Synapomorphy and apomorphy

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Phylogenies showing the terminology used to describe different patterns of ancestral and derived character or trait states. Synapomorphy.jpg
Phylogenies showing the terminology used to describe different patterns of ancestral and derived character or trait states.

In phylogenetics, apomorphy and synapomorphy [2] refer to derived characters of a clade: characters or traits that are derived from ancestral characters over evolutionary history. [3] An apomorphy is a character that is different from the form found in an ancestor, i.e., an innovation, that sets the clade apart from other clades. A synapomorphy is a shared apomorphy that distinguishes a clade from other organisms. [1] [4] In other words, it is an apomorphy shared by members of a monophyletic group, and thus assumed to be present in their most recent common ancestor.

Contents

Description

An apomorphy is a character that is different from the form found in an ancestor, i.e., an innovation, that sets the clade apart ("apo–") from other clades. A synapomorphy is a shared ("syn") apomorphy that distinguishes a clade from other organisms. [1] [4] In other words, it is an apomorphy shared by members of a monophyletic group, and thus assumed to be present in their most recent common ancestor.

Example

In most groups of mammals, the vertebral column is highly conserved, with the same number of vertebrae found in the neck of a giraffe, for example, as in mammals with shorter necks. However, in the Afrotheria clade, which includes elephant shrews, golden moles and elephants, there is an increase in the number of thoracolumbar vertebrae. This is a synapomorphy of the clade: a shared feature considered to be derived from a common ancestor. [5]

Etymology

The word synapomorphy—coined by German entomologist Willi Hennig—is derived from the Greek words σύν, syn = shared; ἀπό, apo = away from; and μορφή, morphe = shape.

Phylogenetic similarities

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 synapomorphies. [6] [7]

Analysis

The concept of synapomorphy is relative to a given clade in the tree of life. 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.

Cladogram comprehension

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. [21]

Related Research Articles

Cladistics Method of biological systematics in evolutionary biology

Cladistics is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived characteristics (synapomorphies) that are not present in more distant groups and ancestors. Theoretically, a common ancestor and all its descendants are part of the clade, however, from an empirical perspective, common ancestors are inferences based on a cladistic hypothesis of relationships of taxa whose character states can be observed. Importantly, all descendants stay in their overarching ancestral clade. For example, if within a strict cladistic framework the terms worms or fishes were used, these terms would include humans. Many of these terms are normally used paraphyletically, outside of cladistics, e.g. as a 'grade'. Radiation results in the generation of new subclades by bifurcation, but in practice sexual hybridization may blur very closely related groupings.

Monophyly Property of a group of including all taxa descendant from a common ancestral species

In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor and all of its lineal descendants. Monophyletic groups are typically characterised by shared derived characteristics (synapomorphies), which distinguish organisms in the clade from other organisms. An equivalent term is holophyly.

Phylogenetics Study of evolutionary relationships between organisms

In biology, phylogenetics is a part of systematics that addresses the inference of the evolutionary history and relationships among or within groups of organisms. These relationships are hypothesized by phylogenetic inference methods that evaluate observed heritable traits, such as DNA sequences, protein amino acid sequences, or morphology, often under a specified model of evolution of these traits. The result of such an analysis is a phylogeny —a diagrammatic hypothesis of relationships that reflects the evolutionary history of a group of organisms. The tips of a phylogenetic tree can be living taxa or fossils, and represent the 'end', or the present, in an evolutionary lineage. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor, or ancestral lineage, of the tree. An unrooted tree diagram makes no assumption about the ancestral line, and does not show the origin or "root" of the taxa in question or the direction of inferred evolutionary transformations. In addition to their proper use for inferring phylogenetic patterns among taxa, phylogenetic analyses are often employed to represent relationships among gene copies or individual organisms. Such uses have become central to understanding biodiversity, evolution, ecology, and genomes. In February 2021, scientists reported, for the first time, the sequencing of DNA from animal remains, a mammoth in this instance, over a million years old, the oldest DNA sequenced to date.

In biology, phenetics, also known as taximetrics, is an attempt to classify organisms based on overall similarity, usually in morphology or other observable traits, regardless of their phylogeny or evolutionary relation. It is closely related to numerical taxonomy which is concerned with the use of numerical methods for taxonomic classification. Many people contributed to the development of phenetics, but the most influential were Peter Sneath and Robert R. Sokal. Their books are still primary references for this sub-discipline, although now out of print.

Paraphyly Property of a group which includes only descendants of a common ancestor, but excludes at least one monophyletic subgroup

In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and all descendants of that ancestor excluding a few—typically only one or two—monophyletic subgroups. The group is said to be paraphyletic with respect to the excluded subgroups. A paraphyletic group cannot be a clade, or monophyletic group, which is any group of species that includes a common ancestor and all of its descendants. One or more members of a paraphyletic group is more closely related to the excluded group(s) than it is to other members of the paraphyletic group. The term is commonly used in phylogenetics and in linguistics. Paraphyletic groups are identified by a combination of synapomorphies and symplesiomorphies.

Cladogram Diagram used to show relations among groups of organisms with common origins

A cladogram is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to descendants, nor does it show how much they have changed, so many differing evolutionary trees can be consistent with the same cladogram. A cladogram uses lines that branch off in different directions ending at a clade, a group of organisms with a last common ancestor. There are many shapes of cladograms but they all have lines that branch off from other lines. The lines can be traced back to where they branch off. These branching off points represent a hypothetical ancestor which can be inferred to exhibit the traits shared among the terminal taxa above it. This hypothetical ancestor might then provide clues about the order of evolution of various features, adaptation, and other evolutionary narratives about ancestors. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational phylogenetics are now very commonly used in the generation of cladograms, either on their own or in combination with morphology.

Homology (biology) Shared ancestry between a pair of structures or genes in different taxa

In biology, homology is similarity due to shared ancestry between a pair of structures or genes in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of primates, the front flippers of whales and the forelegs of four-legged vertebrates like dogs and crocodiles are all derived from the same ancestral tetrapod structure. Evolutionary biology explains homologous structures adapted to different purposes as the result of descent with modification from a common ancestor. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this, from Aristotle onwards, and it was explicitly analysed by Pierre Belon in 1555.

Polyphyly Set of organisms that do not share an immediate common ancestor

A polyphyletic group or assemblage is a set of organisms, or other evolving elements, that have been grouped together based on characteristics that do not imply that they share a common ancestor that is not also the common ancestor of many other taxa. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of convergent evolution. The arrangement of the members of a polyphyletic group is called a polyphyly.

Evolutionary taxonomy, evolutionary systematics or Darwinian classification is a branch of biological classification that seeks to classify organisms using a combination of phylogenetic relationship, progenitor-descendant relationship, and degree of evolutionary change. This type of taxonomy may consider whole taxa rather than single species, so that groups of species can be inferred as giving rise to new groups. The concept found its most well-known form in the modern evolutionary synthesis of the early 1940s.

Outgroup (cladistics)

In cladistics or phylogenetics, an outgroup is a more distantly related group of organisms that serves as a reference group when determining the evolutionary relationships of the ingroup, the set of organisms under study, and is distinct from sociological outgroups. The outgroup is used as a point of comparison for the ingroup and specifically allows for the phylogeny to be rooted. Because the polarity (direction) of character change can be determined only on a rooted phylogeny, the choice of outgroup is essential for understanding the evolution of traits along a phylogeny.

In phylogenetics, maximum parsimony is an optimality criterion under which the phylogenetic tree that minimizes the total number of character-state changes is to be preferred. Under the maximum-parsimony criterion, the optimal tree will minimize the amount of homoplasy. In other words, under this criterion, the shortest possible tree that explains the data is considered best. Some of the basic ideas behind maximum parsimony were presented by James S. Farris in 1970 and Walter M. Fitch in 1971.

In phylogenetics, long branch attraction (LBA) is a form of systematic error whereby distantly related lineages are incorrectly inferred to be closely related. LBA arises when the amount of molecular or morphological change accumulated within a lineage is sufficient to cause that lineage to appear similar to another long-branched lineage, solely because they have both undergone a large amount of change, rather than because they are related by descent. Such bias is more common when the overall divergence of some taxa results in long branches within a phylogeny. Long branches are often attracted to the base of a phylogenetic tree, because the lineage included to represent an outgroup is often also long-branched. The frequency of true LBA is unclear and often debated, and some authors view it as untestable and therefore irrelevant to empirical phylogenetic inference. Although often viewed as a failing of parsimony-based methodology, LBA could in principle result from a variety of scenarios and be inferred under multiple analytical paradigms.

In phylogenetics, a primitive character, trait, or feature of a lineage or taxon is one that is inherited from the common ancestor of a clade and has undergone little change since. Conversely, a trait that appears within the clade group is called advanced or derived. A clade is a group of organisms that consists of a common ancestor and all its lineal descendants.

Plesiomorphy and symplesiomorphy Ancestral character or trait state shared by two or more taxa

In phylogenetics, a plesiomorphy is an ancestral character state. A symplesiomorphy is a plesiomorphy shared by two or more taxa. Pseudoplesiomorphy is any trait that can neither be identified as a plesiomorphy nor as an apomorphy.

Autapomorphy Distinctive feature, known as a derived trait, that is unique to a given taxon

In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to the focal taxon. It can therefore be considered an apomorphy in relation to a single taxon. The word autapomorphy, first introduced in 1950 by German entomologist Willi Hennig, is derived from the Greek words αὐτός, aut- = "self"; ἀπό, apo = "away from"; and μορφή, morphḗ = "shape".

Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a type, which can be a specimen or a taxon of lower rank, and a description in words. Phylogenetic nomenclature is currently regulated by the International Code of Phylogenetic Nomenclature (PhyloCode).

Outline of evolution Hierarchical outline list of articles related to evolution

The following outline is provided as an overview of and topical guide to evolution:

Character evolution

Character evolution is the process by which a character or trait evolves along the branches of an evolutionary tree. Character evolution usually refers to single changes within a lineage that make this lineage unique from others. These changes are called character state changes and they are often used in the study of evolution to provide a record of common ancestry. Character state changes can be phenotypic changes, nucleotide substitutions, or amino acid substitutions. These small changes in a species can be identifying features of when exactly a new lineage diverged from an old one.

Homoplasy

Homoplasy, in biology and phylogenetics, is when a trait has been gained or lost independently in separate lineages over the course of evolution. This is different from homology, which is when the similarity of traits can be parsimoniously explained by common ancestry. Homoplasy can arise from both similar selection pressures acting on adapting species, and the effects of genetic drift.

This glossary of evolutionary biology is a list of definitions of terms and concepts used in the study of evolutionary biology, population biology, speciation, and phylogenetics, as well as sub-disciplines and related fields. For additional terms from related glossaries, see Glossary of genetics, Glossary of ecology, and Glossary of biology.

References

  1. 1 2 3 Roderick D.M. Page; Edward C. Holmes (14 July 2009). Molecular Evolution: A Phylogenetic Approach. John Wiley & Sons. ISBN   978-1-4443-1336-9.
  2. ↑ Currie PJ, Padia K (1997). Encyclopedia of Dinosaurs. Elsevier. p. 543. ISBN   978-0-08-049474-6.
  3. ↑ Concise Encyclopedia Biology . Tubingen, DEU: Walter de Gruyter. 1996. p.  366. ISBN   9783110106619.
  4. 1 2 Barton N, Briggs D, Eisen J, Goldstein D, Patel N (2007). "Phylogenetic Reconstruction". Evolution. Cold Spring Harbor Laboratory Press.
  5. ↑ Sánchez‐Villagra, Marcelo R.; Narita, Yuichi; Kuratani, Shigeru (2007-03-01). "Thoracolumbar vertebral number: The first skeletal synapomorphy for afrotherian mammals". Systematics and Biodiversity. 5 (1): 1–7. doi:10.1017/s1477200006002258. ISSN   1477-2000. S2CID   85675984.
  6. ↑ Roderick D.M. Page; Edward C. Holmes (14 July 2009).  Molecular Evolution: A Phylogenetic Approach. John Wiley & Sons.  ISBN   978-1-4443-1336-9.
  7. ↑ Calow PP (2009). Encyclopedia of Ecology and Environmental Management. John Wiley & Sons. ISBN   978-1-4443-1324-6. OCLC   1039167559.
  8. ↑ Williams D, Schmitt M, Wheeler Q (July 2016). The Future of Phylogenetic Systematics: The Legacy of Willi Hennig. Cambridge University Press. ISBN   978-1-107-11764-8.
  9. ↑ Simpson MG (9 August 2011). Plant Systematics. Elsevier. Amsterdam: Elsevier. ISBN   9780080514048.
  10. ↑ Russell PJ, Hertz PE, McMillan B (2013). Biology: The Dynamic Science. Cengage Learning. ISBN   978-1-285-41534-5.
  11. ↑ Lipscomb D (1998). "Basics of Cladistic Analysis" (PDF). Washington D.C.: George Washington University.
  12. ↑ Choudhuri S (2014-05-09). Bioinformatics for Beginners: Genes, Genomes, Molecular Evolution, Databases and Analytical Tools (1st ed.). Academic Press. p. 51. ISBN   978-0-12-410471-6. OCLC   950546876.
  13. ↑ 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.
  14. ↑ Gauger A (April 17, 2012). "Similarity Happens! The Problem of Homoplasy". Evolution Today & Science News.
  15. ↑ Sanderson MJ, Hufford L (21 October 1996). Homoplasy: The Recurrence of Similarity in Evolution. Elsevier. ISBN   978-0-08-053411-4. OCLC   173520205.
  16. ↑ Brandley MC, Warren DL, Leaché AD, McGuire JA (April 2009). "Homoplasy and clade support". Systematic Biology. 58 (2): 184–98. doi: 10.1093/sysbio/syp019 . PMID   20525577.
  17. ↑ Archie JW (September 1989). "Homoplasy Excess Ratios: New Indices for Measuring Levels of Homoplasy in Phylogenetic Systematics and a Critique of the Consistency Index". Systematic Biology. 38 (1): 253–269. doi:10.2307/2992286. JSTOR   2992286.
  18. ↑ Wake DB, Wake MH, Specht CD (February 2011). "Homoplasy: from detecting pattern to determining process and mechanism of evolution". Science. 331 (6020): 1032–5. Bibcode:2011Sci...331.1032W. doi:10.1126/science.1188545. PMID   21350170. S2CID   26845473. Lay summary –Science Daily.
  19. ↑ Avise JC, Robinson TJ (June 2008). "Hemiplasy: a new term in the lexicon of phylogenetics". Systematic Biology. 57 (3): 503–7. doi: 10.1080/10635150802164587 . PMID   18570042.
  20. ↑ 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 (November 2017). "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. doi: 10.1073/pnas.1706367114 . PMC   5692538 . PMID   29078296.
  21. ↑ Novick LR, Catley KM. Understanding phylogenies in biology: the influence of a Gestalt perceptual principle. J Exp Psychol Appl. 2007;13:197–223.
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