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Igamberdiev AU, Gordon R. Macroevolution, differentiation trees, and the growth of coding systems. Biosystems 2023; 234:105044. [PMID: 37783374 DOI: 10.1016/j.biosystems.2023.105044] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/04/2023]
Abstract
An open process of evolution of multicellular organisms is based on the rearrangement and growth of the program of differentiation that underlies biological morphogenesis. The maintenance of the final (adult) stable non-equilibrium state (stasis) of a developmental system determines the direction of the evolutionary process. This state is achieved via the sequence of differentiation events representable as differentiation trees. A special type of morphogenetic code, acting as a metacode governing gene expression, may include electromechanical signals appearing as differentiation waves. The excessive energy due to the incorporation of mitochondria in eukaryotic cells resulted not only in more active metabolism but also in establishing the differentiation code for interconnecting cells and forming tissues, which fueled the evolutionary process. The "invention" of "continuing differentiation" distinguishes multicellular eukaryotes from other organisms. The Janus-faced control, involving both top-down control by differentiation waves and bottom-up control via the mechanical consequences of cell differentiations, underlies the process of morphogenesis and results in the achievement of functional stable final states. Duplications of branches of the differentiation tree may be the basis for continuing differentiation and macroevolution, analogous to gene duplication permitting divergence of genes. Metamorphoses, if they are proven to be fusions of disparate species, may be classified according to the topology of fusions of two differentiation trees. In the process of unfolding of morphogenetic structures, microevolution can be defined as changes of the differentiation tree that preserve topology of the tree, while macroevolution represents any change that alters the topology of the differentiation tree.
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Affiliation(s)
- Abir U Igamberdiev
- Department of Biology, Memorial University of Newfoundland, St. John's, NL, Canada.
| | - Richard Gordon
- Gulf Specimen Marine Laboratory & Aquarium, 222 Clark Drive, Panacea, FL, 32346, USA.
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Schierwater B, Osigus HJ, Bergmann T, Blackstone NW, Hadrys H, Hauslage J, Humbert PO, Kamm K, Kvansakul M, Wysocki K, DeSalle R. The enigmatic Placozoa part 1: Exploring evolutionary controversies and poor ecological knowledge. Bioessays 2021; 43:e2100080. [PMID: 34472126 DOI: 10.1002/bies.202100080] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 07/21/2021] [Accepted: 08/16/2021] [Indexed: 12/13/2022]
Abstract
The placozoan Trichoplax adhaerens is a tiny hairy plate and more simply organized than any other living metazoan. After its original description by F.E. Schulze in 1883, it attracted attention as a potential model for the ancestral state of metazoan organization, the "Urmetazoon". Trichoplax lacks any kind of symmetry, organs, nerve cells, muscle cells, basal lamina, and extracellular matrix. Furthermore, the placozoan genome is the smallest (not secondarily reduced) genome of all metazoan genomes. It harbors a remarkably rich diversity of genes and has been considered the best living surrogate for a metazoan ancestor genome. The phylum Placozoa presently harbors three formally described species, while several dozen "cryptic" species are yet awaiting their description. The phylogenetic position of placozoans has recently become a contested arena for modern phylogenetic analyses and view-driven claims. Trichoplax offers unique prospects for understanding the minimal requirements of metazoan animal organization and their corresponding malfunctions.
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Affiliation(s)
- Bernd Schierwater
- Institute of Animal Ecology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Hans-Jürgen Osigus
- Institute of Animal Ecology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Tjard Bergmann
- Institute of Animal Ecology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Neil W Blackstone
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, USA
| | - Heike Hadrys
- Institute of Animal Ecology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Jens Hauslage
- Gravitational Biology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Patrick O Humbert
- Department of Biochemistry & Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia.,Research Centre for Molecular Cancer Prevention, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Kai Kamm
- Institute of Animal Ecology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Marc Kvansakul
- Department of Biochemistry & Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia.,Research Centre for Molecular Cancer Prevention, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Kathrin Wysocki
- Institute of Animal Ecology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Rob DeSalle
- American Museum of Natural History, New York, New York, USA
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