Mycorrhizal symbioses are prevalent in terrestrial ecosystems and play essential roles in plant nutrition and health.However,the relative importance of plant evolutionary history,physiology,and eco-geographical factor...Mycorrhizal symbioses are prevalent in terrestrial ecosystems and play essential roles in plant nutrition and health.However,the relative importance of plant evolutionary history,physiology,and eco-geographical factors in shaping mycorrhizal fungal community assembly remains poorly understood.Here,we investigate how plant phylogeny,trophic mode,biogeographic distribution and environmental niche collectively influence the diversity and composition of mycorrhizal fungal communities across the Orchidaceae,spanning broad phylogenetic and ecological scales.By using family-wide orchid-fungal associations and global occurrence data,our analyses showed that the variation in fungal diversity and community structure can be partially explained by orchids’trophic mode,biogeographic distribution and environmental niche,but not by their overall phylogenetic relatedness.Among trophic modes,partially mycoheterotrophic orchids exhibited the highest level of fungal diversity(the lowest level of fungal specificity)in association with a broad range of phylogenetically dispersed fungal partners.Between biogeographical regions,a significantly higher level of fungal specificity was found for orchid species distributed in Australia than those in Eurasia and Africa.Furthermore,multivariate analyses showed that a small portion of the variation in fungal community structure was significantly related to broad climate,soil and vegetation variables,indicating the existence of large-scale habitat filtering on orchid mycorrhizal communities.Altogether,our findings indicate that mycorrhizal communities in the orchid family are likely shaped by multiple,intertwined factors related to orchid ecophysiology and biogeography on a global scale.展开更多
Aims Closely related species frequently co-occur in plant communities.The role of niche partitioning for allowing their coexistence has been called into question,but most studies on community ecol-ogy neglect pollinat...Aims Closely related species frequently co-occur in plant communities.The role of niche partitioning for allowing their coexistence has been called into question,but most studies on community ecol-ogy neglect pollination as a niche component,and thus poten-tially underestimate niche partitioning.Here,we investigate the importance of the pollination niche for determining coexistence in a biodiversity hotspot.We specifically test whether co-flowering insect-pollinated species of Erica,the most species-rich plant genus of the South African Cape Floristic Region,are characterized by dif-ferent functional floral traits and different specialized pollination systems.Methods Communities of co-flowering Erica species were studied at three sites in the fynbos biome in the Western Cape of South Africa.We focused on five species with flowers that conform to an insect pol-lination syndrome.We assessed whether floral traits important for pollinator attraction and mechanical fit overlap by comparison of scent(gas chromatography coupled with mass spectrometry),col-our(spectrophotometry and models of bee vision),nectar volume and concentration and corolla morphology.Pollinator partitioning was quantified by comparison of floral visitor profiles and pollinator importance,calculated as the product of visitation rate,number of flowers probed per visit and pollen load for each functional visitor group among species within communities.Potential effects of com-petition were assessed by comparing visitation rates both directly and using anther ring disturbance as a proxy for lifetime visitation.Important Findings Floral phenotypes differed among species within communities in all functional traits.Visitor assemblages were diverse,including ants,beetles,flies,honeybees,moths and solitary bees.However,the Cape honeybee,Apis mellifera capensis,was the main pollinator of all but one Erica species.Insect visitation rates were significantly lower for E.imbricata and E.calycina relative to congeners,but high rates of anther ring disturbance,which differed significantly in only two out of seven comparisons,suggest that long-term visitation rates are mostly similar among species that share pollinators.This study shows that coexistence of co-flowering insect-pollinated Erica species is not determined by specialization for different pollination systems.Pollinator sharing might rather lead to facilitation among co-flowering species,and floral constancy mediated by extensive interspecific floral trait variation might mitigate its potentially nega-tive effects.展开更多
基金the funding provided by the China Scholarship Council(Grant No.201804910634)the Ecology Fund of the Royal Netherlands Academy of Arts and Sciences(KNAWWF/807/19039)to Deyi Wang.
文摘Mycorrhizal symbioses are prevalent in terrestrial ecosystems and play essential roles in plant nutrition and health.However,the relative importance of plant evolutionary history,physiology,and eco-geographical factors in shaping mycorrhizal fungal community assembly remains poorly understood.Here,we investigate how plant phylogeny,trophic mode,biogeographic distribution and environmental niche collectively influence the diversity and composition of mycorrhizal fungal communities across the Orchidaceae,spanning broad phylogenetic and ecological scales.By using family-wide orchid-fungal associations and global occurrence data,our analyses showed that the variation in fungal diversity and community structure can be partially explained by orchids’trophic mode,biogeographic distribution and environmental niche,but not by their overall phylogenetic relatedness.Among trophic modes,partially mycoheterotrophic orchids exhibited the highest level of fungal diversity(the lowest level of fungal specificity)in association with a broad range of phylogenetically dispersed fungal partners.Between biogeographical regions,a significantly higher level of fungal specificity was found for orchid species distributed in Australia than those in Eurasia and Africa.Furthermore,multivariate analyses showed that a small portion of the variation in fungal community structure was significantly related to broad climate,soil and vegetation variables,indicating the existence of large-scale habitat filtering on orchid mycorrhizal communities.Altogether,our findings indicate that mycorrhizal communities in the orchid family are likely shaped by multiple,intertwined factors related to orchid ecophysiology and biogeography on a global scale.
基金This project was funded by the Alberta Mennega Foundation,the Leiden University Fund(LUF)and the National Research Foundation(South Africa).
文摘Aims Closely related species frequently co-occur in plant communities.The role of niche partitioning for allowing their coexistence has been called into question,but most studies on community ecol-ogy neglect pollination as a niche component,and thus poten-tially underestimate niche partitioning.Here,we investigate the importance of the pollination niche for determining coexistence in a biodiversity hotspot.We specifically test whether co-flowering insect-pollinated species of Erica,the most species-rich plant genus of the South African Cape Floristic Region,are characterized by dif-ferent functional floral traits and different specialized pollination systems.Methods Communities of co-flowering Erica species were studied at three sites in the fynbos biome in the Western Cape of South Africa.We focused on five species with flowers that conform to an insect pol-lination syndrome.We assessed whether floral traits important for pollinator attraction and mechanical fit overlap by comparison of scent(gas chromatography coupled with mass spectrometry),col-our(spectrophotometry and models of bee vision),nectar volume and concentration and corolla morphology.Pollinator partitioning was quantified by comparison of floral visitor profiles and pollinator importance,calculated as the product of visitation rate,number of flowers probed per visit and pollen load for each functional visitor group among species within communities.Potential effects of com-petition were assessed by comparing visitation rates both directly and using anther ring disturbance as a proxy for lifetime visitation.Important Findings Floral phenotypes differed among species within communities in all functional traits.Visitor assemblages were diverse,including ants,beetles,flies,honeybees,moths and solitary bees.However,the Cape honeybee,Apis mellifera capensis,was the main pollinator of all but one Erica species.Insect visitation rates were significantly lower for E.imbricata and E.calycina relative to congeners,but high rates of anther ring disturbance,which differed significantly in only two out of seven comparisons,suggest that long-term visitation rates are mostly similar among species that share pollinators.This study shows that coexistence of co-flowering insect-pollinated Erica species is not determined by specialization for different pollination systems.Pollinator sharing might rather lead to facilitation among co-flowering species,and floral constancy mediated by extensive interspecific floral trait variation might mitigate its potentially nega-tive effects.
