polytomy


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polytomy

(pə-lĭt′ə-mē)
n.
In a cladogram, a point from which two or more new branches diverge, representing either of two cases:
a. A multiple speciation event in which two or more species diverge from the same ancestor. Also called hard polytomy.
b. A speciation event in which two or more species are presumed to descend from the same ancestor, but the order of speciation is unknown. Also called soft polytomy.
References in periodicals archive ?
Phylogenetically, Novumbra is either sister to Esox (Lopez and others 2004) or in a polytomy with Esox and Umbra (Grande and others 2004).
Microtus maximowiczii clades I and II are placed in an unresolved polytomy in the cytb tree with M.
(2009a), Cladium is the first branch to diverge, but Sclerieae + Bisboeckelereae form a polytomy with the remainder of Cyperoideae; in Jung and Choi (2012), both clades form a polytomy with the remainder of the Cyperoideae (cf.
The resulting consensus tree obtained after removing the 13 unstable OTUs shows an unresolved Pliosaurus polytomy and a partially resolved monophyletic Brachaucheninae clade (Figure 8B).
Those authors found the Jacob's Well specimens to fall within a large Eurycea complex polytomy that includes salamanders from sites recognized to have E.
galloprovincialis-SH clustered into a large polytomy indicating considerable uncertainty in the relationship among these taxa.
There remains substantial disagreement as to which taxon (or group) is most closely related to Euneomyini; analyses that include only Cytb and IRBP sequence data tend to suggest that this tribe forms a group (in some cases, with strong Bayesian but poor bootstrap support) with Chinchillula, followed by a clade that includes Andinomys and Punomys (e.g., Salazar-Bravo et al., 2013; Pardinas et al., 2014) or as a clade within a polytomy that also includes Chinchillula and Reithrodon (see Carrizo and Catalano, in press).
The presence of the fragmentary taxon "G." phuwiangensis creates a polytomy between Sunosuchus, Eutretauranosuchus and "G." phuwiangensis.
The large geographic range of the A.I.12 subgroup and the phylogenetic pattern of a long branch leading to a polytomy with genetic homogeneity point to a possible adaptive advantage for this subgroup.