Reproductive strategies of sexually dimorphic plants vary in response to the environment.Here,we ask whether the sexual systems of Fagopyrum species(i.e.,selfing homostylous and out-crossing distylous)represent distin...Reproductive strategies of sexually dimorphic plants vary in response to the environment.Here,we ask whether the sexual systems of Fagopyrum species(i.e.,selfing homostylous and out-crossing distylous)represent distinct adaptive strategies to increase reproductive success in changing alpine environments.To answer this question,we determined how spatial and temporal factors(e.g.,elevation and peak flowering time)affect reproductive success(i.e.,stigmatic pollen load)in nine wild Fagopyrum species(seven distylous and two homostylous)among 28 populations along an elevation gradient of 1299-3315 m in the Hengduan Mountains,southwestern China.We also observed pollinators and conducted hundreds of hand pollinations to investigate inter/intra-morph compatibility,self-compatibility and pollen limitation in four Fagopyrum species(two distylous and two homostylous).We found that Fagopyrum species at higher elevation generally had bigger flowers and more stigmatic pollen loads;lateflowering individuals had smaller flowers and lower pollen deposition.Stigmatic pollen deposition was more variable in distylous species than in homostylous species.Although seed set was not pollenlimited in all species,we found that fruit set was much lower in distylous species,which rely on frequent pollinator visits,than in homostylous species capable of autonomous self-pollination.Our findings that pollination success increases at high elevations and decreases during the flowering season suggest that distylous and homostylous species have spatially and temporally distinct reproductive strategies related to environment-dependent pollinator activity.展开更多
Aims Distyly has been regarded as an adaptation to improve compatible pollination between two floral morphs with reciprocal herkogamy.The hypothesis that the different positions of anthers and stigmas within flowers a...Aims Distyly has been regarded as an adaptation to improve compatible pollination between two floral morphs with reciprocal herkogamy.The hypothesis that the different positions of anthers and stigmas within flowers as well as their reciprocal position between morphs,reduce the probability of self pollination raised by Darwin has been rarely tested.in this study,we measured stigmatic pollen loads in response to reduced reciprocal herkogamy in two Primula species.Methods To see whether reciprocal herkogamy can increase compatible and/or reduce incompatible pollen deposition,thus promoting compat-ible pollination,we shortened the distance between anthers and stigmas within the flowers by changing the position of the corolla tube,to which the anthers were fused,i.e.reduced herkogamy in natural populations of Primula secundiflora and P.poissonii and quantified stigmatic pollen loads in the field over 2 years.Important Findingsin both species,stigmatic pollen loads were significantly higher in the long-styled(l-morph)than in the short-styled morph(s-morph)in both control and manipulated flowers,but percentage of compatible pollen in s-morph were higher.Flowers manipulated to halve the anther-stigma distance showed a similar pattern for 2 years:total pollen grain counts on stigmas did not differ significantly but compatible pollen grains in l-and s-morphs were significantly decreased in both species.The percentage of compatible pollen loads was decreased by 68.7%in P.secundiflora and 65.3%in P.poissonii in l-morphs,while it decreased by 30.6%and 2.9%in s-morphs,respectively.our manipulation of the relative position of anthers and stigmas in the two distylous species indicated that a lower degree of herkogamy reduced compatible but incompatible pollen transfer was likely to increase.The higher proportion of compatible pollen in the s-morph than in the l-morph in the two Primula species could be attributed to the accessibility of two-level sexual organs,floral orientations and pollinator behaviors.This is a first attempt to manipulate intraflower herkogamy for understanding adaptation of heterostyly,shedding insights into how the reciprocal herkogamy promotes compatible pollination.展开更多
基金supported by the National Natural Science Foundation of China(Nos.31900204,32071671,32030071)the Postdoctoral Research Foundation of China(grant no.2019M652674)the Fundamental Research Funds for the Central Universities(grant no.CCNU22LJ003).
文摘Reproductive strategies of sexually dimorphic plants vary in response to the environment.Here,we ask whether the sexual systems of Fagopyrum species(i.e.,selfing homostylous and out-crossing distylous)represent distinct adaptive strategies to increase reproductive success in changing alpine environments.To answer this question,we determined how spatial and temporal factors(e.g.,elevation and peak flowering time)affect reproductive success(i.e.,stigmatic pollen load)in nine wild Fagopyrum species(seven distylous and two homostylous)among 28 populations along an elevation gradient of 1299-3315 m in the Hengduan Mountains,southwestern China.We also observed pollinators and conducted hundreds of hand pollinations to investigate inter/intra-morph compatibility,self-compatibility and pollen limitation in four Fagopyrum species(two distylous and two homostylous).We found that Fagopyrum species at higher elevation generally had bigger flowers and more stigmatic pollen loads;lateflowering individuals had smaller flowers and lower pollen deposition.Stigmatic pollen deposition was more variable in distylous species than in homostylous species.Although seed set was not pollenlimited in all species,we found that fruit set was much lower in distylous species,which rely on frequent pollinator visits,than in homostylous species capable of autonomous self-pollination.Our findings that pollination success increases at high elevations and decreases during the flowering season suggest that distylous and homostylous species have spatially and temporally distinct reproductive strategies related to environment-dependent pollinator activity.
基金National Science Foundation of China(31030016,31270281)to S.Q.H.
文摘Aims Distyly has been regarded as an adaptation to improve compatible pollination between two floral morphs with reciprocal herkogamy.The hypothesis that the different positions of anthers and stigmas within flowers as well as their reciprocal position between morphs,reduce the probability of self pollination raised by Darwin has been rarely tested.in this study,we measured stigmatic pollen loads in response to reduced reciprocal herkogamy in two Primula species.Methods To see whether reciprocal herkogamy can increase compatible and/or reduce incompatible pollen deposition,thus promoting compat-ible pollination,we shortened the distance between anthers and stigmas within the flowers by changing the position of the corolla tube,to which the anthers were fused,i.e.reduced herkogamy in natural populations of Primula secundiflora and P.poissonii and quantified stigmatic pollen loads in the field over 2 years.Important Findingsin both species,stigmatic pollen loads were significantly higher in the long-styled(l-morph)than in the short-styled morph(s-morph)in both control and manipulated flowers,but percentage of compatible pollen in s-morph were higher.Flowers manipulated to halve the anther-stigma distance showed a similar pattern for 2 years:total pollen grain counts on stigmas did not differ significantly but compatible pollen grains in l-and s-morphs were significantly decreased in both species.The percentage of compatible pollen loads was decreased by 68.7%in P.secundiflora and 65.3%in P.poissonii in l-morphs,while it decreased by 30.6%and 2.9%in s-morphs,respectively.our manipulation of the relative position of anthers and stigmas in the two distylous species indicated that a lower degree of herkogamy reduced compatible but incompatible pollen transfer was likely to increase.The higher proportion of compatible pollen in the s-morph than in the l-morph in the two Primula species could be attributed to the accessibility of two-level sexual organs,floral orientations and pollinator behaviors.This is a first attempt to manipulate intraflower herkogamy for understanding adaptation of heterostyly,shedding insights into how the reciprocal herkogamy promotes compatible pollination.
