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Bdelloidea

October 15, 2023

For the mite superfamily, see Bdelloidea (mite).

Bdelloidea /ˈdɛlɔɪdiə/ (Greek βδέλλα, bdella, "leech") is a class of rotifers found in freshwater habitats all over the world. There are over 450 described species of bdelloid rotifers (or 'bdelloids'),[1] distinguished from each other mainly on the basis of morphology.[2] The main characteristics that distinguish bdelloids from related groups of rotifers are exclusively parthenogenetic reproduction and the ability to survive in dry, harsh environments by entering a state of desiccation-induced dormancy (anhydrobiosis) at any life stage.[3] They are often referred to as "ancient asexuals" due to their unique asexual history that spans back to over 25 million years ago through fossil evidence.[4] Bdelloid rotifers are microscopic organisms, typically between 150 and 700 µm in length.[3] Most are slightly too small to be seen with the naked eye, but appear as tiny white dots through even a weak hand lens, especially in bright light. In June 2021, biologists reported the restoration of bdelloid rotifers after being frozen for 24,000 years in the Siberian permafrost.[5]

Bdelloid rotifers
Temporal range: Miocene–present
SEM showing morphological variation of bdelloid rotifers and their jaws
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Rotifera
Superclass: Eurotatoria
Class: Bdelloidea
Hudson, 1884

Evolutionary relationships Edit

The phylum Rotifera traditionally included three classes: Bdelloidea, Monogononta and Seisonidea.[6] Prior to 1990, phylogenetic studies based on morphology seemed to indicate that the sister group to bdelloid rotifers was Monogononta, with seisonid rotifers as an early-diverging outgroup.[7]

 
Cladograms showing alternative possible relationships within Syndermata (or Rotifera). Transcriptome results published in 2014 [8] support a refined version of the scenario in the bottom left, with Bdelloidea as a sister group to Seisonidea + Acanthocephala, and Monogononta as an outgroup. Cladograms modified from Fig. 3, Lasek-Nesselquist 2012.[9]

Modern molecular phylogenetic studies demonstrate that this classic understanding of 'Rotifera' is incomplete (paraphyletic), because it omits a fourth clade of closely related organisms: the Acanthocephala, or thorny-headed worms.[10] Originally classified as a separate phylum, molecular and morphological evidence accumulated between 1994 and 2014 to indicate that Acanthocephala forms a monophyletic group with Bdelloidea, Monogononta and Seisonidea.[8][11] To accommodate this finding, some authors extend the term 'Rotifera' to include the highly modified, parasitic 'acanthocephalan rotifers' alongside bdelloid, monogonont and seisonid rotifers.[12] Others refer to the grouping of the four taxa as Syndermata, a term derived from their shared syncytial epidermis.[11]

The position of Bdelloidea within Syndermata (or Rotifera) is not entirely clear. Alternative possible phylogenetic relationships within the clade are illustrated by the accompanying cladograms. As of 2014, the "most comprehensive phylogenomic analysis of syndermatan relationships" to date was based on transcriptome data from all four groups,[8] and provided "strong support" for the hypothesis illustrated in the bottom left of the figure, in which Seisonidea and Acanthocephala are sister taxa. The study further indicated that the sister group to this taxon is Bdelloidea, whereas Monogononta is the outgroup to all three. This would mean that the closest living relatives of bdelloid rotifers are not monogonont rotifers, as previously believed, but seisonid rotifers and acanthocephalans, despite their highly modified morphology.

Classification and identification Edit

Bdelloidea is a class of the phylum Rotifera, consisting of three orders: Philodinavida, Philodinida and Adinetida.[13] These orders are divided into four families and about 450 species.[14] Since these organisms are asexual the usual definition of a species as a group of organisms capable of creating fertile offspring is inapplicable, therefore the species concept in these organisms is based on a mixture of morphological and molecular data instead. DNA studies suggest that the diversity is much greater than the original morphological classifications suggest.[15][16]

Bdelloids can only be identified by eye while they are alive because many of the characteristics significant to classification are related to feeding and crawling; however, genetic identification of bdelloids is possible on dead individuals. Once preserved, the individuals contract into "blobs" which restricts analysis.[17] There are currently three morphological identification methodologies, two of which are considered dated: Bartoš (1951)[18] and Donner (1965).[14] The third method is a diagnostic key developed in 1995 by Shiel.[17]

Morphology Edit

 
Figure 1: SEM pictures of some species of the genus Rotaria with head (red), tail (white) and trunk (blue) areas highlighted

There are three main regions of the body of bdelloids: head, trunk and foot. The adjacent image depicts each area to show how body parts can be very different although they are named the same depending on the species involved. Bdelloids typically have a well-developed corona, divided into two parts, on a retractable head.

Some identifiable features of the bdelloids include :

  • Well-developed foot glands[17]
  • A mouth opening with a long oesophagus[17]
  • Strong teeth (labelled by a tooth index)[17]
  • Many cilia[17]
  • Species-specific upper lip shape[17]
  • Order-specific corona type[3]
    • Philodinida consist of two ciliated discs
    • Adinetida consist of a ventral ciliated field
    • Philodinavida have a small corona

The bdelloid digestive and reproductive systems can be found within the trunk sections of their bodies, with the stomach being the most visible of the organs. In certain genera, (Habrotrocha, Otostephanos and Scepanotrocha) the bdelloid can actually be identified by the appearance of distinct spherical pellets within the stomach, which will be released as faeces. These pellets are a distinguishing characteristic since all the other genera release faeces as loose material.[3]

Most bdelloids retract the foot while they eat, but there are four genera that lack a foot: Adineta, Bradyscela, Henoceros and Philodinavus. This affects not only how they feed but also how they crawl; for instance Adineta and Bradyscela slide whereas the other genera loop.[3]

Behaviour Edit

A bdelloid feeding

The behaviour of bdelloids can be split into four categories: feeding, locomotion, reproduction and stress-induced behaviours.

Feeding Edit

The specific feeding behaviour of bdelloids is varied but most use rings of cilia in the corona organ to create currents of water which blow food through the mouth to the mastax organ which has been adapted specifically for grinding food.[19] Food includes suspended bacteria, algae, detritus, and other things.

Locomotion Edit

There appear to be three main methods of movement: free swimming, inch-worming along a substrate, or sessility. Inch-worming (or crawling) involves taking alternate steps with the head and tail, as do certain leeches, which gives the group their name (Greek βδέλλα or bdella, meaning leech). This video demonstrates how bdelloids move in three different situations: locomotion and feeding of bdelloid rotifers.

Reproduction Edit

Bdelloids are of interest in the study of the evolution of sex because a male has never been observed,[20] and females reproduce exclusively by parthenogenesis, a form of asexual reproduction where embryos grow and develop without the need for fertilization; this is akin to the apomixis seen in some plants.[21] Each individual has paired gonads. Despite having been asexual for millions of years, they have diversified into more than 450 species and are fairly similar to other sexually reproducing rotifer species.

However, a new study provided evidence for interindividual genetic exchange and recombination in Adineta vaga, a species previously thought to be anciently asexual.[22]

Adineta vaga is capable of carrying out DNA repair by a nonreductional meiosis.[23] Germline DNA repair occurs in a specific period of oogenesis during which homologous chromosomes take on a meiotic-like juxtaposed configuration.[23] This germline DNA repair results in accurate reconstitution of the genetic material transmitted to offspring.

Evolution of obligate parthenogenetic reproduction Edit

In 2003, the mode of asexual reproduction in the bdelloid rotifers was wholly unknown.[24] One theory of how obligate parthenogenesis arose in bdelloid rotifers was that parthenogenic lineages lost the ability to respond to sex-inducing signal, which is why these lineages retained their asexuality.[25] The obligate parthenogenetic strains of bdelloid rotifers produce a sex-inducing signal but have lost the ability to respond to that signal. It was later discovered that the inability to respond to sex-inducing signals in obligate parthenogens was caused by simple Mendelian inheritance of the gene op. [26]

Stress-induced behaviour Edit

Bdelloids are able to survive environmental stresses by entering a state of dormancy known as anhydrobiosis which enables the organism to rapidly dehydrate and thus resist desiccation. While preparing for this dormant state many metabolic processes are adjusted to equate for the change in state; e.g. the production of protective chemicals.[27] The bdelloid can remain in this state, which is known as a 'xerosome' until the return of a sufficient amount of water, at which point they will rehydrate and become active within hours. Hatching of the young will only occur when conditions are at their most favourable.[28] These forms of dormancy are also known as cryptobiosis or quiescence. Bdelloids have been known to survive in this state for up to 9 years while waiting for favourable conditions to return.[28] In addition to surviving desiccation through anhydrobiosis, desiccation stress on two bdelloid species actually helped to maintain fitness and even improved their species fecundity.[29] The rotifers that were consistently kept hydrated fared worse than those desiccated and rehydrated.[30]

Bdelloidea have evolved a unique mechanism to help overcome one of the major perils of asexual reproduction. According to the Red Queen hypothesis of co-evolution, obligate asexuals will be driven extinct by rapidly changing parasites and pathogens, because they cannot change their genotypes quickly enough to keep up in this never-ending race. In populations of bdelloid rotifers, however, many parasites are destroyed during periods of extended desiccation.[31] Moreover, desiccated bdelloid rotifers are easily blown away from parasite-infested habitats by wind, and establish new, healthy populations elsewhere, which allows them to escape the Red Queen by moving in time and space instead of using sex to change their genotype.[32]

When these creatures recover from desiccation, it has been shown that they undergo a potentially unique genetic process where horizontal gene transfer occurs[citation needed], resulting in a significant proportion of the bdelloid genome, up to 10%, having been obtained through horizontal gene transfer from bacteria, fungi and plants.[33] How and why horizontal gene transfer occur in bdelloids is under much debate at present; particularly with regards to possible connections between the foreign genes and the desiccation process as well as possible connections to bdelloids' ancient asexuality.

When they desiccate completely, their DNA breaks up into many pieces. And when they come back to life after being rehydrated, it creates an opportunity for alien DNA fragments to enter their genome. This process was improved 60 million years ago when they captured a bacterial gene this way, which gave them a new gene regulatory system. The new system was used to keep transposons in check.[34]

Bdelloid rotifers are extraordinarily resistant to damage from ionizing radiation due to the same DNA-preserving adaptations used to survive dormancy.[35] These adaptations include an extremely efficient mechanism for repairing DNA double-strand breaks.[36] This repair mechanism was studied in two Bdelloidea species, Adineta vaga,[36] and Philodina roseola.[37] and appears to involve mitotic recombination between homologous DNA regions within each species.

Horizontal gene transfer Edit

Large-scale horizontal transfer of bacterial, plant and fungal genes into bdelloid rotifers[38] has been documented, and may represent an important factor in bdelloid evolution.

Gallery Edit

  •  

    Lateral view of a bdelloid.

  •  

    Frontal view of a bdelloid's corona.

  •  

    Lateral view of a bdelloid.

  •  

    Lateral view of a bdelloid.

  •  

    Lateral view of a bdelloid in algae-rich water

  •  

    Specimen of the genus Philodina

References Edit

  1. ^ Donner, Josef (1965). "Ordnung Bdelloidea (Rotatoria, Rädertiere)". Bestimmungsbücher zur Bodenfauna Europas, volume 6. Berlin: Akademie Verlag. OCLC 6733231. and Segers, Hendrik (2007). "Annotated checklist of the rotifers (Phylum Rotifera), with notes on nomenclature, taxonomy and distribution". Zootaxa. 1590: 3–104. Abstract.
  2. ^ Segers, Hendrick (2007). Annotated checklist of the rotifers (Phylum Rotifera), with notes on nomenclature, taxonomy and distribution (PDF). Auckland: Magnolia Press. ISBN 978-1-86977-129-4.
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  5. ^ Renault, Marion (7 June 2021). "This Tiny Creature Survived 24,000 Years Frozen in Siberian Permafrost - The microscopic animals were frozen when woolly mammoths still roamed the planet, but were restored as though no time had passed". the New York Times. Retrieved 7 June 2021.
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  19. ^ Klusemann, J.; Kleinow, W.; Peters, W. (1990). "The hard parts (trophi) of the rotifer mastax do contain chitin: evidence from studies on Brachionus plicatilis". Histochem. Cell Biol. 94 (3): 277–283. doi:10.1007/bf00266628. PMID 2401635. S2CID 26501940.
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  21. ^ Milius, Susan (1 November 2002). "Bdelloids: No sex for over 40 million years". Science News. Retrieved 6 November 2016.
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  26. ^ Stelzer, Claus-Peter; Schmidt, Johanna; Wiedlroither, Anneliese; Riss, Simone (2010-09-20). "Loss of Sexual Reproduction and Dwarfing in a Small Metazoan". PLOS ONE. 5 (9): e12854. Bibcode:2010PLoSO...512854S. doi:10.1371/journal.pone.0012854. PMC 2942836. PMID 20862222.
  27. ^ Crowe, John H. (1971). "Anhydrobiosis: an unsolved problem". American Naturalist. 105 (946): 563–573. doi:10.1086/282745. JSTOR 2459752. S2CID 84512992.
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  30. ^ Ricci, Claudia; Caprioli, Manuela; Fontaneto, Diego (2007). "Stress and fitness in parthenogens: is dormancy a key feature for bdelloid rotifers?". BMC Evolutionary Biology. 7 (Suppl 2): S9. doi:10.1186/1471-2148-7-S2-S9. PMC 1963474. PMID 17767737.
  31. ^ Wilson, Christopher G.; Sherman, Paul W. (29 January 2010). "Anciently Asexual Bdelloid Rotifers Escape Lethal Fungal Parasites by Drying Up and Blowing Away". Science. 327 (5965): 574–576. Bibcode:2010Sci...327..574W. doi:10.1126/science.1179252. PMID 20110504. S2CID 43898914.
  32. ^ Wilson, Christopher G.; Sherman, Paul W. (22 August 2013). "Spatial and temporal escape from fungal parasitism in natural communities of anciently asexual bdelloid rotifers". Proceedings of the Royal Society B. 280 (1765): 20131255. doi:10.1098/rspb.2013.1255. PMC 3712457. PMID 23825214.
  33. ^ Boschetti, Chiara; Pouchkina-Stantcheva, Natalia; Hoffmann, Pia & Tunnacliffe, Alan (2011). "Foreign genes and novel hydrophilic protein genes participate in the desiccation response of the bdelloid rotifer Adineta ricciae". The Journal of Experimental Biology. 214 (1): 59–68. doi:10.1242/jeb.050328. PMID 21147969.
  34. ^ 60-M-Year-Old Bacteria Shed Light on 'New' DNA Modification System in Animals
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  36. ^ a b Hespeels B, Knapen M, Hanot-Mambres D, Heuskin AC, Pineux F, LUCAS S, Koszul R, Van Doninck K (July 2014). "Gateway to genetic exchange? DNA double-strand breaks in the bdelloid rotifer Adineta vaga submitted to desiccation" (PDF). J. Evol. Biol. 27 (7): 1334–45. doi:10.1111/jeb.12326. PMID 25105197.
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External links Edit

 
Wikimedia Commons has media related to Bdelloidea.
  • Introduction to rotifers
  • Rotifer World Catalog, by Jersabek C.D. & Leitner M.F.
  • The Weird Sisters 2015-10-01 at the Wayback Machine
  • Bdelloids: No sex for over 40 million years 2008-04-23 at the Wayback Machine
  • Who Needs Sex (or Males) Anyway?
  • Tiny Creature Comes Back To Life After 24,000 Years In Siberian Deep Freeze 2021-06-28 at the Wayback Machine

October 15, 2023
bdelloidea, mite, superfamily, mite, ɔɪ, greek, βδέλλα, bdella, leech, class, rotifers, found, freshwater, habitats, over, world, there, over, described, species, bdelloid, rotifers, bdelloids, distinguished, from, each, other, mainly, basis, morphology, main,. For the mite superfamily see Bdelloidea mite Bdelloidea ˈ d ɛ l ɔɪ d i e Greek bdella bdella leech is a class of rotifers found in freshwater habitats all over the world There are over 450 described species of bdelloid rotifers or bdelloids 1 distinguished from each other mainly on the basis of morphology 2 The main characteristics that distinguish bdelloids from related groups of rotifers are exclusively parthenogenetic reproduction and the ability to survive in dry harsh environments by entering a state of desiccation induced dormancy anhydrobiosis at any life stage 3 They are often referred to as ancient asexuals due to their unique asexual history that spans back to over 25 million years ago through fossil evidence 4 Bdelloid rotifers are microscopic organisms typically between 150 and 700 µm in length 3 Most are slightly too small to be seen with the naked eye but appear as tiny white dots through even a weak hand lens especially in bright light In June 2021 biologists reported the restoration of bdelloid rotifers after being frozen for 24 000 years in the Siberian permafrost 5 Bdelloid rotifersTemporal range Miocene present PreꞒ Ꞓ O S D C P T J K Pg NSEM showing morphological variation of bdelloid rotifers and their jawsScientific classificationDomain EukaryotaKingdom AnimaliaPhylum RotiferaSuperclass EurotatoriaClass BdelloideaHudson 1884 Contents 1 Evolutionary relationships 2 Classification and identification 2 1 Morphology 3 Behaviour 3 1 Feeding 3 2 Locomotion 3 3 Reproduction 3 4 Evolution of obligate parthenogenetic reproduction 3 5 Stress induced behaviour 3 6 Horizontal gene transfer 4 Gallery 5 References 6 External linksEvolutionary relationships EditThe phylum Rotifera traditionally included three classes Bdelloidea Monogononta and Seisonidea 6 Prior to 1990 phylogenetic studies based on morphology seemed to indicate that the sister group to bdelloid rotifers was Monogononta with seisonid rotifers as an early diverging outgroup 7 nbsp Cladograms showing alternative possible relationships within Syndermata or Rotifera Transcriptome results published in 2014 8 support a refined version of the scenario in the bottom left with Bdelloidea as a sister group to Seisonidea Acanthocephala and Monogononta as an outgroup Cladograms modified from Fig 3 Lasek Nesselquist 2012 9 Modern molecular phylogenetic studies demonstrate that this classic understanding of Rotifera is incomplete paraphyletic because it omits a fourth clade of closely related organisms the Acanthocephala or thorny headed worms 10 Originally classified as a separate phylum molecular and morphological evidence accumulated between 1994 and 2014 to indicate that Acanthocephala forms a monophyletic group with Bdelloidea Monogononta and Seisonidea 8 11 To accommodate this finding some authors extend the term Rotifera to include the highly modified parasitic acanthocephalan rotifers alongside bdelloid monogonont and seisonid rotifers 12 Others refer to the grouping of the four taxa as Syndermata a term derived from their shared syncytial epidermis 11 The position of Bdelloidea within Syndermata or Rotifera is not entirely clear Alternative possible phylogenetic relationships within the clade are illustrated by the accompanying cladograms As of 2014 the most comprehensive phylogenomic analysis of syndermatan relationships to date was based on transcriptome data from all four groups 8 and provided strong support for the hypothesis illustrated in the bottom left of the figure in which Seisonidea and Acanthocephala are sister taxa The study further indicated that the sister group to this taxon is Bdelloidea whereas Monogononta is the outgroup to all three This would mean that the closest living relatives of bdelloid rotifers are not monogonont rotifers as previously believed but seisonid rotifers and acanthocephalans despite their highly modified morphology Classification and identification EditBdelloidea is a class of the phylum Rotifera consisting of three orders Philodinavida Philodinida and Adinetida 13 These orders are divided into four families and about 450 species 14 Since these organisms are asexual the usual definition of a species as a group of organisms capable of creating fertile offspring is inapplicable therefore the species concept in these organisms is based on a mixture of morphological and molecular data instead DNA studies suggest that the diversity is much greater than the original morphological classifications suggest 15 16 Bdelloids can only be identified by eye while they are alive because many of the characteristics significant to classification are related to feeding and crawling however genetic identification of bdelloids is possible on dead individuals Once preserved the individuals contract into blobs which restricts analysis 17 There are currently three morphological identification methodologies two of which are considered dated Bartos 1951 18 and Donner 1965 14 The third method is a diagnostic key developed in 1995 by Shiel 17 Morphology Edit nbsp Figure 1 SEM pictures of some species of the genus Rotaria with head red tail white and trunk blue areas highlightedThere are three main regions of the body of bdelloids head trunk and foot The adjacent image depicts each area to show how body parts can be very different although they are named the same depending on the species involved Bdelloids typically have a well developed corona divided into two parts on a retractable head Some identifiable features of the bdelloids include Well developed foot glands 17 A mouth opening with a long oesophagus 17 Strong teeth labelled by a tooth index 17 Many cilia 17 Species specific upper lip shape 17 Order specific corona type 3 Philodinida consist of two ciliated discs Adinetida consist of a ventral ciliated field Philodinavida have a small coronaThe bdelloid digestive and reproductive systems can be found within the trunk sections of their bodies with the stomach being the most visible of the organs In certain genera Habrotrocha Otostephanos and Scepanotrocha the bdelloid can actually be identified by the appearance of distinct spherical pellets within the stomach which will be released as faeces These pellets are a distinguishing characteristic since all the other genera release faeces as loose material 3 Most bdelloids retract the foot while they eat but there are four genera that lack a foot Adineta Bradyscela Henoceros and Philodinavus This affects not only how they feed but also how they crawl for instance Adineta and Bradyscela slide whereas the other genera loop 3 Behaviour Edit source source source source source source source A bdelloid feedingThe behaviour of bdelloids can be split into four categories feeding locomotion reproduction and stress induced behaviours Feeding Edit The specific feeding behaviour of bdelloids is varied but most use rings of cilia in the corona organ to create currents of water which blow food through the mouth to the mastax organ which has been adapted specifically for grinding food 19 Food includes suspended bacteria algae detritus and other things Locomotion Edit There appear to be three main methods of movement free swimming inch worming along a substrate or sessility Inch worming or crawling involves taking alternate steps with the head and tail as do certain leeches which gives the group their name Greek bdella or bdella meaning leech This video demonstrates how bdelloids move in three different situations locomotion and feeding of bdelloid rotifers Reproduction Edit Bdelloids are of interest in the study of the evolution of sex because a male has never been observed 20 and females reproduce exclusively by parthenogenesis a form of asexual reproduction where embryos grow and develop without the need for fertilization this is akin to the apomixis seen in some plants 21 Each individual has paired gonads Despite having been asexual for millions of years they have diversified into more than 450 species and are fairly similar to other sexually reproducing rotifer species However a new study provided evidence for interindividual genetic exchange and recombination in Adineta vaga a species previously thought to be anciently asexual 22 Adineta vaga is capable of carrying out DNA repair by a nonreductional meiosis 23 Germline DNA repair occurs in a specific period of oogenesis during which homologous chromosomes take on a meiotic like juxtaposed configuration 23 This germline DNA repair results in accurate reconstitution of the genetic material transmitted to offspring Evolution of obligate parthenogenetic reproduction Edit In 2003 the mode of asexual reproduction in the bdelloid rotifers was wholly unknown 24 One theory of how obligate parthenogenesis arose in bdelloid rotifers was that parthenogenic lineages lost the ability to respond to sex inducing signal which is why these lineages retained their asexuality 25 The obligate parthenogenetic strains of bdelloid rotifers produce a sex inducing signal but have lost the ability to respond to that signal It was later discovered that the inability to respond to sex inducing signals in obligate parthenogens was caused by simple Mendelian inheritance of the gene op 26 Stress induced behaviour Edit Bdelloids are able to survive environmental stresses by entering a state of dormancy known as anhydrobiosis which enables the organism to rapidly dehydrate and thus resist desiccation While preparing for this dormant state many metabolic processes are adjusted to equate for the change in state e g the production of protective chemicals 27 The bdelloid can remain in this state which is known as a xerosome until the return of a sufficient amount of water at which point they will rehydrate and become active within hours Hatching of the young will only occur when conditions are at their most favourable 28 These forms of dormancy are also known as cryptobiosis or quiescence Bdelloids have been known to survive in this state for up to 9 years while waiting for favourable conditions to return 28 In addition to surviving desiccation through anhydrobiosis desiccation stress on two bdelloid species actually helped to maintain fitness and even improved their species fecundity 29 The rotifers that were consistently kept hydrated fared worse than those desiccated and rehydrated 30 Bdelloidea have evolved a unique mechanism to help overcome one of the major perils of asexual reproduction According to the Red Queen hypothesis of co evolution obligate asexuals will be driven extinct by rapidly changing parasites and pathogens because they cannot change their genotypes quickly enough to keep up in this never ending race In populations of bdelloid rotifers however many parasites are destroyed during periods of extended desiccation 31 Moreover desiccated bdelloid rotifers are easily blown away from parasite infested habitats by wind and establish new healthy populations elsewhere which allows them to escape the Red Queen by moving in time and space instead of using sex to change their genotype 32 When these creatures recover from desiccation it has been shown that they undergo a potentially unique genetic process where horizontal gene transfer occurs citation needed resulting in a significant proportion of the bdelloid genome up to 10 having been obtained through horizontal gene transfer from bacteria fungi and plants 33 How and why horizontal gene transfer occur in bdelloids is under much debate at present particularly with regards to possible connections between the foreign genes and the desiccation process as well as possible connections to bdelloids ancient asexuality When they desiccate completely their DNA breaks up into many pieces And when they come back to life after being rehydrated it creates an opportunity for alien DNA fragments to enter their genome This process was improved 60 million years ago when they captured a bacterial gene this way which gave them a new gene regulatory system The new system was used to keep transposons in check 34 Bdelloid rotifers are extraordinarily resistant to damage from ionizing radiation due to the same DNA preserving adaptations used to survive dormancy 35 These adaptations include an extremely efficient mechanism for repairing DNA double strand breaks 36 This repair mechanism was studied in two Bdelloidea species Adineta vaga 36 and Philodina roseola 37 and appears to involve mitotic recombination between homologous DNA regions within each species Horizontal gene transfer Edit Large scale horizontal transfer of bacterial plant and fungal genes into bdelloid rotifers 38 has been documented and may represent an important factor in bdelloid evolution Gallery Edit nbsp Lateral view of a bdelloid nbsp Frontal view of a bdelloid s corona nbsp Lateral view of a bdelloid nbsp Lateral view of a bdelloid nbsp Lateral view of a bdelloid in algae rich water nbsp Specimen of the genus PhilodinaReferences Edit Donner Josef 1965 Ordnung Bdelloidea Rotatoria Radertiere Bestimmungsbucher zur Bodenfauna Europas volume 6 Berlin Akademie Verlag OCLC 6733231 and Segers Hendrik 2007 Annotated checklist of the rotifers Phylum Rotifera with notes on nomenclature taxonomy and distribution Zootaxa 1590 3 104 Abstract Segers Hendrick 2007 Annotated checklist of the rotifers Phylum Rotifera with notes on nomenclature taxonomy and distribution PDF Auckland Magnolia Press ISBN 978 1 86977 129 4 a b c d e Ricci Claudia 2000 Key to the identification of the genera of bdelloid rotifers Hydrobiologia 418 73 80 doi 10 1023 A 1003840216827 S2CID 44054669 Poinar Jr G O Ricci Claudia 1992 Bdelloid rotifers in Dominican amber Evidence for parthenogenetic continuity Experientia 48 4 408 410 doi 10 1007 BF01923444 S2CID 13098228 Renault Marion 7 June 2021 This Tiny Creature Survived 24 000 Years Frozen in Siberian Permafrost The microscopic animals were frozen when woolly mammoths still roamed the planet but were restored as though no time had passed the New York Times Retrieved 7 June 2021 King Charles E Ricci Claudia Schonfeld Justin Serra Manuel September 2005 Evolutionary Dynamics of the Bdelloid and Monogonont Rotifer Life history Patterns Hydrobiologia 546 1 55 70 CiteSeerX 10 1 1 455 6499 doi 10 1007 s10750 005 4102 9 S2CID 25975998 Wallace Robert Lee Colburn Rebecca Arlene December 1989 Phylogenetic relationships within phylum Rotifera orders and genus Notholca Hydrobiologia 186 187 1 311 318 doi 10 1007 BF00048926 S2CID 20809514 a b c Wey Fabrizius Alexandra R Herlyn Holger Rieger Benjamin Rosenkranz David Witek Alexander Welch David B Mark Ebersberger Ingo Hankeln Thomas Schmitz Jurgen 10 February 2014 Transcriptome Data Reveal Syndermatan Relationships and Suggest the Evolution of Endoparasitism in Acanthocephala via an Epizoic Stage PLOS ONE 9 2 e88618 Bibcode 2014PLoSO 988618W doi 10 1371 journal pone 0088618 PMC 3919803 PMID 24520404 Lasek Nesselquist Erica 23 August 2012 A Mitogenomic Re Evaluation of the Bdelloid Phylogeny and Relationships among the Syndermata PLOS ONE 7 8 e43554 Bibcode 2012PLoSO 743554L doi 10 1371 journal pone 0043554 PMC 3426538 PMID 22927990 Welch David B Mark 2001 Early contributions of molecular phylogenetics to understanding the evolution of Rotifera Hydrobiologia 446 315 322 doi 10 1023 A 1017502923286 S2CID 28895228 a b Ahlrichs Wilko H 1997 Epidermal ultrastructure of Seison nebaliae and Seison annulatus and a comparison of epidermal structures within the Gnathifera Zoomorphology 117 1 41 48 doi 10 1007 s004350050028 S2CID 24719056 Nielsen Claus 2012 Animal evolution interrelationships of the living phyla 3rd ed Oxford Oxford University Press ISBN 978 0199606030 Melone Giulio amp Ricci Claudia 1995 Rotatory apparatus in Bdelloids Hydrobiologia 313 1 91 98 doi 10 1007 BF00025935 S2CID 35937088 a b Donner Josef 1965 Ordnung Bdelloidea Akademie Verlag p 297 ISBN 9789031908851 Kaya Murat Herniou Elisabeth A Barraclough Timothy G amp Fontaneto Diego 2009 Inconsistent estimates of diversity between traditional and DNA taxonomy in bdelloid rotifers Organisms Diversity amp Evolution 9 1 3 12 doi 10 1016 j ode 2008 10 002 Fontaneto Diego Kaya Murat Herniou Elisabeth A amp Barraclough Timothy G 2009 Extreme levels of hidden diversity in microscopic animals Rotifera revealed by DNA taxonomy Molecular Phylogenetics and Evolution 53 1 182 189 doi 10 1016 j ympev 2009 04 011 PMID 19398026 a b c d e f g Shiel Russell J 1995 A guide to identification of rotifers cladocerans and copepods from Australian inland waters Australia Co operative Research Centre for Freshwater Ecology ISBN 978 0 646 22410 7 Bartos Emanuel 1951 The Czechoslovak Rotatoria of the order Bdelloidea Memoiresde la Societe Zoologique Tchecoslovaque de Prague 15 241 500 Klusemann J Kleinow W Peters W 1990 The hard parts trophi of the rotifer mastax do contain chitin evidence from studies on Brachionus plicatilis Histochem Cell Biol 94 3 277 283 doi 10 1007 bf00266628 PMID 2401635 S2CID 26501940 Judson Olivia P Normark Benjamin B 1996 Ancient asexual scandals Trends in Ecology amp Evolution 11 2 41 46 doi 10 1016 0169 5347 96 81040 8 PMID 21237759 Milius Susan 1 November 2002 Bdelloids No sex for over 40 million years Science News Retrieved 6 November 2016 Vakhrusheva O A Mnatsakanova E A Galimov Y R 18 December 2020 Genomic signatures of recombination in a natural population of the bdelloid rotifer Adineta vaga Nature 11 1 6421 Bibcode 2020NatCo 11 6421V doi 10 1038 s41467 020 19614 y PMC 7749112 PMID 33339818 a b Terwagne M Nicolas E Hespeels B Herter L Virgo J Demazy C Heuskin A C Hallet B Van Doninck K 2022 DNA repair during nonreductional meiosis in the asexual rotifer Adineta vaga Science Advances 8 48 eadc8829 Bibcode 2022SciA 8C8829T doi 10 1126 sciadv adc8829 PMC 9710870 PMID 36449626 Simon Jean Christophe Delmotte Francois Rispe Claude Crease Teresa 2003 Phylogenetic relationships between parthenogens and their sexual relatives the possible routes to parthenogenesis in animals Biological Journal of the Linnean Society 79 1 151 163 doi 10 1046 j 1095 8312 2003 00175 x Stelzer Claus Peter 2008 Obligate asex in a rotifer and the role of sexual signals Journal of Evolutionary Biology 21 1 287 293 doi 10 1111 j 1420 9101 2007 01437 x PMID 17995949 Stelzer Claus Peter Schmidt Johanna Wiedlroither Anneliese Riss Simone 2010 09 20 Loss of Sexual Reproduction and Dwarfing in a Small Metazoan PLOS ONE 5 9 e12854 Bibcode 2010PLoSO 512854S doi 10 1371 journal pone 0012854 PMC 2942836 PMID 20862222 Crowe John H 1971 Anhydrobiosis an unsolved problem American Naturalist 105 946 563 573 doi 10 1086 282745 JSTOR 2459752 S2CID 84512992 a b Guidetti Roberto amp Jonsson K Ingemar 2002 Long term anhydrobiotic survival in semi terrestrial micrometazoans Journal of Zoology 257 2 181 187 CiteSeerX 10 1 1 630 9839 doi 10 1017 s095283690200078x Ricci Claudia amp Fontaneto Diego 2009 The importance of being a bdelloid ecological and evolutionary consequences of dormancy Italian Journal of Zoology 76 3 240 249 doi 10 1080 11250000902773484 Ricci Claudia Caprioli Manuela Fontaneto Diego 2007 Stress and fitness in parthenogens is dormancy a key feature for bdelloid rotifers BMC Evolutionary Biology 7 Suppl 2 S9 doi 10 1186 1471 2148 7 S2 S9 PMC 1963474 PMID 17767737 Wilson Christopher G Sherman Paul W 29 January 2010 Anciently Asexual Bdelloid Rotifers Escape Lethal Fungal Parasites by Drying Up and Blowing Away Science 327 5965 574 576 Bibcode 2010Sci 327 574W doi 10 1126 science 1179252 PMID 20110504 S2CID 43898914 Wilson Christopher G Sherman Paul W 22 August 2013 Spatial and temporal escape from fungal parasitism in natural communities of anciently asexual bdelloid rotifers Proceedings of the Royal Society B 280 1765 20131255 doi 10 1098 rspb 2013 1255 PMC 3712457 PMID 23825214 Boschetti Chiara Pouchkina Stantcheva Natalia Hoffmann Pia amp Tunnacliffe Alan 2011 Foreign genes and novel hydrophilic protein genes participate in the desiccation response of the bdelloid rotifer Adineta ricciae The Journal of Experimental Biology 214 1 59 68 doi 10 1242 jeb 050328 PMID 21147969 60 M Year Old Bacteria Shed Light on New DNA Modification System in Animals Gladyshev Eugene amp Meselson Matthew 1 April 2008 Extreme resistance of bdelloid rotifers to ionizing radiation Proceedings of the National Academy of Sciences 105 13 5139 5144 Bibcode 2008PNAS 105 5139G doi 10 1073 pnas 0800966105 PMC 2278216 PMID 18362355 a b Hespeels B Knapen M Hanot Mambres D Heuskin AC Pineux F LUCAS S Koszul R Van Doninck K July 2014 Gateway to genetic exchange DNA double strand breaks in the bdelloid rotifer Adineta vaga submitted to desiccation PDF J Evol Biol 27 7 1334 45 doi 10 1111 jeb 12326 PMID 25105197 Welch David B Mark Welch Jessica L Mark amp Meselson Matthew 1 April 2008 Evidence for degenerate tetraploidy in bdelloid rotifers Proceedings of the National Academy of Sciences 105 13 5145 9 Bibcode 2008PNAS 105 5145M doi 10 1073 pnas 0800972105 PMC 2278229 PMID 18362354 Gladyshev Eugene A Meselson Matthew Arkhipova Irina R 2008 05 30 Massive horizontal gene transfer in bdelloid rotifers Science 320 5880 1210 1213 Bibcode 2008Sci 320 1210G doi 10 1126 science 1156407 ISSN 1095 9203 PMID 18511688 S2CID 11862013 External links Edit nbsp Wikimedia Commons has media related to Bdelloidea Introduction to rotifers Rotifer World Catalog by Jersabek C D amp Leitner M F The Weird Sisters Archived 2015 10 01 at the Wayback Machine Bdelloids No sex for over 40 million years Archived 2008 04 23 at the Wayback Machine An Evolutionary Scandal from Harvard Magazine Who Needs Sex or Males Anyway Tiny Creature Comes Back To Life After 24 000 Years In Siberian Deep Freeze Archived 2021 06 28 at the Wayback Machine Retrieved from https en wikipedia org w index php title Bdelloidea amp oldid 1178019103, wikipedia, wiki, book, books, library,

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