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Single cytotype areas in autopolyploid Plantago media L.*

1992; Oxford University Press; Volume: 46; Issue: 4 Linguagem: Inglês

10.1111/j.1095-8312.1992.tb00867.x

1095-8312

Peter R. van Dijk, Marijke Hartog, W. van Delden,

Plant Reproductive Biology

The European distribution of diploid and tetraploid cytotypes of Plantago media has been studied on three different scales: Europe as a whole, the Pyrenees and the upper Rio Gallego valley (Central Pyrenees). On a European scale, the tetraploids are widely and more or less continuously distributed; the diploids are restricted and disjunct. In the Pyrenees the distributions are essentially parapatric with diploids occupying the western part and tetraploids the eastern part. The overlap zone in the Rio Gallego valley consists of a mosaic of diploid, tetraploid and mixed populations. The Pyrenean distribution is best explained by colonization by cytotypes from different origins during the late glacial period followed by secondary contact. The limited intermingling of cytotypes is explained by exclusion, probably genetic and possibly also ecological. Reduced fitness of hybrid cytotypes may account for the existence of large areas with a single cytotype ('single cytotype areas') in allopolyploid species in general.