Drosophila sechellia | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Diptera |
Family: | Drosophilidae |
Genus: | Drosophila |
Subgenus: | Sophophora |
Species group: | melanogaster |
Species subgroup: | melanogaster |
Species complex: | simulans |
Species: | D. sechellia |
Binomial name | |
Drosophila sechellia Tsacas and Baechli, 1981 | |
Drosophila sechellia is a species of fruit fly, used in lab studies of speciation because it can mate with Drosophila simulans .
Drosophila sechellia is endemic to (some of) the Seychelles, and was one of 12 fruit fly genomes sequenced for a large comparative study. [1]
Drosophila sechellia are known to preferentially lay eggs on toxic Morinda fruits.
The resistance that the D. sechellia shows to the fruit’s toxins is due to its attraction to the ripe Morinda through its octanoic acid. [2] The presence of this fruit is said to help stimulate egg production, which can be attributed to evolutionary adaptive traits. A plausible evolutionary explanation to this attraction is that, upon its arrival in the Seychelles, the ancestor of Drosophila sechellia used a diversity of resources available such as aged, rotten, and nontoxic Morinda fruits. [3]
Research has shown that a mutation in the gene that inhibits egg production is associated with a reduction in L-DOPA; L-DOPA is a precursor of the fertility-regulating hormone dopamine. Morinda fruits are rich in L-DOPA, owing to their usually insecticidal capacities. Drosophila sechellia fertility is reliant on the L-DOPA found in Morinda fruit, and as a result Drosophila sechellia reproduces solely on these toxic fruits. [4] Recent research found that reduced expression of a newly discovered gene, Esterase 6 (Est6), is an important element of the genetic underpinnings behind the adaptation of D. Sechellia to feed on Morinda fruits. [5]
Compared to other species and close relatives, the D. sechellia is found to have lower female adult reproductive potential, as it is shown to produce fewer ovarioles than the D. simulans, but also produces large eggs. [6] This can lead to the evidence in which the evolution of ovoviviparity in D. sechellia is a result to avoid competition and possible exploitation of an unoccupied niche. An evolutionary hypothesis proposed by Mueller & Bitner (2015) is that during the initial phases of ovoviviparity, the more rapidly developing genotypes could not begin development at the peak of octanoic acid concentration despite requiring degradation. This can be due to its tolerance only slightly increasing relative to the other slower developing genotypes. The rapid developing genotypes thus only had a short time to grow on the Morinda fruit before the arrival of other strong larval competitors. [7]
This adaptation to the fresh Morinda fruit would require toleration to the toxins and would make the D. sechellia larvae develop quickly after the eggs were deposited. Its ovoviviparity would ensure that eggs hatch almost immediately in the chosen environment, like a fresh Morinda fruit, and virtually be competitor free until the fruit becomes rotten. The tolerance is a consequence of the changing biotic community in the Morinda fruit as it decays, and expects that such a mutation would accelerate the process of adaptation. [8]
Drosophila is a genus of fly, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the Tephritidae, a related family, which are also called fruit flies ; tephritids feed primarily on unripe or ripe fruit, with many species being regarded as destructive agricultural pests, especially the Mediterranean fruit fly.
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals. It is typical for mammals, but also occurs for some non-mammals. Mammals during pregnancy can have one or more gestations at the same time, for example in a multiple birth.
Drosophila melanogaster is a species of fly in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly", "pomace fly", or "banana fly". In the wild, D. melanogaster are attracted to rotting fruit and fermenting beverages, and are often found in orchards, kitchens and pubs.
Population genetics is a subfield of genetics that deals with genetic differences within and among populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and population structure.
Experimental evolution is the use of laboratory experiments or controlled field manipulations to explore evolutionary dynamics. Evolution may be observed in the laboratory as individuals/populations adapt to new environmental conditions by natural selection.
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 fruit flies because they are frugivorous, and include apple maggot flies and many pests. The best known species of the Drosophilidae is Drosophila melanogaster, within the genus Drosophila, also called the "fruit fly." Drosophila melanogaster is used extensively for studies concerning genetics, development, physiology, ecology and behaviour. Many fundamental biological mechanisms were discovered first in D. melanogaster. The fruit fly is mostly composed of post-mitotic cells, has a very short lifespan, and shows gradual aging. As in other species, temperature influences the life history of the animal. Several genes have been identified that can be manipulated to extend the lifespan of these insects. Additionally, Drosophila subobscura, also within the genus Drosophila, has been reputed as a model organism for evolutionary-biological studies, along with D. sechellia for the evolution of host specialization on the toxic noni fruit and Scaptomyza flava for the evolution of herbivory and specialist on toxic mustard leaves.
Intragenomic conflict refers to the evolutionary phenomenon where genes have phenotypic effects that promote their own transmission in detriment of the transmission of other genes that reside in the same genome. The selfish gene theory postulates that natural selection will increase the frequency of those genes whose phenotypic effects cause their transmission to new organisms, and most genes achieve this by cooperating with other genes in the same genome to build an organism capable of reproducing and/or helping kin to reproduce. The assumption of the prevalence of intragenomic cooperation underlies the organism-centered concept of inclusive fitness. However, conflict among genes in the same genome may arise both in events related to reproduction and altruism.
Brian Charlesworth is a British evolutionary biologist at the University of Edinburgh, and editor of Biology Letters. Since 1997, he has been Royal Society Research Professor at the Institute of Evolutionary Biology (IEB) in Edinburgh. He has been married since 1967 to the British evolutionary biologist Deborah Charlesworth.
Drosophila simulans is a species of fly closely related to D. melanogaster, belonging to the same melanogaster species subgroup. Its closest relatives are D. mauritiana and D. sechellia.
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 mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offspring are sterile. These barriers maintain the integrity of a species by reducing gene flow between related species.
A phene is an individual genetically determined characteristic or trait which can be possessed by an organism, such as eye colour, height, behavior, tooth shape or any other observable characteristic.
Michael R. Rose is a Professor in the Department of Ecology and Evolutionary Biology at the University of California, Irvine.
The concept of a biological species as a group of organisms capable of interbreeding to produce viable offspring dates back to at least the 18th century, although it is often associated today with Ernst Mayr. Species of the fruit-fly Drosophila are one of the most commonly used organisms in evolutionary research, and have been used to test many theories related to the evolution of species. The genus Drosophila comprises numerous species that have varying degrees of premating and postmating isolation between them. These species are useful for testing hypotheses of the reproductive mechanisms underlying speciation.
Population genomics is the large-scale comparison of DNA sequences of populations. Population genomics is a neologism that is associated with population genetics. Population genomics studies genome-wide effects to improve our understanding of microevolution so that we may learn the phylogenetic history and demography of a population.
Martin Edward Kreitman is an American geneticist at the University of Chicago, most well known for the McDonald–Kreitman test that is used to infer the amount of adaptive evolution in population genetic studies.
Recurrent evolution also referred to as repeated or replicated evolution is the repeated evolution of a particular trait, character, or mutation. Most evolution is the result of drift, often interpreted as the random chance of some alleles being passed down to the next generation and others not. Recurrent evolution is said to occur when patterns emerge from this stochastic process when looking across multiple distinct populations. These patterns are of particular interest to evolutionary biologists, as they can demonstrate the underlying forces governing evolution.
Scaptomyza flava is an herbivorous leaf mining fly species in the family Drosophilidae. In Latin, flava means golden or yellow. The fly is amber to dark brown in color and approximately 2.5 mm in length. In Europe and New Zealand the larvae are pests of plants in the order Brassicales, including arugula, brassicas, broccoli, Brussels sprouts, bok choy, cabbage, canola, cauliflower, horseradish, kale, kohlrabi, napa cabbage, nasturtium, radish, rapini, rutabaga, turnip, wasabi and watercress. In New Zealand, its range has expanded to include host species that are intercropped with salad brassicas, including gypsophila, otherwise known as baby's breath, which is in the pink family (Caryophyllaceae) and the pea in the Fabaceae. More typically, S. flava is oligophagous within the Brassicales. Scaptomyza are unusual within the Drospophilidae because the group includes species that are truly herbivorous. Other herbivorous drosophilids include D. suzukii, which attacks fruit very early during ripening and species within the genus Lordiphosa, from Africa and Asia, which also include leaf miners. Most drosophilids feed on microbes associated with decaying vegetation and sap fluxes.
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.
Drosophila metlerri, commonly known as the Sonoran Desert fly, is a fly in the genus Drosophila. The species is found in North America and is most concentrated along the southern coast of California and in Mexico. D. mettleri are dependent on plant hosts, namely, the saguaro and cardon cacti. Thus, they are most prevalent in arid, desert conditions. It is able to detoxify chemicals found in the rotting liquid of cacti hosts, which allows it to use otherwise lethal soil as a nesting site.
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