Intraspecific variation in Viola suavis in Europe: parallel evolution of white-flowered morphotypes.
OBJECTIVE
Viola species are commonly grown for their ornamental flowers, but their evolutionary history and taxonomy are often complicated and have been poorly explored so far. This is a study of the polymorphic, typically blue-flowered species Viola suavis, concentrating on the white-flowered populations of uncertain taxonomic assignment that occur in Spain and central and south-eastern Europe. The aim was to resolve their origin and taxonomic status and to study the intraspecific structure and (post)glacial history of this species.


METHODS
Viola suavis and five close relatives were sampled from multiple locations and subjected to molecular (AFLP, sequencing of nrDNA ITS) and morphometric analyses. Data on ploidy level and pollen fertility were also obtained, to address an assumed hybrid origin of the white-flowered populations.


RESULTS
In V. suavis a strong intraspecific genetic split into two groups was observed, indicating that there has been a long-term isolation and survival in distinct glacial refugia. The white-flowered populations could be placed within the variation range of this species, and it is clear that they evolved independently in two distant areas. Their parallel evolution is supported by both morphological and genetic differentiation. The strongly reduced genetic variation and absence of unique AFLP fragments suggest their derived status and origin from the typical, blue-flowered populations.


CONCLUSIONS
These results suggest that intraspecific variation in V. suavis has been largely shaped by population isolations during the last glaciation and subsequent recolonizations, although cultivation and vegetative spread by humans have affected the present picture as well.
Mereda
P
P
Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 14, SK-845 23 Bratislava, Slovak Republic. pavol.mereda@savba.sk
Hodálová
I
I
Mártonfi
P
P
Kucera
J
J
Lihová
J
J
D054458:Amplified Fragment Length Polymorphism Analysis; D005075:Biological Evolution; D002678:Chimera / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics*; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D005060:Europe; D005298:Fertility / Q000235:genetics; D035264:Flowers / Q000145:classification / Q000235:genetics* / Q000502:physiology; D014644:Genetic Variation; D005828:Genetics, Population; D015999:Multivariate Analysis; D010802:Phylogeny; D011003:Ploidies; D011058:Pollen / Q000235:genetics; D025341:Principal Component Analysis; D017422:Sequence Analysis, DNA; D032413:Viola / Q000145:classification / Q000235:genetics* / Q000502:physiology
D018744:DNA, Plant; D021903:DNA, Ribosomal Spacer