Body plans have historically been considered to have evolved in a flash in the Ediacaran biota; filling the Cambrian explosion with the results, and a more nuanced understanding of animal evolution suggests gradual development of body plans throughout the early Palaeozoic. Recent studies in animals and plants started to investigate whether evolutionary constraints on body plan structures can explain the presence of developmental constraints during embryogenesis such as the phenomenon referred to as phylotypic stage.
Among the pioneering zoologists, Linnaeus identified two body plans outside the vertebrates; Cuvier identified three; and Haeckel had four, as well as the Protista with eight more, for a total of twelve. For comparison, the number of phyla recognised by modern zoologists has risen to 36.[1]
Haeckel's 'Monophyletischer Stambaum der Organismen' from Generelle Morphologie der Organismen (1866) with the three branches Plantae, Protista, Animalia
In his 1817 work, Le Règne Animal, French zoologist Georges Cuvier combined evidence from comparative anatomy and palaeontology[3] to divide the animal kingdom into four body plans. Taking the central nervous system as the main organ system which controlled all the others, such as the circulatory and digestive systems, Cuvier distinguished four body plans or embranchements:[4]
with a brain and a spinal cord (surrounded by skeletal elements)[4]
Ernst Haeckel, in his 1866 Generelle Morphologie der Organismen, asserted that all living things were monophyletic (had a single evolutionary origin), being divided into plants, protista, and animals. His protista were divided into moneres, protoplasts, flagellates, diatoms, myxomycetes, myxocystodes, rhizopods, and sponges. His animals were divided into groups with distinct body plans: he named these phyla. Haeckel's animal phyla were coelenterates, echinoderms, and (following Cuvier) articulates, molluscs, and vertebrates.[5]
Gould, 1979
Stephen J. Gould explored the idea that the different phyla could be perceived in terms of a Bauplan, illustrating their fixity. However, he later abandoned this idea in favor of punctuated equilibrium.[6]
The current range of body plans is far from exhaustive of the possible patterns for life: the PrecambrianEdiacaran biota includes body plans that differ from any found in currently living organisms, even though the overall arrangement of unrelated modern taxa is quite similar.[10] Thus the Cambrian explosion appears to have more or less completely replaced the earlier range of body plans.[7]
Genes, embryos and development together determine the form of an adult organism's body, through the complex switching processes involved in morphogenesis.
Developmental biologists seek to understand how genes control the development of structural features through a cascade of processes in which key genes produce morphogens, chemicals that diffuse through the body to produce a gradient that acts as a position indicator for cells, turning on other genes, some of which in turn produce other morphogens. A key discovery was the existence of groups of homeobox genes, which function as switches responsible for laying down the basic body plan in animals. The homeobox genes are remarkably conserved between species as diverse as the fruit fly and humans, the basic segmented pattern of the worm or fruit fly being the origin of the segmented spine in humans. The field of animal evolutionary developmental biology ('Evo Devo'), which studies the genetics of morphology in detail, is rapidly expanding[11] with many of the developmental genetic cascades, particularly in the fruit fly Drosophila, catalogued in considerable detail.[12]
^ abValentine, James W. (2004). On the Origin of Phyla. p. 33. ISBN978-0226845487.
^Linnaeus, Carolus (1735). Systema naturae, sive regna tria naturae systematice proposita per classes, ordines, genera, & species. Leiden: Haak. pp. 1–12.
^Reiss, John (2009). Not by Design: Retiring Darwin's Watchmaker. University of California Press. p. 108. ISBN978-0-520-94440-4.
^ abcdeDe Wit, Hendrik Cornelius Dirk De Wit. Histoire du Développement de la Biologie, Volume III, Presses Polytechniques et Universitaires Romandes, Lausanne, 1994, p. 94-96. ISBN2-88074-264-1
^Haeckel, Ernst. Generelle Morphologie der Organismen : allgemeine Grundzüge der organischen Formen-Wissenschaft, mechanisch begründet durch die von Charles Darwin reformirte Descendenz-Theorie. (1866) Berlin
^Bowler, Peter J. (2009). Evolution: the History of an Idea. California, p. 364.
^ abErwin, Douglas; Valentine, James; Jablonski, David (1997). "The origin of animal body plans". American Scientist (March–April).
^Erwin, D. H. (1999). "The Origin of Bodyplans". Integrative and Comparative Biology (American Zoologist). 39 (3): 617–629. doi:10.1093/icb/39.3.617.
^Budd, G. E.; Jensen, S. (2000). "A critical reappraisal of the fossil record of the bilaterian phyla". Biological Reviews of the Cambridge Philosophical Society. 75 (2): 253–95. doi:10.1111/j.1469-185X.1999.tb00046.x. PMID 10881389. S2CID 39772232.
^Antcliffe, J. B.; Brasier, M. D. (2007). "Charnia and sea pens are poles apart". Journal of the Geological Society. 164 (1): 49–51. Bibcode:2007JGSoc.164...49A. doi:10.1144/0016-76492006-080. S2CID 130602154.
^Hall, Brian K. (28 March 2005). "Evo Devo is the New Buzzword..." Scientific American. 292 (4): 102–104. Bibcode:2005SciAm.292d.102H. doi:10.1038/scientificamerican0405-102. Retrieved 13 September 2014.
The Science of Evolution: Sean B. Carroll explains the genetics of the fruit fly body plan.
January 31, 2023
body, plan, body, plan, bauplan, german, baupläne, ground, plan, morphological, features, common, many, members, phylum, animals, vertebrates, share, body, plan, while, invertebrates, have, many, modern, groups, animals, grouped, arrangement, their, body, stru. A body plan Bauplan pl German Bauplane or ground plan is a set of morphological features common to many members of a phylum of animals 1 The vertebrates share one body plan while invertebrates have many Modern groups of animals can be grouped by the arrangement of their body structures so are said to possess different body plans This term usually applied to animals envisages a blueprint encompassing aspects such as symmetry layers segmentation nerve limb and gut disposition Evolutionary developmental biology seeks to explain the origins of diverse body plans Body plans have historically been considered to have evolved in a flash in the Ediacaran biota filling the Cambrian explosion with the results and a more nuanced understanding of animal evolution suggests gradual development of body plans throughout the early Palaeozoic Recent studies in animals and plants started to investigate whether evolutionary constraints on body plan structures can explain the presence of developmental constraints during embryogenesis such as the phenomenon referred to as phylotypic stage Contents 1 History 1 1 Linnaeus 1735 1 2 Cuvier 1817 1 3 Haeckel 1866 1 4 Gould 1979 2 Origin 3 Genetic basis 4 See also 5 References 6 External linksHistory EditAmong the pioneering zoologists Linnaeus identified two body plans outside the vertebrates Cuvier identified three and Haeckel had four as well as the Protista with eight more for a total of twelve For comparison the number of phyla recognised by modern zoologists has risen to 36 1 Linnaeus 1735 Edit In his 1735 book Systema Naturae Swedish botanist Linnaeus grouped the animals into quadrupeds birds amphibians including tortoises lizards and snakes fish insects Insecta in which he included arachnids crustaceans and centipedes and worms Vermes Linnaeus s Vermes included effectively all other groups of animals not only tapeworms earthworms and leeches but molluscs sea urchins and starfish jellyfish squid and cuttlefish 2 Cuvier 1817 Edit Haeckel s Monophyletischer Stambaum der Organismen from Generelle Morphologie der Organismen 1866 with the three branches Plantae Protista Animalia In his 1817 work Le Regne Animal French zoologist Georges Cuvier combined evidence from comparative anatomy and palaeontology 3 to divide the animal kingdom into four body plans Taking the central nervous system as the main organ system which controlled all the others such as the circulatory and digestive systems Cuvier distinguished four body plans or embranchements 4 with a brain and a spinal cord surrounded by skeletal elements 4 with organs linked by nerve fibres 4 with two longitudinal ventral nerve cords linked by a band with two ganglia below the oesophagus 4 with a diffuse nervous system not clearly discernible 4 Grouping animals with these body plans resulted in four branches vertebrates molluscs articulata including insects and annelids and zoophytes or radiata Haeckel 1866 Edit Ernst Haeckel in his 1866 Generelle Morphologie der Organismen asserted that all living things were monophyletic had a single evolutionary origin being divided into plants protista and animals His protista were divided into moneres protoplasts flagellates diatoms myxomycetes myxocystodes rhizopods and sponges His animals were divided into groups with distinct body plans he named these phyla Haeckel s animal phyla were coelenterates echinoderms and following Cuvier articulates molluscs and vertebrates 5 Gould 1979 Edit Stephen J Gould explored the idea that the different phyla could be perceived in terms of a Bauplan illustrating their fixity However he later abandoned this idea in favor of punctuated equilibrium 6 Origin Edit20 out of the 36 body plans originated in the Cambrian period 7 in the Cambrian explosion 8 However complete body plans of many phyla emerged much later in the Palaeozoic or beyond 9 The current range of body plans is far from exhaustive of the possible patterns for life the Precambrian Ediacaran biota includes body plans that differ from any found in currently living organisms even though the overall arrangement of unrelated modern taxa is quite similar 10 Thus the Cambrian explosion appears to have more or less completely replaced the earlier range of body plans 7 Genetic basis EditFurther information evolutionary developmental biology and morphogenesis Genes embryos and development together determine the form of an adult organism s body through the complex switching processes involved in morphogenesis Developmental biologists seek to understand how genes control the development of structural features through a cascade of processes in which key genes produce morphogens chemicals that diffuse through the body to produce a gradient that acts as a position indicator for cells turning on other genes some of which in turn produce other morphogens A key discovery was the existence of groups of homeobox genes which function as switches responsible for laying down the basic body plan in animals The homeobox genes are remarkably conserved between species as diverse as the fruit fly and humans the basic segmented pattern of the worm or fruit fly being the origin of the segmented spine in humans The field of animal evolutionary developmental biology Evo Devo which studies the genetics of morphology in detail is rapidly expanding 11 with many of the developmental genetic cascades particularly in the fruit fly Drosophila catalogued in considerable detail 12 See also Edit Evolutionary biology portal Paleontology portalAnatomical terms of location Standard terms for unambiguous description of relative placement of body parts Arthropod head problem Dispute concerning the evolution of arthropods Deep homology Control of growth and differentiation by deeply conserved genetic mechanisms Evolutionary developmental biology Comparison of organism developmental processes Definition of Phylum based on body plan High level taxonomic rank for organisms sharing a similar body plan Ediacaran biota All organisms of the Ediacaran Period c 635 538 8 million years ago Macroevolution Evolution on a scale at or above the level of species Precambrian body plans Structure and development of early multicellular organisms Sean B Carroll American evolutionary developmental biologist Segmentation biology Division of some animal and plant body plans into a series of segments Supernumerary body part Growth of an additional part of the body and a deviation from the body plan Symmetry in biology Geometric symmetry in living beingsReferences Edit a b Valentine James W 2004 On the Origin of Phyla p 33 ISBN 978 0226845487 Linnaeus Carolus 1735 Systema naturae sive regna tria naturae systematice proposita per classes ordines genera amp species Leiden Haak pp 1 12 Reiss John 2009 Not by Design Retiring Darwin s Watchmaker University of California Press p 108 ISBN 978 0 520 94440 4 a b c d e De Wit Hendrik Cornelius Dirk De Wit Histoire du Developpement de la Biologie Volume III Presses Polytechniques et Universitaires Romandes Lausanne 1994 p 94 96 ISBN 2 88074 264 1 Haeckel Ernst Generelle Morphologie der Organismen allgemeine Grundzuge der organischen Formen Wissenschaft mechanisch begrundet durch die von Charles Darwin reformirte Descendenz Theorie 1866 Berlin Bowler Peter J 2009 Evolution the History of an Idea California p 364 a b Erwin Douglas Valentine James Jablonski David 1997 The origin of animal body plans American Scientist March April Erwin D H 1999 The Origin of Bodyplans Integrative and Comparative Biology American Zoologist 39 3 617 629 doi 10 1093 icb 39 3 617 Budd G E Jensen S 2000 A critical reappraisal of the fossil record of the bilaterian phyla Biological Reviews of the Cambridge Philosophical Society 75 2 253 95 doi 10 1111 j 1469 185X 1999 tb00046 x PMID 10881389 S2CID 39772232 Antcliffe J B Brasier M D 2007 Charnia and sea pens are poles apart Journal of the Geological Society 164 1 49 51 Bibcode 2007JGSoc 164 49A doi 10 1144 0016 76492006 080 S2CID 130602154 Hall Brian K 28 March 2005 Evo Devo is the New Buzzword Scientific American 292 4 102 104 Bibcode 2005SciAm 292d 102H doi 10 1038 scientificamerican0405 102 Retrieved 13 September 2014 Arthur Wallace 1997 Animal Body Plans Cambridge England Cambridge University Press ISBN 0 521 77928 6 External links EditDevelopmental Biology 8e Online Patterning of the Mesoderm by ActivinVideosThe Science of Evolution Sean B Carroll explains the genetics of the fruit fly body plan Retrieved from https en wikipedia org w index php title Body plan amp oldid 1125644563, wikipedia, wiki, book, books, library,
