Polyembryony

Last updated

Polyembryony is the phenomenon of two or more embryos developing from a single fertilized egg. [1] [2] [3] Due to the embryos resulting from the same egg, the embryos are identical to one another, but are genetically diverse from the parents. [1] [2] The genetic difference between the offspring and the parents, but the similarity among siblings, are significant distinctions between polyembryony and the process of budding and typical sexual reproduction. [2] Polyembryony can occur in humans, resulting in identical twins, though the process is random and at a low frequency. [1] Polyembryony occurs regularly in many species of vertebrates, invertebrates, and plants.

Contents

Evolution of polyembryony

The evolution of polyembryony and the potential evolutionary advantages that may entail have been studied. In parasitoid wasps, there are several hypotheses surrounding the evolutionary advantages of polyembryony, one of them being that it allows female wasps that are small in size to increase the number of potential offspring in comparison to wasps that are mono embryonic. [4] There are limitations to monoembryony, but with this method of development, multiple embryos can be derived from each of the individual eggs that are laid. [5] [4]

The potential advantages of polyembryony in competing invasive plant species has been studied as well. [6]

Vertebrates

Armadillos are the most well studied vertebrate that undergoes polyembryony, with six species of armadillo in the genus Dasypus that are always polyembryonic. [7] The nine banded armadillo, for instance, always gives birth to four identical young. There are two conditions that are expected to promote the evolution of polyembryony: the mother does not know the environmental conditions of her offspring as in the case of parasitoids, or a constraint on reproduction. [2] It is thought that nine banded armadillos evolved to be polyembryonic because of the latter. [7]

Invertebrates

A colony of wasps Wasp colony.jpg
A colony of wasps

A more striking example of the use of polyembryony as a competitive reproductive tool is found in the parasitoid Hymenoptera, family Encyrtidae. [8] The progeny of the splitting embryo develop into at least two forms, those that will develop into adults and those that become a type of soldier, called precocious larvae. [8] These latter larvae patrol the host and kill any other parasitoids they find with the exception of their siblings, usually sisters. [8]

Obligately polyembryonic insects fall in two classes: Hymenoptera (certain wasps), and Strepsiptera. [9] From one egg, these insects can produce over thousands of offspring. [9] Polyembryonic wasps from the Hymenoptera group can be further subdivided into four families including Braconidae ( Macrocentrus ), Platygastridae ( Platygaster ), Encyrtidae ( Copidosoma ), and Dryinidae. [9]

Polyembryony also occurs in Bryozoa. [2] [10] Through genotype analysis and molecular data, it has been suggested that polyembryony happens in the entire bryozoan order Cyclostomatida. [10]

Plants

The term is also used in botany to describe the phenomenon of seedlings emerging from one embryo. Around 20 genera of gymnospores undergo polyembryony, termed "cleavage polyembryony," where the original zygote splits into many identical embryos. [1] [3] In some plant taxa, the many embryos of polyembryony eventually gives rise to only a single offspring. [1] The mechanism underlying the phenomenon of a resulting single (or in some cases a few) offspring is described in Pinus sylvestris to be programmed cell death (PCD), which removes all but one embryo. [1] Originally, all embryos have equal opportunity to develop into full seeds, but during the early stages of development, one embryo becomes dominant through competition, and therefore the now dormant seed, while the other embryos are destroyed through PCD. [1]

The genus Citrus has a number of species that undergo polyembryony, where multiple nucellar-cell-derived embryos exist alongside sexually-derived embryos. [11] [12] Antonie van Leeuwenhoek first described polyembryony in 1719 when the seed in Citrus was observed to have two germinating embryos. [3] In Citrus, polyembryony is genetically controlled by a shared polyembryony locus among the species, determined by single-nucleotide polymorphism in the genotypes sequenced. [11] The variation within the species of citrus is based on the amount of embryos that develop, the impact of the environment, and gene expression. [12] As with other species, due to the many embryos developing in close proximity, competition occurs, which can cause variation in seed success or vigor. [12]

See also

Related Research Articles

<span class="mw-page-title-main">Asexual reproduction</span> Reproduction without a sexual process

Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent and thus the newly created individual is genetically and physically similar to the parent or an exact clone of the parent. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and bacteria. Many eukaryotic organisms including plants, animals, and fungi can also reproduce asexually. In vertebrates, the most common form of asexual reproduction is parthenogenesis, which is typically used as an alternative to sexual reproduction in times when reproductive opportunities are limited. Komodo dragons and some monitor lizards can reproduce asexually.

<span class="mw-page-title-main">Hymenoptera</span> Order of insects comprising sawflies, wasps, bees, and ants

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 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 — that is, they have a wormlike larval stage and an inactive pupal stage before they reach adulthood.

<span class="mw-page-title-main">Fig wasp</span> Group of mostly pollinating insects whose larvae live in figs

Fig wasps are wasps of the superfamily Chalcidoidea which spend their larval stage inside figs. Some are pollinators but others simply feed off the plant. The non-pollinators belong to several groups within the superfamily Chalcidoidea, while the pollinators are in the family Agaonidae. While pollinating fig wasps are gall-makers, the remaining types either make their own galls or usurp the galls of other fig wasps; reports of their being parasitoids are considered dubious.

<span class="mw-page-title-main">Chalcid wasp</span> Superfamily of wasps

Chalcid wasps are insects within the superfamily Chalcidoidea, part of the order Hymenoptera. The superfamily contains some 22,500 known species, and an estimated total diversity of more than 500,000 species, meaning the vast majority have yet to be discovered and described. The name "chalcid" is often confused with the name "chalcidid", though the latter refers strictly to one constituent family, the Chalcididae, rather than the superfamily as a whole; accordingly, most recent publications (e.g.,) use the name "chalcidoid" when referring to members of the superfamily.

<span class="mw-page-title-main">Parasitoid</span> Organism that lives with its host and kills it

In evolutionary ecology, a parasitoid is an organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionary strategies within parasitism, distinguished by the fatal prognosis for the host, which makes the strategy close to predation.

<span class="mw-page-title-main">Tachinidae</span> Family of insects

The Tachinidae are a large and variable family of true flies within the insect order Diptera, with more than 8,200 known species and many more to be discovered. Over 1,300 species have been described in North America alone. Insects in this family commonly are called tachinid flies or simply tachinids. As far as is known, they all are protelean parasitoids, or occasionally parasites, of arthropods, usually other insects. The family is known from many habitats in all zoogeographical regions and is especially diverse in South America.

<span class="mw-page-title-main">Ichneumonidae</span> Family of wasps

The Ichneumonidae, also known as ichneumon wasps, ichneumonid wasps, ichneumonids, or Darwin wasps, are a family of parasitoid wasps of the insect order Hymenoptera. They are one of the most diverse groups within the Hymenoptera with roughly 25,000 species described as of 2016. However, this likely represents less than a quarter of their true richness as reliable estimates are lacking, along with much of the most basic knowledge about their ecology, distribution, and evolution. It is estimated that there are more species in this family than there are species of birds and mammals combined. Ichneumonid wasps, with very few exceptions, attack the immature stages of holometabolous insects and spiders, eventually killing their hosts. They thus fulfill an important role as regulators of insect populations, both in natural and semi-natural systems, making them promising agents for biological control.

<span class="mw-page-title-main">Thelytoky</span> Type of parthenogenesis in which females are produced from unfertilized eggs

Thelytoky is a type of parthenogenesis and is the absence of mating and subsequent production of all female diploid offspring as for example in aphids. Thelytokous parthenogenesis is rare among animals and reported in about 1,500 species, about 1 in 1000 of described animal species, according to a 1984 study. It is more common in invertebrates, like arthropods, but it can occur in vertebrates, including salamanders, fish, and reptiles such as some whiptail lizards.

<span class="mw-page-title-main">Parasitoid wasp</span> Group of wasps

Parasitoid wasps are a large group of hymenopteran superfamilies, with all but the wood wasps (Orussoidea) being in the wasp-waisted Apocrita. As parasitoids, they lay their eggs on or in the bodies of other arthropods, sooner or later causing the death of these hosts. Different species specialise in hosts from different insect orders, most often Lepidoptera, though some select beetles, flies, or bugs; the spider wasps (Pompilidae) exclusively attack spiders.

<span class="mw-page-title-main">Encyrtidae</span> Family of wasps

Encyrtidae is a large family of parasitic wasps, with some 3710 described species in about 455 genera. The larvae of the majority are primary parasitoids on Hemiptera, though other hosts are attacked, and details of the life history can be variable. They are found throughout the world in virtually all habitats, and are extremely important as biological control agents. They may also present as an ecological threat to the population of some species. For example, the endangered Papilio homerus butterfly is parasitized at a rate of 77%, making them the main contributor to egg mortality in this butterfly species.

<span class="mw-page-title-main">Nucellar embryony</span> Form of seed reproduction

Nucellar embryony is a form of seed reproduction that occurs in certain plant species, including many citrus varieties. Nucellar embryony is a type of apomixis, where eventually nucellar embryos from the nucellus tissue of the ovule are formed, independent of meiosis and sexual reproduction. During the development of seeds in plants that possess this genetic trait, the nucellus tissue which surrounds the megagametophyte can produce nucellar cells, also termed initial cells. These additional embryos (polyembryony) are genetically identical to the parent plant, rendering them as clones. By contrast, zygotic seedlings are sexually produced and inherit genetic material from both parents. Most angiosperms reproduce sexually through double fertilization. Different from nucellar embryony, double fertilization occurs via the syngamy of sperm and egg cells, producing a triploid endosperm and a diploid zygotic embryo. In nucellar embryony, embryos are formed asexually from the nucellus tissue. Zygotic and nucellar embryos can occur in the same seed (monoembryony), and a zygotic embryo can divide to produce multiple embryos. The nucellar embryonic initial cells form, divide, and expand. Once the zygotic embryo becomes dominant, the initial cells stop dividing and expanding. Following this stage, the zygotic embryo continues to develop and the initial cells continue to develop as well, forming nucellar embryos. The nucellar embryos generally end up outcompeting the zygotic embryo, rending the zygotic embryo dormant. The polyembryonic seed is then formed by the many adventitious embryos within the ovule. The nucellar embryos produced via apomixis inherit its mother's genetics, making them desirable for citrus propagation, research, and breeding.

<i>Nasonia vitripennis</i> Species of insect

Nasonia vitripennis is one of four known species under the genus Nasonia - small parasitoid wasps that afflict the larvae of parasitic carrion flies such as blowflies and flesh flies, which themselves are parasitic toward nestling birds. It is the best known and most widely studied of the parasitoid wasps, and their study forms a vital part of the information used to describe the order Hymenoptera, along with information from bees and ants. This parasitoid behaviour makes the wasps an interest for the development of biopesticide and biological systems for controlling unwanted insects.

<span class="mw-page-title-main">Wasp</span> Group of insects

A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The wasps do not constitute a clade, a complete natural group with a single ancestor, as bees and ants are deeply nested within the wasps, having evolved from wasp ancestors. Wasps that are members of the clade Aculeata can sting their prey.

<span class="mw-page-title-main">Evolution of eusociality</span> Origins of cooperative brood care

Eusociality evolved repeatedly in different orders of animals, notably termites and the Hymenoptera. This 'true sociality' in animals, in which sterile individuals work to further the reproductive success of others, is found in termites, ambrosia beetles, gall-dwelling aphids, thrips, marine sponge-dwelling shrimp, naked mole-rats, and many genera in the insect order Hymenoptera. The fact that eusociality has evolved so often in the Hymenoptera, but remains rare throughout the rest of the animal kingdom, has made its evolution a topic of debate among evolutionary biologists. Eusocial organisms at first appear to behave in stark contrast with simple interpretations of Darwinian evolution: passing on one's genes to the next generation, or fitness, is a central idea in evolutionary biology.

<i>Copidosoma</i> Genus of wasps

Copidosoma is a genus of chalcid wasps, which are parasitoids of Lepidoptera. The wasps are polyembryonic, depositing one or two eggs into their host which then develop into multiple offspring and have a soldier caste and a reproductive caste.

Arsenophonus nasoniae is a species of bacterium which was previously isolated from Nasonia vitripennis, a species of parasitoid wasp. These wasps are generalists which afflict the larvae of parasitic carrion flies such as blowflies, houseflies and flesh flies. A. nasoniae belongs to the phylum Pseudomonadota and family Morganellaceae. The genus Arsenophonus, has a close relationship to the Proteus (bacterium) rather than to that of Salmonella and Escherichia. The genus is composed of gammaproteobacterial, secondary-endosymbionts which are gram-negative. Cells are non-flagellated, non-motile, non-spore forming and form long to highly filamentous rods. Cellular division is exhibited through septation. The name 'Arsenophonus nasoniae gen. nov., sp. nov.' was therefore proposed for the discovered bacterium due to its characteristics and its microbial interaction with N. vitripennis. The type strain of A. nasoniae is Strain SKI4.

<i>Copidosoma floridanum</i> Species of wasp

Copidosoma floridanum is a species of wasp in the family Encyrtidae which is primarily a parasitoid of moths in the subfamily Plusiinae. It has the largest recorded brood of any parasitoidal insect, at 3,055 individuals. The life cycle begins when a female oviposits into the eggs of a suitable host species, laying one or two eggs per host. Each egg divides repeatedly and develops into a brood of multiple individuals, a phenomenon called polyembryony. The larvae grow inside their host, breaking free at the end of the host's own larval stage.

<i>Lysiphlebus</i> Genus of wasps

Lysiphlebus is a genus of parasitoid wasps belonging to the family Braconidae.

<i>Ooencyrtus kuvanae</i> Species of chalcid wasp

Ooencyrtus kuvanae is a species of chalcid wasp. It was introduced to North America in 1908 to control Lymantria moths. In North America, it has become an active parasitoid of the invasive spotted lanternfly.

<i>Copidosoma koehleri</i> Species of insect

Copidosoma koehleri belongs to the family Encyrtidae and genus Copidosoma within the order Hymenoptera. It is a parasitoid and its hosts are mainly potato tuber moth but it also infest Andean potato tuber moth, Guatemalan potato tuber moth and Tomato leafminer. Super-parasitism is associated with C. koehleri.

References

  1. 1 2 3 4 5 6 7 Filonva, L. H.; von Arnold, S.; Daniel, G.; Bozhkov, P. V. (2002). "Programmed cell death eliminates all but one embryo in a polyembryonic plant seed". Nature. 9 (10): 1057–1062. doi: 10.1038/sj.cdd.4401068 . PMID   12232793.
  2. 1 2 3 4 5 Craig, Sean F.; Slobodkin, Lawrence B.; Wray, Gregory A.; Biermann, Christiane H. (1997-03-01). "The 'paradox' of polyembryony: A review of the cases and a hypothesis for its evolution". Evolutionary Ecology. 11 (2): 127–143. Bibcode:1997EvEco..11..127C. doi:10.1023/A:1018443714917. ISSN   0269-7653. S2CID   5556785.
  3. 1 2 3 Batygina, T. B.; Vinogradova, G. Iu (2007-05-01). "[Phenomenon of polyembryony. Genetic heterogeneity of seeds]". Ontogenez. 38 (3): 166–191. ISSN   0475-1450. PMID   17621974.
  4. 1 2 Segoli, M.; Harari, A. R.; Rosenheim, J. A.; Bouskila, A.; Keasar, T. (September 2010). "REVIEW: The evolution of polyembryony in parasitoid wasps: The evolution of polyembryony". Journal of Evolutionary Biology. 23 (9): 1807–1819. doi:10.1111/j.1420-9101.2010.02049.x. PMID   20629853. S2CID   22573370.
  5. Strand, Michael R. (2009-01-01), "Chapter 208 - Polyembryony", in Resh, Vincent H.; Cardé, Ring T. (eds.), Encyclopedia of Insects (Second Edition), San Diego: Academic Press, pp. 821–825, ISBN   978-0-12-374144-8 , retrieved 2022-04-10
  6. Blanchard, Megan L.; Barney, Jacob N.; Averill, Kristine M.; Mohler, Charles L.; DiTommaso, Antonio (February 2010). "Does polyembryony confer a competitive advantage to the invasive perennial vine Vincetoxicum rossicum (Apocynaceae)?". American Journal of Botany. 97 (2): 251–260. doi:10.3732/ajb.0900232. PMID   21622385.
  7. 1 2 Loughry, W. J.; Prodöhl, Paulo A.; McDonough, Colleen M.; Avise, John C. (1 January 1998). "Polyembryony in Armadillos: An unusual feature of the female nine-banded armadillo's reproductive tract may explain why her litters consist of four genetically identical offspring". American Scientist. 86 (3): 274–279. doi:10.1511/1998.25.824. JSTOR   27857027.
  8. 1 2 3 E., Beckage, Nancy (1997-01-01). Parasites and pathogens : effects on host hormones and behavior. Chapman & Hall. ISBN   978-0412074011. OCLC   875319486.{{cite book}}: CS1 maint: multiple names: authors list (link)
  9. 1 2 3 Strand, Michael (2009). Encyclopedia of Insects (2nd ed.). Oxford, UK: Elsevier.
  10. 1 2 Jenkins, Helen L.; Waeschenbach, Andrea; Okamura, Beth; Hughes, Roger N.; Bishop, John D. D. (2017-01-17). "Phylogenetically Widespread Polyembryony in Cyclostome Bryozoans and the Protracted Asynchronous Release of Clonal Brood-Mates". PLOS ONE. 12 (1): e0170010. Bibcode:2017PLoSO..1270010J. doi: 10.1371/journal.pone.0170010 . ISSN   1932-6203. PMC   5240946 . PMID   28095467.
  11. 1 2 Nakano, Michiharu; Shimada, Takehiko; Endo, Tomoko; Fujii, Hiroshi; Nesumi, Hirohisa; Kita, Masayuki; Ebina, Masumi; Shimizu, Tokurou; Omura, Mitsuo (2012-02-01). "Characterization of genomic sequence showing strong association with polyembryony among diverse Citrus species and cultivars, and its synteny with Vitis and Populus". Plant Science. 183: 131–142. Bibcode:2012PlnSc.183..131N. doi:10.1016/j.plantsci.2011.08.002. ISSN   1873-2259. PMID   22195586.
  12. 1 2 3 Kishore, Kundan; N., Monika; D., Rinchen; Lepcha, Boniface; Pandey, Brijesh (2012-05-01). "Polyembryony and seedling emergence traits in apomictic citrus". Scientia Horticulturae. 138: 101–107. Bibcode:2012ScHor.138..101K. doi:10.1016/j.scienta.2012.01.035.