Here again, the diploid races are glacial relicts, that form tessellated patterns throughout European mountainous areas. In contrast, the post-glacial octoploids are widely and evenly distributed. Diploid races live in the formerly unfrozen glacial valleys. When the ice retreated, tetraploid races re-populated the Alpine ranges and spread from there to Southern Europe. Diploid and tetraploid populations of Asplenium trichomans do not differ morphologically.
Diploid races prefer acidic, tetraploid races basic soils.
Ranunculus ficaria populations with 2x, 4x, 5x, and 6x occur in Europe. Each of them displays minor, though significant morphological variations. Everywhere, where both diploid and tetraploid races occupy the same area, the tetraploid races differ from the diploid races by a set of site-specific features, i.e. no unique features distinguish the tetraploid from the diploid. It seems instead, as if the increase in ploidy provides the plant with more flexibility in expressing its genome. It can thus react with different strategies to the variable challenges of its environment.