| Summary: | It has been suggested that polyploidization affects the ecological niche of a species, possibly ultimately leading to a shift in the distribution of the species, such as in geographical parthenogenesis. The phenomenon describes the wider distribution and shift of asexuals towards higher altitudes, northern latitudes and more extreme habitats when compared with their closely related sexual relatives. Several hypotheses have been proposed to explain such patterns with lacking empirical evidence because investigations rather focused on single hypotheses, which were rather tested several times independently on multiple organisms than vice versa. Therefore, the present study aimed to tackle the phenomenon of geographical parthenogenesis from multiple angles, i.e. testing several hypotheses simultaneously using Hieracium alpinum as a model system. In the arcto-alpine Asteraceae H. alpinum sexually reproducing diploid individuals occur in a small isolated area in the Eastern and Southern Carpathians, while apomictically reproducing, i.e. asexual reproduction via seeds, triploid plants occupy the remaining and much larger part of the range from the Balkans to the arctic parts of Europe. This implies that asexual triploids have had some fitness / colonization advantage(s), leading to a replacement of sexual diploids. It has been suggested that polyploidization affects the ecological niche of a species, possibly ultimately leading to a shift in the distribution of the species, such as in geographical parthenogenesis. The phenomenon describes the wider distribution and shift of asexuals towards higher altitudes, northern latitudes and more extreme habitats when compared with their closely related sexual relatives. Several hypotheses have been proposed to explain such patterns with lacking empirical evidence because investigations rather focused on single hypotheses, which were rather tested several times independently on multiple organisms than vice versa. Therefore, the present study aimed to tackle the phenomenon of geographical parthenogenesis from multiple angles, i.e. testing several hypotheses simultaneously using Hieracium alpinum as a model system. In the arcto-alpine Asteraceae H. alpinum sexually reproducing diploid individuals occur in a small isolated area in the Eastern and Southern Carpathians, while apomictically reproducing, i.e. asexual reproduction via seeds, triploid plants occupy the remaining and much larger part of the range from the Balkans to the arctic parts of Europe. This implies that asexual triploids have had some fitness / colonization advantage(s), leading to a replacement of sexual diploids. Katedra botaniky Department of Botany Přírodovědecká fakulta Faculty of Science
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