Aims Many polyploids are geographically separated from their lower-ploidy progenitors at a variety of spatial scales.Diverse adaptive and non-adaptive mechanisms have been suggested to contribute to these spatial patt...Aims Many polyploids are geographically separated from their lower-ploidy progenitors at a variety of spatial scales.Diverse adaptive and non-adaptive mechanisms have been suggested to contribute to these spatial patterns.A long-standing hypothesis holds that poly-ploids are established and persist due to specialization to differ-ent ecological conditions compared to their progenitors.However,experimental approaches testing this hypothesis remain rare.Empirical evidence for niche differences among ploidy levels has been found previously for the European polyploid geophyte Allium oleraceum.Here,we conducted a 5-year reciprocal transplant experiment with tetraploid,pentaploid and hexaploid A.oleraceum to test for adaptation at the ploidy and population levels.Methods In 2006,we sowed 2160 aerial bulbils among six sites(two per cytotype,central and western Moravia,the Czech Republic)and monitored their emergence in 2007,their survival until 2011 and their performance in 2011.Important Findings The emergence of bulbils was high at all target sites,and no evi-dence for niche differentiation among cytotypes was recorded in the first year.Survival in the following years was relatively high,but significantly better survival for plants of home ploidy than foreign ploidy was recorded.No plant reached the reproductive stage during our experiment.Adopting a strict definition of local adaptation,local plants only rarely performed better than foreign plants at both sites in pairwise comparisons within a cytotype.Together,our results sug-gest weak niche differentiation among cytotypes and provide limited support for the existence of local adaptation within cytotypes.Thus,all cytotypes are able to establish in habitats typically populated by other cytotypes via aerial bulbil spread,but will likely die out gradually in non-native habitats.This ability may explain the occur-rence of some multiple-cytotype populations.The complex spatial pattern of A.oleraceum cytotypes is therefore the result of several interacting factors,including niche differentiation among cytotypes,the different evolutionary ages of cytotypes,the existence of gene flow between and within cytotypes,the dominance of clonality and stochastic events linked to anthropogenic dispersal and disturbance.展开更多
文摘Aims Many polyploids are geographically separated from their lower-ploidy progenitors at a variety of spatial scales.Diverse adaptive and non-adaptive mechanisms have been suggested to contribute to these spatial patterns.A long-standing hypothesis holds that poly-ploids are established and persist due to specialization to differ-ent ecological conditions compared to their progenitors.However,experimental approaches testing this hypothesis remain rare.Empirical evidence for niche differences among ploidy levels has been found previously for the European polyploid geophyte Allium oleraceum.Here,we conducted a 5-year reciprocal transplant experiment with tetraploid,pentaploid and hexaploid A.oleraceum to test for adaptation at the ploidy and population levels.Methods In 2006,we sowed 2160 aerial bulbils among six sites(two per cytotype,central and western Moravia,the Czech Republic)and monitored their emergence in 2007,their survival until 2011 and their performance in 2011.Important Findings The emergence of bulbils was high at all target sites,and no evi-dence for niche differentiation among cytotypes was recorded in the first year.Survival in the following years was relatively high,but significantly better survival for plants of home ploidy than foreign ploidy was recorded.No plant reached the reproductive stage during our experiment.Adopting a strict definition of local adaptation,local plants only rarely performed better than foreign plants at both sites in pairwise comparisons within a cytotype.Together,our results sug-gest weak niche differentiation among cytotypes and provide limited support for the existence of local adaptation within cytotypes.Thus,all cytotypes are able to establish in habitats typically populated by other cytotypes via aerial bulbil spread,but will likely die out gradually in non-native habitats.This ability may explain the occur-rence of some multiple-cytotype populations.The complex spatial pattern of A.oleraceum cytotypes is therefore the result of several interacting factors,including niche differentiation among cytotypes,the different evolutionary ages of cytotypes,the existence of gene flow between and within cytotypes,the dominance of clonality and stochastic events linked to anthropogenic dispersal and disturbance.
