Format: ORAL

Shook Ling Low1, Yann J.K. Bertrand1, Simon V. Corrales1, Elika Zvesk1, Vojtech Zeisek1,2, Begoa Quirs-de-la-Pea1,2,Patrik Mrz2, Jindrich Chrtek1,2

1 Institute of Botany, Czech Academy of Sciences, Pruhonice, Czechia 2 Department of Botany, Charles University, Prague, Czechia

Interglacial refugia serve as counterpoint to glacial refugia for cold-adapted species widely distributed during the glacial maxima but forced to retreat due to changing climatic conditions and increasing competition from new immigrants during interglacial periods. European sky islands function as climate refugia for many hybridogeneous species whose origin might be clouded by demographic processes like founder effect, bottleneck, selection and genetic drift. Yet in allopolyploid apomictic species, i.e. hybridogeneous species which reproduce by seeds without fertilization, severe gene flow reduction and few meiotic rearrangements, preserve the progenitor genotypes and therefore allows for exploring previous contacts and subsequent local extinctions of their parental lineages. We explored the origin, genomic composition and post-polyploidization population dynamics of the apomict Hieracium halleri (triploid and tetraploid) that evolved through hybridization between diploid H. intybaceum (2n=18) and diploid or triploid H. alpinum (2n=18, 27). We aimed to investigate the tempo of recurrent establishment of asexual cytotypes of H. halleri, elucidate whether the differences in evolutionary histories of these cytotypes is reflected in their genetic variation, morphology, recent distribution, and ecology. The genetic structure of hybridogeneous apomictic species and its progenitors was explored using RADseq loci. For the allopolyploid apomicts, haplotypes were obtained with alignment-based phasing that segregated data originated from the parental subgenomes. We performed chromosome scale assembly of one of the progenitors (H. alpinum, genome size ~ 4G) and created a pseudoreference for the other by RAD loci concatenation. The repeated independent polyploidization events were dated using whole plastome and Hybseq low-copy nuclear genes alignments. We also presented the read-mapping approach method to identify subgenomes in hybrid. Thus, an integrative approach allowed us to decipher evolutionary history and biogeography of this widely distributed apomict.