Abstract
Polyploidisation—and, additionally, agmatoploidy (concerted fission of chromosomes) in some plant groups—have significantly contributed to the diversification of alpine plant species. Both processes have driven the diversification of Luzula sect. Luzula, leading to a number of different karyotypes, rendering it one of the most intricate plant groups in the Alps. For the Eastern Alps eight species with six karyotypes were reported, but their distribution is insufficiently known. A herbarium revision of 1044 specimens revealed that L. alpina, L. campestris, L. exspectata, L. multiflora and L. sudetica are widespread across the Eastern Alps; L. exspectata is thus new for the Northern Alps and new for Germany, France and possibly Croatia. Luzula divulgata is distributed in the easternmost Alps and adjacent areas, with only a few indications for the western Eastern Alps. Luzula divulgatiformis is new for the Alps where it was recorded in the Southern Alps and southerly adjacent areas. Luzula campestris, L. divulgata and L. divulgatiformis are distributed from lowlands to the montane belt, L. alpina, L. exspectata and L. sudetica are high-elevation species and L. multiflora occurs from lowlands to the alpine belt. Additionally, we estimated genome size (GS) and karyotypes for 20 populations and revealed four karyotypes corresponding to three ploidy levels. The GS of diploid L. exspectata and L. sudetica was 0.83 pg DNA, tetraploid L. alpina had a double (1.63 pg) and hexaploid L. multiflora a triple (2.48 pg) GS. Our study underlines the importance of large-scale herbarium revisions of intricate taxa, combined with cytological methods, even in well-studied mountain areas such as the Alps and poses new hypotheses regarding the evolution of this polyploid–agmatoploid group.
Highlights
Distribution of species in the Eastern Alps based on the revision of herbarium specimens The revision of 1044 specimens confirmed the presence of seven species (Fig. 1, Online Resource 1) in the Eastern Alps—L. alpina (91 specimens), L. campestris (307 specimens), L. divulgata (27 specimens), L. divulgatiformis (31 specimens), L. exspectata (158 specimens), L. multiflora (250 specimens) and L. sudetica (111 specimens)
Whereas L. alpina, L. campestris, L. exspectata, L. multiflora and L. sudetica are widespread across the Eastern Alps, L. divulgata is mostly limited to the easternmost Northern Alps and adjacent areas, with only a few indications for the western Eastern Alps, and L. divulgatiformis occurs only in the Southern Alps and southerly adjacent areas (Fig. 1)
As all high-elevation taxa are either agmatoploid (L. exspectata and L. sudetica), polyploid (L. multiflora) or both processes have been involved in their origin (L. alpina)
Summary
With more than 4000 vascular plant species, the Alps are one of the hotspots of European biodiversity, harbouring many endemics; in many respects they are the beststudied mountain range of the world The Eastern Alps, harbouring 3720 vascular plant taxa (Aeschimann et al 2011b) consist of the siliceous Central Alps flanked to the south and north by the peripheral Southern and Northern Limestone Alps (Möbus 1997). This tripartite structure of different bedrocks highly affects the distribution ranges of alpine plants, as substrate is one of the key factors influencing plant distributions (Alvarez et al 2009). This approach is not suitable for large-scale studies, but can be substituted by detailed revision of herbarium specimens employing measurements of micromorphological characters
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