Antennapedia (abbreviated Antp ) is a Hox gene first discovered in Drosophila which controls the formation of legs during development. Loss-of-function mutations in the regulatory region of this gene result in the development of the second leg pair into ectopic antennae . By contrast gain-of-function alleles convert antennae into ectopic legs.
34-518: This is just one illustration of the tendency of organisms to exhibit variations on a theme: modulated repetition. Legs and antennae are related to one another as much as molars are to incisors, fingers are to toes, and arms are to legs. Antp also refers to a gene complex (ANT-C) in Drosophila ending with the Antp gene. It is responsible for formation and differentiation of the thoracic and head segments of
68-411: A considerable number, keeping the wings gripped together especially tightly. Hymenopteran wings have relatively few veins compared with many other insects, especially in the smaller species. In the more ancestral hymenopterans, the ovipositor is blade-like, and has evolved for slicing plant tissues. In the majority, however, it is modified for piercing, and, in some cases, is several times the length of
102-409: A wide range of feeding habits. The most primitive forms are typically phytophagous, feeding on flowers, pollen, foliage, or stems. Stinging wasps are predators, and will provision their larvae with immobilised prey, while bees feed on nectar and pollen . A huge number of species are parasitoids as larvae. The adults inject the eggs into a host, which they begin to consume after hatching. For example,
136-399: Is determined by the number of chromosomes an individual possesses. Fertilized eggs get two sets of chromosomes (one from each parent's respective gametes ) and develop into diploid females, while unfertilized eggs only contain one set (from the mother) and develop into haploid males. The act of fertilization is under the voluntary control of the egg-laying female, giving her control of
170-509: Is known that Antp -class homeobox genes play some sort of role in transcriptional processes, not all of their actions and functions have been discovered. Recent studies observed Antp and the Hox ortholog HoxC6 in Xenopus in order to further distinguish the evolution of these orthologues. HoxC6 was found to play an important role in gastrulation in the vertebrate Xenopus . However, gastrulation
204-577: The Triassic , with the oldest fossils belonging to the family Xyelidae . Social hymenopterans appeared during the Cretaceous . The evolution of this group has been intensively studied by Alex Rasnitsyn , Michael S. Engel , and others. Phylogenetic relationships within the Hymenoptera, based on both morphology and molecular data, have been intensively studied since 2000. In 2023, a molecular study based on
238-1012: The forewings by a series of hooks . Thus, another plausible etymology involves Hymen , the Ancient Greek god of marriage, as these insects have married wings in flight. Another suggestion for the inclusion of Hymen is the myth of Melissa , a nymph with a prominent role at the wedding of Zeus. Molecular analysis finds that Hymenoptera is the earliest branching group of Holometabola . Hymenoptera (sawflies, wasps) [REDACTED] Coleoptera (beetles) [REDACTED] Strepsiptera (twisted-wing parasites) [REDACTED] Raphidioptera (snakeflies) [REDACTED] Megaloptera (alderflies and allies) [REDACTED] Neuroptera (Lacewings and allies) [REDACTED] Lepidoptera (butterflies, moths) [REDACTED] Trichoptera (caddisflies) [REDACTED] Diptera [REDACTED] Mecoptera (scorpionflies) [REDACTED] Siphonaptera (fleas) [REDACTED] Hymenoptera originated in
272-402: The genetic load of deleterious genes is purged relatively quickly. Some hymenopterans take advantage of parthenogenesis , the creation of embryos without fertilization . Thelytoky is a particular form of parthenogenesis in which female embryos are created (without fertilisation). The form of thelytoky in hymenopterans is a kind of automixis in which two haploid products (proto-eggs) from
306-408: The scutellum ; the cervix , a membrane that separates the head from the thorax; and the pleuron , a lateral sclerite of the thorax. In dragonflies and damselflies the mesothorax and metathorax are fused together to form the synthorax . In some insect pupae, like the mosquitoes ', the head and thorax can be fused in a cephalothorax . Members of suborder Apocrita (wasps, ants and bees) in
340-493: The Cape honey bee Apis mellifera capensis . Oocytes that undergo automixis with central fusion often have a reduced rate of crossover recombination , which helps to maintain heterozygosity and avoid inbreeding depression . Species that display central fusion with reduced recombination include the ants Platythyrea punctata and Wasmannia auropunctata and the Cape honey bee Apis mellifera capensis . In A. m. capensis ,
374-826: The analysis of ultra-conserved elements confirmed many previous findings and produced a relatively robust phylogeny of the whole Order. Basal superfamilies are shown in the cladogram below. Tenthredinoidea [REDACTED] Xyeloidea ( Triassic -present) [REDACTED] Pamphilioidea [REDACTED] Siricoidea (horntails or wood wasps) [REDACTED] Xiphydrioidea (wood wasps) [REDACTED] Cephoidea (stem sawflies) [REDACTED] Orussoidea ( parasitic wood wasps) [REDACTED] Apocrita ( ants , bees , wasps ) [REDACTED] Hymenopterans range in size from very small to large insects, and usually have two pairs of wings. Their mouthparts are adapted for chewing, with well-developed mandibles (ectognathous mouthparts). Many species have further developed
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#1732851302274408-429: The body. In some species, the ovipositor has become modified as a stinger , and the eggs are laid from the base of the structure, rather than from the tip, which is used only to inject venom . The sting is typically used to immobilize prey, but in some wasps and bees may be used in defense. Hymenopteran larvae typically have a distinct head region, three thoracic segments, and usually nine or 10 abdominal segments. In
442-410: The development of a pair of ectopic legs, resulting in 10-legged mutant spiders. Drosophila Antp is thought to play an important role in the role of ectopic leg or antenna placement, but not in abdominal leg suppression. However, recent research supported that leg suppression was indeed performed by Antp in arachnids. This suggests that spiders and insects may have separately developed strategies of
476-459: The early metazoan era. It is suggested that Antennapedia arose from Evx , a non- Hox family of genes. This duplication event of Evx into the Antp -class probably occurred prior to cnidarian divergence, as there are Cnidarians with Evx and without Hox class genes and vice versa. Recent studies have observed that down-regulation of the Antp gene in Parasteatoda tepidariorum leads to
510-420: The eggs of the endangered Papilio homerus are parasitized at a rate of 77%, mainly by Hymenoptera species. Some species are even hyperparasitoid , with the host itself being another parasitoid insect. Habits intermediate between those of the herbivorous and parasitoid forms are shown in some hymenopterans, which inhabit the galls or nests of other insects, stealing their food, and eventually killing and eating
544-418: The fly's body. The origin of the ancestor homeobox gene is an important aspect of the evolution of the Antp -class Hox genes . Early evolution of the Antp -class genes may have predated the divergence of cnidarians . However, the role that Antp plays in the spatial body development of cnidarians remains unclear. A widely accepted theory is that the ancestor Hox cluster containing three genes arose in
578-421: The importance of the conservation of this gene cluster in the evolution of body morphology. Thorax (insect anatomy) The thorax is the midsection ( tagma ) of the hexapod body ( insects and entognathans ). It holds the head, legs , wings and abdomen . It is also called mesosoma or cephalothorax in other arthropods. It is formed by the prothorax , mesothorax and metathorax and comprises
612-403: The leg suppression via the evolutionary pressure of convergence. Arachnids' Antp gene is different from other Antp Hox clusters, suggesting that it has evolved via a divergence event leading to the development on the leg suppression function. This example suggests how the functions of homeobox genes including Antp have evolved over time to account for different lineages' needs. Although it
646-417: The mouthparts into a lengthy proboscis , with which they can drink liquids, such as nectar . They have large compound eyes , and typically three simple eyes, ocelli . The forward margin of the hind wing bears a number of hooked bristles, or " hamuli ", which lock onto the fore wing, keeping them held together. The smaller species may have only two or three hamuli on each side, but the largest wasps may have
680-473: The multiple origins of eusociality within this order. In many colonies of bees, ants, and wasps, worker females will remove eggs laid by other workers due to increased relatedness to direct siblings, a phenomenon known as worker policing . Another consequence is that hymenopterans may be more resistant to the deleterious effects of inbreeding . As males are haploid, any recessive genes will automatically be expressed, exposing them to natural selection. Thus,
714-516: The occupant. The Hymenoptera are divided into two groups; the Symphyta which have no waist, and the Apocrita which have a narrow waist. The suborder Symphyta includes the sawflies , horntails , and parasitic wood wasps . The group may be paraphyletic , as it has been suggested that the family Orussidae may be the group from which the Apocrita arose. They have an unconstricted junction between
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#1732851302274748-556: The order Hymenoptera have the first segment of the abdomen fused with the thorax, which is called the propodeum . The head is connected to the thorax by the occipital foramen , enabling a wide range of motion for the head. In most flying insects, the thorax allows for the use of asynchronous muscles . Hymenoptera Hymenoptera is a large order of insects , comprising the sawflies , wasps , bees , and ants . Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of
782-422: The recombination rate during meiosis is reduced more than tenfold. In W. auropunctata the reduction is 45 fold. Single queen colonies of the narrow headed ant Formica exsecta illustrate the possible deleterious effects of increased homozygosity. Colonies of this species which have more homozygous queens will age more rapidly, resulting in reduced colony survival. Different species of Hymenoptera show
816-413: The same meiosis fuse to form a diploid zygote. This process tends to maintain heterozygosity in the passage of the genome from mother to daughter. It is found in several ant species including the desert ant Cataglyphis cursor , the clonal raider ant Cerapachys biroi , the predaceous ant Platythyrea punctata , and the electric ant (little fire ant) Wasmannia auropunctata . It also occurs in
850-615: The sex locus and develop as a male, instead. This is especially likely to occur in an individual whose parents were siblings or other close relatives. Diploid males are known to be produced by inbreeding in many ant, bee, and wasp species. Diploid biparental males are usually sterile but a few species that have fertile diploid males are known. One consequence of haplodiploidy is that females on average have more genes in common with their sisters than they do with their daughters. Because of this, cooperation among kindred females may be unusually advantageous and has been hypothesized to contribute to
884-417: The sex of her offspring. This phenomenon is called haplodiploidy . However, the actual genetic mechanisms of haplodiploid sex determination may be more complex than simple chromosome number. In many Hymenoptera, sex is determined by a single gene locus with many alleles. In these species, haploids are male and diploids heterozygous at the sex locus are female, but occasionally a diploid will be homozygous at
918-403: The species are parasitic . Females typically have a special ovipositor for inserting eggs into hosts or places that are otherwise inaccessible. This ovipositor is often modified into a stinger . The young develop through holometabolism (complete metamorphosis )—that is, they have a wormlike larval stage and an inactive pupal stage before they reach adulthood. The name Hymenoptera refers to
952-438: The suborder Symphyta , the eruciform larvae resemble caterpillars in appearance, and like them, typically feed on leaves. They have large chewing mandibles, three pairs of thoracic limbs, and, in most cases, six or eight abdominal prolegs . Unlike caterpillars, however, the prolegs have no grasping spines, and the antennae are reduced to mere stubs. Symphytan larvae that are wood borers or stem borers have no abdominal legs and
986-399: The suborder (and clade) Apocrita , characterized by a constriction between the first and second abdominal segments called a wasp-waist ( petiole ), also involving the fusion of the first abdominal segment to the thorax . Also, the larvae of all Apocrita lack legs, prolegs, or ocelli. The hindgut of the larvae also remains closed during development, with feces being stored inside the body, with
1020-427: The thoracic legs are smaller than those of non-borers. With rare exceptions, larvae of the suborder Apocrita have no legs and are maggotlike in form, and are adapted to life in a protected environment. This may be the body of a host organism, or a cell in a nest, where the adults will care for the larva. In parasitic forms, the head is often greatly reduced and partially withdrawn into the prothorax (anterior part of
1054-514: The thorax and abdomen. The larvae are herbivorous, free-living, and eruciform , usually with three pairs of true legs, prolegs (on every segment, unlike Lepidoptera ) and ocelli . The prolegs do not have crochet hooks at the ends unlike the larvae of the Lepidoptera. The legs and prolegs tend to be reduced or absent in larvae that mine or bore plant tissue, as well as in larvae of Pamphiliidae . The wasps , bees , and ants together make up
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1088-524: The thorax). Sense organs appear to be poorly developed, with no ocelli, very small or absent antennae, and toothlike, sicklelike, or spinelike mandibles. They are also unable to defecate until they reach adulthood due to having an incomplete digestive tract (a blind sac), presumably to avoid contaminating their environment. The larvae of stinging forms ( Aculeata ) generally have 10 pairs of spiracles, or breathing pores, whereas parasitic forms usually have nine pairs present. Among most or all hymenopterans, sex
1122-458: The wings of the insects, but the original derivation is ambiguous. All references agree that the derivation involves the Ancient Greek πτερόν ( pteron ) for wing. The Ancient Greek ὑμήν ( hymen ) for membrane provides a plausible etymology for the term because species in this order have membranous wings. However, a key characteristic of this order is that the hindwings are connected to
1156-568: Was also a target in the Drosophila Antp gene. The anterior–posterior pattern mechanism is highly conserved in these genes, as its function in Xenopus is clear, but it is unclear why it would be a target in Drosophila . The similarities continuously observed between Hox genes in vertebrates and Drosophila suggests a complex evolutionary history of the Antp Hox gene cluster, as well as reaffirms
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