speciation

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spe·ci·a·tion

(spē'shē-ā'shŭn),
The evolutionary process by which diverse species of animals or plants are formed from a common ancestral stock.

speciation

(spē′shē-ā′shən, -sē-)
n.
The formation of new biological species through the process of evolution.

spe′ci·ate′ v.
spe′ci·a′tion·al adj.

spe·ci·a·tion

(spē'shē-ā'shŭn)
The evolutionary process by which diverse species of animals or plants are formed from a common ancestral stock.

speciation

the process by which new species are formed. Speciation occurs when gene flow has effectively ceased between populations where it previously existed and is brought about by ISOLATING MECHANISMS.see GEOGRAPHICAL ISOLATION.
References in periodicals archive ?
Speciational evolution: a phylogenetic test with allozymes in Sceloporus (Reptilia).
Weighted squared-change parsimony was used with the gradual simulations and unweighted squared-change parsimony was used with speciational simulations [ILLUSTRATION FOR FIGURE 2 OMITTED].
The choice of boundary options influences the distribution of the simulated changes in both speciational and gradual evolution simulations ([ILLUSTRATION FOR FIGURE 2 OMITTED], step 1).
Figure 6a compares the distributions of changes produced in the speciational Unbounded simulations (indicated by a line) with the distribution of changes reconstructed by linear or squared-change parsimony (indicated by bars).
If branch lengths are obtained by assuming a model of phenotypic evolution that makes them directly proportional to some aspect of the phylogeny (e.g., under gradual or speciational models of change), p(BL/P) is implicitly assumed to be 1 and [Var.sub.BL] is assumed to equal 0.
For the speciational and punctuational models, the amount of character change was sampled from a Poisson distribution with its parameter adjusted to match the total expected amount of change in the phyletic model.
These authors distinguished among: (1) the phyletic context, where character state changes may occur anywhere along a given tree; (2) the speciational context, where character state changes are assumed to occur only during a speciation event and in both daughter lineages; and (3) the punctuational context, where character state changes are assumed to occur only in one daughter species at the time of a speciation event.
NJ is more accurate than the other two under the punctuated and speciational context models.