducted for all four modes of speciation: allopatric speciation, allopatric, peripatric speciation, peripatric, parapatric speciation, parapatric, and sympatric speciation, sympatric; and various ot ...
* List of ''Drosophila'' species *''Caenorhabditis'' 'Drosophilae' species supergroup, a group of species generally found on rotten fruits and transported by ''Drosophila'' flies


References


External links

* FlyBase is a comprehensive database for information on the genetics and molecular biology of ''Drosophila''. It includes data from the ''Drosophila'' Genome Projects and data curated from the literature. * is an integrated database of genomic, expression and protein data for ''Drosophila'' * University of California, Santa Cruz ** ** breeds hundreds of species and supplies them to researchers * Lawrence Berkeley National Laboratory ** ** * * * is library of ''Drosophila'' on the web * * – In India microinjection service for the generation of transgenic lines, Screening Platforms, ''Drosophila'' strain development {{Taxonbar, from=Q312154 Drosophilidae genera Taxa named by Carl Fredrik Fallén Animal models