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Data from: Fitness of an allopolyploid rupicolous fern compared to its diploid progenitors: From sporogenesis to sporophyte formation


Pangua, Emilia; Pajarón, Santiago; Quintanilla, Luis G. (2019), Data from: Fitness of an allopolyploid rupicolous fern compared to its diploid progenitors: From sporogenesis to sporophyte formation, Dryad, Dataset,


PREMISE OF THE STUDY: When two populations of related cytotypes grow in sympatry, the rarer cytotype tends to be excluded due to a frequency-dependent mating disadvantage. Evolutionary models predict that polyploids, which are typically the rarer cytotype upon first formation, should have higher relative fitness and/or higher selfing rates to establish and then coexist with diploid parents. METHODS: We compared performance in early recruitment among three co-occurring rupicolous fern species: the allotetraploid Cheilanthes tinaei and its diploid ancestors, C. hispanica and C. maderensis. We made culture experiments with fresh spores and samples of soil spore banks to test for variation among cytotypes in germination, survival, growth and fecundity, and mating system of gametophytes. KEY RESULTS: Compared to its diploid parents, C. tinaei fresh spores had: higher abortion percentages, worselower dispersal ability due to larger spores, and similar vigor at germination. As for gametophytes from soil spore banks, C. tinaei showed high survival as C. maderensis, but its , similar germination percentage and similar time taken to germinate at each incubation temperature. Regarding soil spore banks, C. tinaei showed more abundant germination than both diploids, which supports greater spore deposition under sporophytes of the allotetraploid. Its gender expression resembles that of C. hispanica, with a high proportion of males. Patterns of sporophyte formation by females and bisexuals indicate that the polyploid does not have increased intragametophytic selfing rates. Gametophytes were larger in C. tinaei, but its reproductive success (sporophyte formation) was intermediate relative to diploids. CONCLUSIONS: Our results indicate that the allopolyploid show similar or even lower fitness than diploid progenitors show no evidence of higher selfing or fitness advantage of the allopolyploid over both diploid parents at any stage of early recruitment. In addition, all three species may have similar selfing rates. These two unexpected findings suggest that further factors, such as niche differentiation, play a more important role in cytotype coexistence.

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Iberian Peninsula