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,
tropical rainforest,
cities,
swamps, and
alpine zones. Some northern species
hibernate. The northern species
D. montana is the best cold-adapted, and is primarily found at high latitudes or high altitudes. 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. 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 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. Several
Drosophila species, including
D. 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) 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 of any studied organism on Earth, including one species,
D. bifurca, 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.
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. Their median lifespan is 35–45 days.
Aging DNA damage accumulates in
Drosophila intestinal
stem cells with age. Deficiencies in the
Drosophila DNA damage response, including deficiencies in expression of genes involved in
DNA damage repair, accelerates intestinal stem cell (
enterocyte) aging. Sharpless and Depinho reviewed evidence that stem cells undergo intrinsic aging and speculated that stem cells grow old, in part, as a result of DNA damage.
Mating systems Courtship behavior The following is based on
D. simulans and
D. 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 secretion, 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. 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. 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:
D. serrata,
D. pseudoobscura,
D. melanogaster, and
D. neotestacea.
Polyandry is a prominent mating system among
Drosophila. Females mating with multiple sex partners has been a beneficial mating strategy for
Drosophila.
Sperm competition The following section is based on the following
Drosophila species:
D. melanogaster,
D. simulans, and
D. mauritiana.
Sperm competition 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. Females have little control when it comes to
cryptic female choice.
Parthenogenesis and gynogenesis Parthenogenesis does not occur in
D. melanogaster, but in the
gyn-f9 mutant,
gynogenesis occurs at low frequency. The natural populations of
D. mangebeirai are entirely female, making it the only obligate parthenogenetic species of Drosophila. Parthenogenesis is facultative in
parthenogenetica and
mercatorum.
Laboratory-cultured animals D. melanogaster 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 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 in Medicine for identifying
chromosomes as the vector of inheritance for genes. This and other
Drosophila species are widely used in studies of
genetics,
embryogenesis,
chronobiology,
speciation,
neurobiology, and other areas. The
Drosophila Species Stock Center located at
Cornell University in
Ithaca, New York, maintains cultures of hundreds of species for researchers.
Use in genetic research Drosophila is considered one of the most valuable genetic model organisms; both adults and embryos are used in experiments. Compared to
vertebrate model animals, they reproduce faster and are easier to keep.
Drosophilia is also easy to study genetically due to its low number of chromosomes and the large number of mutations that can produce easily-visible variations in appearance. Genetic traits can be studied through different
Drosophila lineages, and the findings can be applied to deduce genetic trends in humans. Using
Drosophilia, Thomas Hunt Morgan discovered that genes are found on chromosomes and greatly refined Mendel's theory of inheritance. These rules apply to many organisms, including humans. As much as 75% of human disease-producing genes have counterparts (
orthologs) in
Drosophilia, making it useful for studying many diseases.
Drosophila is a useful in vivo tool to analyze Alzheimer's disease.
Rhomboid proteases were first detected in
Drosophila but then found to be
highly conserved across
eukaryotes,
mitochondria, and
bacteria. 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. in 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 and
Spiroplasma. These endosymbionts can act as reproductive manipulators, such as
cytoplasmic incompatibility 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 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 effect
abiotic factors, such as temperature, has on the
microbiome 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 of
D. melanogaster 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
D. melanogaster became more cold-tolerant when the gut microbiota from
D. 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. 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 and
mating.
Predators Drosophila species are prey for many generalist predators, such as
robber flies. In
Hawaii, the introduction of
yellowjackets 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 beetles, and
ants.
Neurochemistry Fruit flies use several fast-acting neurotransmitters, similar to those found in humans, which allow neurons to communicate and coordinate behavior. Acetylcholine, glutamate, gamma-aminobutyric acid (GABA), dopamine, serotonin, and histamine are all neurotransmitters that can be found in humans, but
Drosophila also have another neurotransmitter,
octopamine, the analog of norepinephrine. Acetylcholine is the primary excitatory neurotransmitter and GABA is the primary inhibitory neurotransmitter utilized in the drosophila central nervous system. In
Drosophila, the effects of many neurotransmitters can vary depending on the receptors and signaling pathways involved, allowing them to act as excitatory or inhibitory signals under different contexts. This versatility enables complex neural processing and behavioral flexibility. Glutamate can serve as an excitatory neurotransmitter, specifically at the neuromuscular junction in fruit flies. This differs from vertebrates, where acetylcholine is used at these junctions. In
Drosophila, histamine primarily functions as a neurotransmitter in the visual system. It is released by photoreceptor cells to transmit visual information from the eye to the brain, making it essential for vision. As with many eukaryotes,
Drosophila express
SNAREs, and as with several others the components of the SNARE complex are known to be somewhat substitutable: Although the loss of
SNAP-25 - 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.
Immunity The
Spätzle protein is a
ligand of
Toll. In addition to
melanin's more commonly known roles in the
endoskeleton and in
neurochemistry, melanization is one step in the immune responses to some pathogens. Dudzic
et al. (2019) additionally find a large number of shared
serine protease messengers between Spätzle/Toll and melanization and a large amount of
crosstalk between these pathways. ==Systematics==