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 distinctive helical morphology, unlike Mycoplasma. It has a spiral shape and moves in a corkscrew motion. Many Spiroplasma are found either in the gut or haemolymph of insects where they can act to manipulate host reproduction, or defend the host as endosymbionts. Spiroplasma are also disease-causing agents in the phloem of plants. Spiroplasmas are fastidious organisms, which require a rich culture medium. Typically they grow well at 30 °C, but not at 37 °C. A few species, notably Spiroplasma mirum, grow well at 37 °C, and cause cataracts and neurological damage in suckling mice. The best studied species of spiroplasmas are Spiroplasma poulsonii, a reproductive manipulator and defensive insect symbiont, Spiroplasma citri, the causative agent of citrus stubborn disease, and Spiroplasma kunkelii, the causative agent of corn stunt disease.
Meiotic drive is a type of intragenomic conflict, whereby one or more loci within a genome will affect a manipulation of the meiotic process in such a way as to favor the transmission of one or more alleles over another, regardless of its phenotypic expression. More simply, meiotic drive is when one copy of a gene is passed on to offspring more than the expected 50% of the time. According to Buckler et al., "Meiotic drive is the subversion of meiosis so that particular genes are preferentially transmitted to the progeny. Meiotic drive generally causes the preferential segregation of small regions of the genome".
The immigrans-tripunctata radiation is a speciose lineage of Drosophila flies, including over 300 species. The immigrans-tripunctata radiation is a sister lineage to most other members of the subgenus Drosophila. A number of species have had their genomes or transcriptomes sequenced for evolutionary studies using Drosophila.
Drosophila falleni is a species of fly found in northeastern North America. A mycophagous insect, it is known to feed on the fruit bodies (mushrooms) of several genera of fungi, including Agaricus, Amanita, Agrocybe, Boletus, Cortinarius, PluteusGrifola, Polyporus, Hypholoma, Russula, Mycena, Stropharia, and Xerula. The fly can be infested by the parasitic nematode Howardula aoronymphium, which enters the fly larvae when it is feeding on mushrooms.
Drosophila quinaria is a species of fruit fly in the Drosophila quinaria species group. Most Quinaria group species feed largely on mushrooms. However D. quinaria instead eats decaying vegetative matter, a trait it evolved independently.
Howardula aoronymphium is a species of nematode that infects specialist mushroom-feeding fruit flies such as Drosophila falleni and Drosophila neotestacea. Mated female nematodes pierce the fly larva cuticle and take up residence in the hemolymph where they mature alongside the fly. When the adult fly ecloses, the nematode motherworm has reached full size and sheds juvenile nematodes into the hemolymph which are eventually excreted by either the fly anus or ovipositor. Howardula nematodes can severely impact fly egg development, as infection can effectively sterilize some species.
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 such as the Fly Agaric Amanita muscaria. Drosophila neotestacea can be found in temperate regions of North America, ranging from the north eastern United States to western Canada.
Drosophila testacea is a member of the testacea species group of Drosophila. Testacea species are specialist fruit flies that breed on the fruiting bodies of mushrooms. Drosophila testacea can be found in temperate regions of Europe, extending to East Asia. Drosophila testacea and Drosophila orientacea can produce viable hybrids, though they are separated by geography and behavioural barriers. Drosophila testacea females will also readily mate with Drosophila neotestacea males, but viable hybrids are never produced. This hybrid inviability ) may be due to selfish X chromosomes and co-evolved suppressors. Alternately, differences in sex pheromone reception could underlie female readiness and male willingness to copulate.
Drosophila orientacea is a member of the testacea species group of Drosophila. Testacea species are specialist fruit flies that breed on the fruiting bodies of mushrooms. Drosophila orientacea is found in northern Japan on the island of Hokkaido. However, the European species Drosophila testacea and D. orientacea can produce viable hybrids, blurring the level of speciation between the two species. While viable hybrids are produced, extreme behavioural barriers likely prevent mating in the wild. While D. orientacea readily mates with Drosophila neotestacea, viable hybrids are never produced. This hybrid inviability may be due either to issues during copulation, or selfish X chromosomes and co-evolved suppressors.
Spiroplasma poulsonii are bacteria of the genus Spiroplasma that are commonly endosymbionts of flies. These bacteria live in the hemolymph of the flies, where they can act as reproductive manipulators or defensive symbionts.
Drosophila bizonata is a species of fruit fly in the Drosophila bizonata species group in the Immigrans-tripunctata radiation of the Drosophila subgenus. Drosophila bizonata is found in Japan. D. bizonata breeds and feeds exclusively on mushrooms, and has a high tolerance for ibotenic acid, a toxic compound found in Amanita mushrooms.
The Drosophila quinaria species group is a speciose lineage of mushroom-feeding flies studied for their specialist ecology, their parasites, population genetics, and the evolution of immune systems. Quinaria species are part of the Drosophila subgenus.
The Drosophila cardini species group belongs to the subgenus Drosophila of vinegar flies in the Immigrans-tripunctata radiation of the subgenus Drosophila. The closest relatives of Cardini species include Drosophila bizonata, Drosophila quinaria, and Drosophila testacea species groups, comprising mushroom-feeding flies. Cardini group species likely derived their more general feeding ecology from a mushroom-feeding ancestor, an evolutionary transition in feeding similar to Drosophila quinaria.
Mushroom-feeding Drosophila are a subset of Drosophila flies that have highly specific mushroom-breeding ecologies. Often these flies can tolerate toxic compounds from Amanita mushrooms.
Drosophila innubila is a species of vinegar fly restricted to high-elevation woodlands in the mountains of the southern USA and Mexico, which it likely colonized during the last glacial period. Drosophila innubila is a kind of mushroom-breeding Drosophila, and member of the Drosophila quinaria species group. Drosophila innubila is best known for its association with a strain of male-killing Wolbachia bacteria. These bacteria are parasitic, as they drain resources from the host and cause half the infected female's eggs to abort. However Wolbachia may offer benefits to the fly's fitness in certain circumstances. The D. innubila genome was sequenced in 2019.
Jaenimonas drosophilae is a trypanosomatid parasite of mushroom-feeding flies, first characterized in Drosophila neotestacea and Drosophila falleni. Jaenimonas takes up residence in the gut of the fly, and infection leads to reduced fecundity of its fly host. The species is named for John Jaenike, a prominent ecologist and evolutionary biologist whose work on mushroom-feeding flies laid the foundation for studies on mycophagous Drosophila.
Jaenimonas is a genus of trypanosomatid parasite that infects mushroom-feeding Drosophila, similar to Crithidia parasites of Bumblebees. Jaenimonas drosophilae is the sole representative of this genus. The genus is named in honor of John Jaenike, a prominent ecologist and evolutionary biologist whose work on mushroom-feeding flies laid the foundation for studies on mycophagous Drosophila. Jaenike was also an early proponent of the Red Queen hypothesis.
John Jaenike is an ecologist and evolutionary biologist, and currently a professor at the University of Rochester New York. Jaenike was an early proponent of the Red Queen hypothesis, using the idea to explain the maintenance of sex. Jaenike is also known for his extensive work on mushroom-feeding Drosophila and the evolution of their inherited bacterial symbionts Wolbachia and Spiroplasma poulsonii.
The Drosophila bizonata species group is a species group of fruit flies in the subgenus Drosophila.
The Drosophila immigrans species group is a polyphyletic and speciose lineage of Drosophila flies, including over 100 species. Immigrans species belong to the Immigrans-tripunctata radiation of the subgenus Drosophila. Well-described species include Drosophila immigrans, and the sister species Drosophila albomicans and Drosophila nasuta. The genome of D. albomicans was sequenced in 2012 in an effort to characterize novel sex chromosome development in D. albomicans. Immigrans group species are related to mushroom-breeding Drosophila of the Quinaria and Testacea species groups.
