Information about Synapomorph
In evolutionary biology, a synapomorphy is a derived character state shared by two or more terminal groups (taxa included in a cladistic analysis as further indivisible units) and inherited from their most recent common ancestor.
"Derived" in this case means that its ancestor again is lacking it — so it is a derived (new) character-state, or apomorphy, originating in their last common ancestor. Consider species A and B, their common ancestor C, and C's ancestor D. If A and B have trait X, and C did as well, but D did not, then X is a synapomorphy: a shared derived (new) character-state, or apomorphy, originating in A and B's last common ancestor, C. True synapomorphies usually uniquely characterise a given set of terminal groups, but this is not essential to the concept. In cladistics, synapomorphies are used to establish phylogenies. As such they are empirical data which can support a certain hypothesis that terminal groups form a clade (monophyletic group) together to the exclusion of certain other groups, whereas character-states that are shared, but also shared by other terminal groups descending from an earlier common ancestor, cannot be used to exclude these other groups. The latter character-states can consist of symplesiomorphies ("primitive" character-states having originated in the earlier common ancestor) or homoplasies (superficially similar but independently evolved derived character-states).
The synapomorphy is thus opposed to both the symplesiomorphy and the homoplasy. Rather uncontroversial examples of the three are:
The concepts of apomorphy and plesiomorphy are relative to a certain level of generality. What counts as an apomorphy at one level of generality may well be a plesiomorphy at the other. E.g., for rats and apes, the presence of five toes on their legs is a symplesiomorphy, but for Tetrapoda in general it might be a synapomorphy.
It is not essential to a synapomorphy that all members of a clade possess it; even if some would have secondarily lost the trait it could still be a synapomorphy of the clade as a whole. A character state that is a synapomorphy for a clade, but for lineages in this clade is a plesiomorphy that is altered in some lineages, is called underlying synapomorphy. If no stem group taxa are known, it is sometimes difficult to decide which character state is the underlying synapomorphy and which the autapomorphy that overlies it.
Clades are not defined by synapomorphies as such, though it is possible to define them by apomorphies in general.
The word synapomorphy is derived from the Greek words σύν, syn = with, in company with, together with, ἀπό, apo = away from and μορφή, morphe = shape.
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"Derived" in this case means that its ancestor again is lacking it — so it is a derived (new) character-state, or apomorphy, originating in their last common ancestor. Consider species A and B, their common ancestor C, and C's ancestor D. If A and B have trait X, and C did as well, but D did not, then X is a synapomorphy: a shared derived (new) character-state, or apomorphy, originating in A and B's last common ancestor, C. True synapomorphies usually uniquely characterise a given set of terminal groups, but this is not essential to the concept. In cladistics, synapomorphies are used to establish phylogenies. As such they are empirical data which can support a certain hypothesis that terminal groups form a clade (monophyletic group) together to the exclusion of certain other groups, whereas character-states that are shared, but also shared by other terminal groups descending from an earlier common ancestor, cannot be used to exclude these other groups. The latter character-states can consist of symplesiomorphies ("primitive" character-states having originated in the earlier common ancestor) or homoplasies (superficially similar but independently evolved derived character-states).
The synapomorphy is thus opposed to both the symplesiomorphy and the homoplasy. Rather uncontroversial examples of the three are:
- Synapomorphy: Halteres, the uniquely modified hind wings, in all families of winged Diptera. No other group of insects possesses similar structures. However, that all winged Diptera would have the trait and no other group would, is not essential to its being a synapomorphy. It only means that it is easier to determine it is one.
- Symplesiomorphy: Five toes on the hind legs in rats and apes. This character-state originated very early in Tetrapoda, occurs in other tetrapod groups, e.g. in lizards, and is thus no indication that the group formed of rats and apes is a clade to the exclusion of these other groups.
- Homoplasy: Homoiothermy in birds and mammals. This trait is a derived character-state (in relation to poikilothermy, the character-state of the last common ancestor of both groups) evolved independently in these two groups (or at least in the larger clades to which these groups belong).
The concepts of apomorphy and plesiomorphy are relative to a certain level of generality. What counts as an apomorphy at one level of generality may well be a plesiomorphy at the other. E.g., for rats and apes, the presence of five toes on their legs is a symplesiomorphy, but for Tetrapoda in general it might be a synapomorphy.
It is not essential to a synapomorphy that all members of a clade possess it; even if some would have secondarily lost the trait it could still be a synapomorphy of the clade as a whole. A character state that is a synapomorphy for a clade, but for lineages in this clade is a plesiomorphy that is altered in some lineages, is called underlying synapomorphy. If no stem group taxa are known, it is sometimes difficult to decide which character state is the underlying synapomorphy and which the autapomorphy that overlies it.
Clades are not defined by synapomorphies as such, though it is possible to define them by apomorphies in general.
The word synapomorphy is derived from the Greek words σύν, syn = with, in company with, together with, ἀπό, apo = away from and μορφή, morphe = shape.
Topics in phylogenetics | |
|---|---|
| Relevant fields | phylogenetics |
| Basic concepts | synapomorphy |
| Phylogeny inference methods | maximum parsimony |
| Current topics | PhyloCode |
| List of evolutionary biology topics | |
Evolutionary biology is a sub-field of biology concerned with the origin and descent of species, as well as their change, multiplication, and diversity over time.
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A taxon (plural taxa), or taxonomic unit, is a name designating an organism or group of organisms. A taxon is assigned a rank and can be placed at a particular level in a systematic hierarchy reflecting evolutionary..... Click the link for more information.
Cladistics is a philosophy of classification that arranges organisms only by their order of branching in an evolutionary tree and not by their morphological similarity, in the words of Luria et al. (1981).
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Cladistics is a philosophy of classification that arranges organisms only by their order of branching in an evolutionary tree and not by their morphological similarity, in the words of Luria et al. (1981).
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Cladistics is a philosophy of classification that arranges organisms only by their order of branching in an evolutionary tree and not by their morphological similarity, in the words of Luria et al. (1981).
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phylogenetics (Greek: phyle = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e.g., species, populations).
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In phylogenetics, a group is monophyletic (Greek: "of one race") if it consists of an inferred common ancestor and all its descendants. A taxonomic group that contains organisms but not their common ancestor is called polyphyletic, and a group that contains some but not all
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A symplesiomorphy or symplesiomorphic character is in cladistics a trait which is shared (a symmorphy) between two or more taxa, but which is also shared with other taxa which have an earlier last common ancestor with the taxa under consideration.
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In evolutionary biology, convergent evolution is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches[1].
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Halteres (IPA pronunciation [hæl'tɪəriːz]; singular halter or haltere), also known as balancers or poisers
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Diptera
Linnaeus, 1758
Suborders
Nematocera (includes Eudiptera)
Brachycera
True flies are insects of the Order Diptera (Greek: di = two, and pteron
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Linnaeus, 1758
Suborders
Nematocera (includes Eudiptera)
Brachycera
True flies are insects of the Order Diptera (Greek: di = two, and pteron
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Insecta
Linnaeus, 1758
Orders
Subclass Apterygota
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Linnaeus, 1758
Orders
Subclass Apterygota
- * Archaeognatha (bristletails)
- * Thysanura (silverfish)
- * Infraclass Paleoptera (Probably paraphyletic)
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Tetrapoda
Broili, 1913
Classes
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Broili, 1913
Classes
- Amphibia
- Aves
- Mammalia
- Sauropsida (Reptilia)
- Synapsida
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Warm-blooded animals maintain thermal homeostasis; that is, they keep their body temperature at a constant level. This involves the ability to cool down or produce more body heat. Warm-blooded animals mainly control their body temperature by regulating their metabolic rates (e.g.
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For the 1995 movie about hitmen, see .
Cold-blooded organisms maintain their body temperatures in ways different from mammals and birds. The term is now outdated in scientific contexts...... Click the link for more information.
In palaeontology, a stem group is a systematic grouping that is required to accommodate fossils in the classification of organisms. A stem group lies basally to a crown group, consisting of its most closely related living relatives.
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Writing system: Greek alphabet
Official status
Official language of: Greece
Cyprus
European Union
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phylogenetics (Greek: phyle = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e.g., species, populations).
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Maximum parsimony, often simply referred to as "parsimony," is a non-parametric statistical method commonly used in computational phylogenetics for estimating phylogenies. Under maximum parsimony, the preferred phylogenetic tree is the tree that requires the least number of
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The International Code of Phylogenetic Nomenclature, known for short as the PhyloCode, is a developing draft for a formal set of rules governing phylogenetic nomenclature.
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This is a list of topics in evolutionary biology and evolution.
See also: List of biology topics, List of biochemistry topics, WikiProject Evolutionary biology
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See also: List of biology topics, List of biochemistry topics, WikiProject Evolutionary biology
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