Data from: Molecular evidence for the compilospecies model of reticulate evolution in Armeria (Plumbaginaceae)

Cladistic analyses of the nuclear ribosomal DNA (nrDNA) internal
transcribed spacer (ITS) sequences from 55 samples corresponding to 34
taxa in the genus Armeria reveal that ITS sequence diversity among and
within species utterly conflicts with patterns of morphological
similarity. Three facts are apparent from the results here reported: (1)
different samples of a single subspecies, A. villosa subsp. longiaristata,
appear in three of the five major clades; (2) samples of at least one of
the six subspecies of A. villosa appear in four of the five major clades;
and (3) composition of major clades shows greater congruence with the
geographic origin of plants than with the traditional systematic
arrangement based primarily on morphology. Specifically, the clades here
termed Ia, II, III, and IV each encompass terminals restricted to
geographically delimited areas. There are alternative explanations for the
ITS pattern, but the most likely one is that nucleotide positions
supporting the major clades are due, in some of the samples, to concerted
evolution following horizontal transfer (gene flow) rather than to recency
of common ancestry. This interpretation is consistent with previous
systematic and experimental evidence and implies that reticulation in
Armeria may be extensive. Harlan and de Wet (1963, Evolution 17:497-501)
proposed the compilospecies concept to account for situations in which a
genetically "aggressive" species captures portions of the genome
of other sympatric species via extensive introgression. Evidence of
extensive reticulation, ecological diversification, and geographic pattern
indicates that A. villosa may fit the compilospecies concept, which is
here supported on molecular grounds for the first time.