Apomorphy and synapomorphy explained

In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy).^{[1] [2] [3]} A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have evolved in their most recent common ancestor.^{[4] [5] [6] [7] [8] [9]} In cladistics, synapomorphy implies homology.^[4]

Examples of apomorphy are the presence of erect gait, fur, the evolution of three middle ear bones, and mammary glands in mammals but not in other vertebrate animals such as amphibians or reptiles, which have retained their ancestral traits of a sprawling gait and lack of fur.^[10] Thus, these derived traits are also synapomorphies of mammals in general as they are not shared by other vertebrate animals.^[10]

Etymology

The word —coined by German entomologist Willi Hennig—is derived from the Ancient Greek words (sún), meaning "with, together"; (apó), meaning "away from"; and (morphḗ), meaning "shape, form".

Examples

Lampreys and sharks share some features, like a nervous system, that are not synapomorphic because they are also shared by invertebrates. In contrast, the presence of jaws and paired appendages^[11] in both sharks and dogs, but not in lampreys or close invertebrate relatives, identifies these traits as synapomorphies. This supports the hypothesis that dogs and sharks are more closely related to each other than to lampreys.

Clade analysis

The concept of synapomorphy depends on a given clade in the tree of life. Cladograms are diagrams that depict evolutionary relationships within groups of taxa. These illustrations are accurate predictive device in modern genetics. They are usually depicted in either tree or ladder form. Synapomorphies then create evidence for historical relationships and their associated hierarchical structure. Evolutionarily, a synapomorphy is the marker for the most recent common ancestor of the monophyletic group consisting of a set of taxa in a cladogram.^[12] What counts as a synapomorphy for one clade may well be a primitive character or plesiomorphy at a less inclusive or nested clade. For example, the presence of mammary glands is a synapomorphy for mammals in relation to tetrapods but is a symplesiomorphy for mammals in relation to one another—rodents and primates, for example. So the concept can be understood as well in terms of "a character newer than" (autapomorphy) and "a character older than" (plesiomorphy) the apomorphy: mammary glands are evolutionarily newer than vertebral column, so mammary glands are an autapomorphy if vertebral column is an apomorphy, but if mammary glands are the apomorphy being considered then vertebral column is a plesiomorphy.

Relations to other terms

These phylogenetic terms are used to describe different patterns of ancestral and derived character or trait states as stated in the above diagram in association with apomorphies and synapomorphies.^{[13] [14]}

• Symplesiomorphy – an ancestral trait shared by two or more taxa.
  • Plesiomorphy – a symplesiomorphy discussed in reference to a more derived state.
  • Pseudoplesiomorphy – is a trait that cannot be identified as neither a plesiomorphy nor an apomorphy that is a reversal.^[15]
• Reversal – is a loss of derived trait present in ancestor and the reestablishment of a plesiomorphic trait.
• Convergence – independent evolution of a similar trait in two or more taxa.
• Apomorphy – a derived trait. Apomorphy shared by two or more taxa and inherited from a common ancestor is synapomorphy. Apomorphy unique to a given taxon is autapomorphy.^{[16] [17] [18] [19]}
  • Synapomorphy/homology – a derived trait that is found in some or all terminal groups of a clade, and inherited from a common ancestor, for which it was an autapomorphy (i.e., not present in its immediate ancestor).
  • Underlying synapomorphy – a synapomorphy that has been lost again in many members of the clade. If lost in all but one, it can be hard to distinguish from an autapomorphy.
  • Autapomorphy – a distinctive derived trait that is unique to a given taxon or group.^[20]
• Homoplasy in biological systematics is when a trait has been gained or lost independently in separate lineages during evolution. This convergent evolution leads to species independently sharing a trait that is different from the trait inferred to have been present in their common ancestor.^{[21] [22] [23]}
  • Parallel homoplasy – derived trait present in two groups or species without a common ancestor due to convergent evolution.^[24]
  • Reverse homoplasy – trait present in an ancestor but not in direct descendants that reappears in later descendants.^[25]
• Hemiplasy is the case where a character that appears homoplastic given the species tree actually has a single origin on the associated gene tree.^{[26] [27]} Hemiplasy reflects gene tree-species tree discordance due to the multispecies coalescent.

External links

• Cladistics, Berkeley

Notes and References

1. Book: Futuyma . Douglas J. . Kirkpatrick . Mark . 2017. 27–53 . Tree of life . Evolution . 4th . Sinauer Associates . Sunderland, Mass..
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3. Web site: Reconstructing trees: Cladistics . Understanding Evolution . 5 May 2021 . University of California Museum of Paleontology . 16 October 2021 .
4. Encyclopedia: Kitching . Ian J. . Forey . Peter L. . Williams . David M. . Levin . Simon A. . Cladistics . Encyclopedia of Biodiversity . 2001 . 2nd . 33–45 . Elsevier . 10.1016/B978-0-12-384719-5.00022-8 . 9780123847201 . 29 August 2021 .)
5. Book: Futuyma . Douglas J. . Kirkpatrick . Mark . 2017. 401–429 . Phylogeny: The unity and diversity of life . Evolution . 4th . Sinauer Associates . Sunderland, Mass..
6. Book: Hillis . David M. . Sadava . David . Hill . Richard W. . Price . Mary V. . Reconstructing and using phylogenies . Principles of Life . Sinauer Associates . 2nd . 2014 . Sunderland, Mass. . 325–342 . 978-1464175121.
7. Book: Philip J. . Currie . Kevin . Padia . vanc . Encyclopedia of Dinosaurs . 543 . 978-0-08-049474-6 . Elsevier . 1997 .
8. Book: Concise Encyclopedia Biology . registration . 1996 . Walter de Gruyter . Tubingen, DEU . 366 . 9783110106619 .
9. Book: Barton . Nicholas . Briggs . Derek . Eisen . Jonathan . Goldstein . David. Patel . Nipam . vanc . Evolution . 2007 . Cold Spring Harbor Laboratory Press . http://www.evolution-textbook.org/content/free/contents/ch27.html . Phylogenetic Reconstruction.
10. Baum . David . 2008 . Trait Evolution on a Phylogenetic Tree: Relatedness, Similarity, and the Myth of Evolutionary Advancement . Nature Education . 1 . 1 . 191 .
11. Web site: andrewgillis . 2016-04-19 . Gills, fins and the evolution of vertebrate paired appendages . 2024-06-09 . the Node . en.
12. Novick LR, Catley KM. Understanding phylogenies in biology: the influence of a Gestalt perceptual principle. J Exp Psychol Appl. 2007;13:197–223.
13. Roderick D.M. Page; Edward C. Holmes (14 July 2009). Molecular Evolution: A Phylogenetic Approach. John Wiley & Sons. .
14. Book: Calow . Peter P. . vanc . Encyclopedia of Ecology and Environmental Management . 2009 . John Wiley & Sons . 978-1-4443-1324-6 . 1039167559 .
15. Book: David . Williams . Michael . Schmitt . Quentin . Wheeler . vanc . The Future of Phylogenetic Systematics: The Legacy of Willi Hennig . Cambridge University Press . July 2016 . 978-1-107-11764-8 .
16. Book: Simpson, Michael G. . Plant Systematics . vanc . Amsterdam . Elsevier . 9 August 2011 . 9780080514048 .
17. Book: Peter J. . Russell . Paul E. . Hertz . Beverly . McMillan . vanc . Biology: The Dynamic Science . 978-1-285-41534-5 . Cengage Learning . 2013 .
18. Web site: Basics of Cladistic Analysis . Diana . Lipscomb . vanc . George Washington University . Washington D.C. . 1998.
19. Book: Choudhuri, Supratim . vanc . Bioinformatics for Beginners: Genes, Genomes, Molecular Evolution, Databases and Analytical Tools . 1st . Academic Press . 978-0-12-410471-6 . 950546876 . 51 . 2014-05-09 .
20. Appel, Ron D.; Feytmans, Ernest. Bioinformatics: a Swiss Perspective."Chapter 3: Introduction of Phylogenetics and its Molecular Aspects." World Scientific Publishing Company, 1st edition. 2009.
21. Web site: Similarity Happens! The Problem of Homoplasy . Ann . Gauger . vanc . April 17, 2012 . Evolution Today & Science News .
22. Book: Michael J. . Sanderson . Larry . Hufford . vanc . Homoplasy: The Recurrence of Similarity in Evolution . Elsevier . 21 October 1996 . 978-0-08-053411-4 . 173520205 .
23. Brandley MC, Warren DL, Leaché AD, McGuire JA . Homoplasy and clade support . Systematic Biology . 58 . 2 . 184–98 . April 2009 . 20525577 . 10.1093/sysbio/syp019 . free .
24. James W. . Archie . vanc . Homoplasy Excess Ratios: New Indices for Measuring Levels of Homoplasy in Phylogenetic Systematics and a Critique of the Consistency Index . Systematic Biology . 38 . 1 . September 1989 . 253–269 . 10.2307/2992286 . 2992286 .
25. Wake DB, Wake MH, Specht CD . Homoplasy: from detecting pattern to determining process and mechanism of evolution . Science . 331 . 6020 . 1032–5 . February 2011 . 21350170 . 10.1126/science.1188545 . 2011Sci...331.1032W . 26845473.
    • February 25, 2011 . Homoplasy: A good thread to pull to understand the evolutionary ball of yarn . ScienceDaily .
26. Avise JC, Robinson TJ . Hemiplasy: a new term in the lexicon of phylogenetics . Systematic Biology . 57 . 3 . 503–7 . June 2008 . 18570042 . 10.1080/10635150802164587 . free .
27. Copetti D, Búrquez A, Bustamante E, Charboneau JL, Childs KL, Eguiarte LE, Lee S, Liu TL, McMahon MM, Whiteman NK, Wing RA, Wojciechowski MF, Sanderson MJ . Extensive gene tree discordance and hemiplasy shaped the genomes of North American columnar cacti . Proceedings of the National Academy of Sciences of the United States of America . 114 . 45 . 12003–12008 . November 2017 . 29078296 . 5692538 . 10.1073/pnas.1706367114 . 2017PNAS..11412003C . free .