Allozyme variation in Carex sect. Digitatae – Evidence of introgression, genetic distinctiveness and evolution of taxa

Abstract.

 A subset of populations of the European taxa of Carex sect. Digitatae, including Carex digitata, C. pallens, C. ornithopoda, C. pediformis ssp. rhizodes and C. humilis have been investigated for allozyme variation. The (presumably) distantly related C. pendula was used as a reference taxon. Carex digitata, C. pallens and C. ornithopoda on the one hand, and C. humilis and C. pediformis on the other, shared the majority of the alleles. Cluster analyses based on genetic distances grouped populations of C. digitata and C. ornithopoda in a mixed subcluster whereas all populations of C. pallens formed a subcluster distinct from the digitata/ornithopoda cluster. This in spite of the fact that C. ornithopoda is morphologically clearly distinct from C. digitata whereas C. pallens is barely distinguishable from the latter. Carex pediformis and C. humilis appeared not more genetically similar to C. digitata than to the reference taxon. It is concluded that 1) C. digitata, C. pallens and C. ornithopoda are closely related and most probably forms a monophyletic group, 2) C. pallens is a genetically distinct species, 3) C. pediformis and C. humilis are not closely related to the rest of C. sect. Digitatae, 4) C. pediformis and C. humilis are relatively closely related, 5) introgression do occur between the investigated species but not to such an extent that it can explain major geographic patterns of variation in C. digitata.