Karyological analysis of the five native Macaronesian Festuca (Gramineae) grasses supports a distinct diploid origin of two schizoendemic groups

Abstract

A karyological analysis has been conducted of all five native Macaronesian Festuca grasses belonging to fine-leaved F. subg. Festuca sect. Aulaxyper and broad-leaved F. subg. Drymanthele sect. Phaeochloa Loliinae lineages. Chromosomal analyses were made in 30 plants corresponding to 17 populations of the fineleaved F. agustinii, F. jubata, F. francoi and F. petraea and 2 populations of the broad-leaved F. donax. All counts except one tetraploid count were diploids, showing 2n = 14 chromosomes. Diploidy was confirmed for the robust F. donax, nested within a clade of relict ancestral fescues as reported in recent phylogenetic studies, and was also found in the more slender F. agustinii, F. jubata, F. francoi and F. petraea, which are basal to a recently evolved clade of polyploid red fescues. Karyotypes of the two groups are however distinct, with broad-leaved F. donax showing larger and more regular chromosomes and all four fine-leaved taxa showing smaller and more irregular submetacentric chromosomes. Our karyological data indicate that these two groups of diploid fescues correspond to distinct schizoendemics which apparently originated at different times after independent continental colonizations of Macaronesia.

Keywords

• diploidy
• festuca agustinii
• f. donax
• f. francoi
• f. jubata
• f. petraea
• karyology