Format: ORAL

Valentin Heimer1,2, Jonas Geurden2, Andreas Hilpold1, Mingai Li3, Claudio Varotto3, Peter Schnswetter2, Božo Frajman2

1 Eurac Research, Bozen/Bolzano, Italy. 2 University of Innsbruck, Innsbruck, Austria. 3 Fondazione Edmund Mach, S. Michele all’Adige, Italy.

The diversification of flowering plants has been influenced by changes in the number and structure of chromosomes. While the evolutionary consequences of chromosome duplications (polyploidy) are well documented, much less is known about the effects of chromosome fragmentations (agmatoploidy). Luzula (Juncaceae) is a genus with common incidence of both phenomena, leading to a variety of cytotypes. The most variable and taxonomically intricate group within the genus is Luzula sect. Luzula, of which eight species with six karyotypes, including di-, tetra- and hexaploids, have been reported for the Eastern Alps. However, due to weak morphological differentiation among taxa, their distributions and phylogenetic relationships are insufficiently known. By using an integrated approach employing extensive vegetation surveys, relative genome size estimations, chromosome counts, RAD- and plastome sequencing, we aim at disentangling the evolutionary history and ecological niche segregation within this species complex. Combining a variety of different methods will allow us to reconstruct phylogenetic relationships among species as well as unravel the roles of chromosome duplication and fragmentation for speciation and ecological divergence in Luzula. During the talk we will present preliminary results of ecological and genomic data. Our findings include common co-occurrence of cytotypes at the same locality and a varying degree of ecological differentiation among taxa. In the (sub)alpine belt, we found tetraploid species to be more common on silicates while diploid L. exspectata occurs mostly on calcareous bedrock and L. sudetica is restricted to humid habitats.