The anther-smut Microbotryum violaceum ( Brandenburger and Schvinn) G. Deml. and Oberw.) causes a systematic infection of its host Silene dioica ( L.) Clairv., resulting in sterility and production of teliospores (dis...The anther-smut Microbotryum violaceum ( Brandenburger and Schvinn) G. Deml. and Oberw.) causes a systematic infection of its host Silene dioica ( L.) Clairv., resulting in sterility and production of teliospores (dispersal propagules) in flowers. These spores are transmitted to healthy plants mainly by flower visitors. The behavioral responses of flower visitors to a variation in floral characters are not only likely to affect rates of pollen export/import, but also the rate of spore deposition and probability of disease. In a transplantation experiment, using plants from four different populations, we tested for correlation between variation in female floral morphology and patterns of spore and pollen deposition, and a resulting risk of disease. The source populations in this experiment were located on four islands in Skeppsvik archipelago in northern Sweden, and represented a gradient of disease incidence from completely healthy ( Island 1), low incidence ( Island 2) to high incidences ( Islands 3 and 4) of disease. Fifty plants from each population were transplanted to the center, of the population on Island 4. There were significant differences among the transplants in floral characters, i.e. corolla size, style length and ovule number. Plants from the non-diseased population had larger flowers and longer styles than plants from the highly diseased populations. Numbers of pollen grains and spores deposited on flowers were strongly and positively correlated. We found that plants originating from the non-diseased population captured approximately 4 times more pollen and 9 times more spores, per flower than die individuals from the resident population (Island 4, population 4). The incidences of disease among plants, from the four populations differed significantly, and was 37%, 20%, 18% and 0 for populations 1, 2, 3 and 4 respectively. In a survey of ten populations we found a significant negative correlation between the mean style length ( positively correlated with corolla size and ovule number) among healthy plants and incidence of disease in these populations. The potentiality for pathogen-pollinator mediated selection oil floral characters; and consequences for gone flow between populations of Silene dioica are discussed.展开更多
Aims Identifying the potential role of vegetation context(defined as the density,species identity/diversity and height of co-occurring plants)in modifying selection on floral traits is a critical step for clarifying a...Aims Identifying the potential role of vegetation context(defined as the density,species identity/diversity and height of co-occurring plants)in modifying selection on floral traits is a critical step for clarifying and predicting the floral evolutionary trajectory in complex co-flowering species competition environments.It is also helpful to understand the variation in pollinator-mediated selection.Methods We experimentally reduced vegetation height around individual plants of Spiranthes sinensis(a bumblebee-pollinated perennial orchid herb)and estimated how vegetation context modified selection on four floral traits(flowering start,plant height,corolla size and number of flowers)through female function and pollen removal over two continuous years.We randomly selected independent plants in each year.Important Findings We demonstrated that vegetation context modified selection for earlier flowering start and shorter plant height of S.sinensis.The strength of selection differed between years.In addition,selection was stronger through female function than through pollen removal.Our findings indicate the potential role of vegetation context in shaping the differentiation and diversification of flowers in angiosperms.展开更多
文摘The anther-smut Microbotryum violaceum ( Brandenburger and Schvinn) G. Deml. and Oberw.) causes a systematic infection of its host Silene dioica ( L.) Clairv., resulting in sterility and production of teliospores (dispersal propagules) in flowers. These spores are transmitted to healthy plants mainly by flower visitors. The behavioral responses of flower visitors to a variation in floral characters are not only likely to affect rates of pollen export/import, but also the rate of spore deposition and probability of disease. In a transplantation experiment, using plants from four different populations, we tested for correlation between variation in female floral morphology and patterns of spore and pollen deposition, and a resulting risk of disease. The source populations in this experiment were located on four islands in Skeppsvik archipelago in northern Sweden, and represented a gradient of disease incidence from completely healthy ( Island 1), low incidence ( Island 2) to high incidences ( Islands 3 and 4) of disease. Fifty plants from each population were transplanted to the center, of the population on Island 4. There were significant differences among the transplants in floral characters, i.e. corolla size, style length and ovule number. Plants from the non-diseased population had larger flowers and longer styles than plants from the highly diseased populations. Numbers of pollen grains and spores deposited on flowers were strongly and positively correlated. We found that plants originating from the non-diseased population captured approximately 4 times more pollen and 9 times more spores, per flower than die individuals from the resident population (Island 4, population 4). The incidences of disease among plants, from the four populations differed significantly, and was 37%, 20%, 18% and 0 for populations 1, 2, 3 and 4 respectively. In a survey of ten populations we found a significant negative correlation between the mean style length ( positively correlated with corolla size and ovule number) among healthy plants and incidence of disease in these populations. The potentiality for pathogen-pollinator mediated selection oil floral characters; and consequences for gone flow between populations of Silene dioica are discussed.
基金This research was supported by the Funds of the Science and Technology Department of Sichuan Province(2019YJ0393,2020YFSO309)Joint Funds of the National Natural Science Foundation of China and Yunnan Provincial Government(U1602263).
文摘Aims Identifying the potential role of vegetation context(defined as the density,species identity/diversity and height of co-occurring plants)in modifying selection on floral traits is a critical step for clarifying and predicting the floral evolutionary trajectory in complex co-flowering species competition environments.It is also helpful to understand the variation in pollinator-mediated selection.Methods We experimentally reduced vegetation height around individual plants of Spiranthes sinensis(a bumblebee-pollinated perennial orchid herb)and estimated how vegetation context modified selection on four floral traits(flowering start,plant height,corolla size and number of flowers)through female function and pollen removal over two continuous years.We randomly selected independent plants in each year.Important Findings We demonstrated that vegetation context modified selection for earlier flowering start and shorter plant height of S.sinensis.The strength of selection differed between years.In addition,selection was stronger through female function than through pollen removal.Our findings indicate the potential role of vegetation context in shaping the differentiation and diversification of flowers in angiosperms.
