Aims Floral nectar plays a vital role in plant reproductive success by attracting pollinators.Nectar traits of a flower can depend directly on plant characteristics other than environmental factors and exhibit extensi...Aims Floral nectar plays a vital role in plant reproductive success by attracting pollinators.Nectar traits of a flower can depend directly on plant characteristics other than environmental factors and exhibit extensive flower-and plant-level variations.studies on nectar traits frequently focused on intraplant variation for dichogamous plants,but few have paid attention to both intra-and interplant nectar variations in relation to plant characteristics.revealing within-and among-plant variation and its relative magnitude is important for our understanding of how pollinator-mediated selection can act on nectar traits and evolution of nectar traits.Methods Through investigating protandrous Aconitum gymnandrum populations at the alpine meadows and Wetland Ecosystems research station of lanzhou university,we examined the relationships between nectar production per flower and plant characteristics(e.g.flower position within inflorescences,flo-ral sexual phases,flowering time,inflorescence size and floral attractive traits).Important Findings A.gymnandrum exhibited a declining gradient in the nectar volume along inflorescences,with more nectar in basal flowers than distal ones.Protandrous flowers of A.gymnandrum did not show gender-biased nectar production while the nectar volume varied with differ-ent stages of floral sexual phases.The significant correlation between the first flowering date of individuals and the mean nectar volume per flower was positive in 2013,but became negative in 2014,sug-gesting complex effects of biotic and abiotic factors.The mean nectar volume per flower was not related to inflorescence size(the num-ber of total flowers per plant).Furthermore,nectar production was weakly associated with floral attractive traits(the petal width and the galea height),even if the effect of flowering time of individuals was removed,suggesting that the honesty of floral traits as signals of nec-tar reward for pollinators is not stable in this species.展开更多
The architectural development of Acacia karroo conforms to Troll’s model. Growth of the branches is modular and sympodial with heteroblastic leaves on all long shoots of the tree, including the seedling. Axillary bud...The architectural development of Acacia karroo conforms to Troll’s model. Growth of the branches is modular and sympodial with heteroblastic leaves on all long shoots of the tree, including the seedling. Axillary buds tend to proliferate especially on flowering shoots where they form fascicles consisting of up to 10 inflorescences arranged in two parallel serial rows per leaf axil. Most axillary buds are sylleptic and basal buds which give rise to short shoots, each producing two to five cataphylls each season, but no flowers. Inflorescences are only produced on long shoots (modules) of the current season. After flowering the terminal part of the module aborts, trees are usually andromonoecious with capitate inflorescences containing 40 to 100 flowers each, with some male and some hermaphrodite. Some trees produce only male flowers. Anthesis in the same inflorescence, the same tree as well as amongst trees of the same community are synchronised and occur at intermittent intervals, each lasting three or more days at a time. Flowers are protogynous and pollen is produced in polyads, each consisting of 16 pollen grains. Ovaries contain 10 to 14 ovules each. The concave stigma has space for only one polyad which can fertilise all ovules in the ovary after a single pollination event. Fruit set is low with 0 to 10 fruits (pods) per inflorescence.展开更多
Sex differences in morphology provide key information for understanding a species'morphological adaptations in relation to the evolution of sexual selection.In migratory birds,morphological traits have adapted to ...Sex differences in morphology provide key information for understanding a species'morphological adaptations in relation to the evolution of sexual selection.In migratory birds,morphological traits have adapted to long-distance travel,and sexual dimorphism is typically related to sex-differential migration phenology.Little Buntings(Emberiza pusilla)have one of the longest migrations and are the least dichromatic species among the Emberiza buntings.In this study,we measured sexual size dimorphism and sexual dichromatism of Little Buntings in relation to the spring arrival dates at a stopover site in Korea.Wing length was the most important predictor for identifying sex;the wings of males were longer than those of females.Males also had a significantly stronger chestnut color of the head feathers than females,but this color difference was more prominent in the spring than in the fall.Males arrived earlier than females by four days.Arrival dates correlated with both size and color,but unlike other bunting species previously studied in the same area,there was no clear sex-differential trend in the relationship between arrival date and morphological characteristics.Seasonal differences in the degree of sexual dichromatism suggest that chestnut plumage coloration can be used as a social or sexual signal of males in the breeding season.The correlation of size and color to early arrival regardless of sex may indicate that a preference for assortative mating exists or that a sex-differential migration strategy is not clearly defined in the early stages of northward migration.Our findings on the sexual dimorphism of Little Buntings provide insight into the evolution of the sex-differential migration of buntings in the East Asian Flyway.展开更多
基金Natural Science Foundation of Gansu Province(145RJZA166)Natural Science Foundation of China(30900162,31370402)Fundamental Research Funds for the Central Universities(lzujbky-2013-102).
文摘Aims Floral nectar plays a vital role in plant reproductive success by attracting pollinators.Nectar traits of a flower can depend directly on plant characteristics other than environmental factors and exhibit extensive flower-and plant-level variations.studies on nectar traits frequently focused on intraplant variation for dichogamous plants,but few have paid attention to both intra-and interplant nectar variations in relation to plant characteristics.revealing within-and among-plant variation and its relative magnitude is important for our understanding of how pollinator-mediated selection can act on nectar traits and evolution of nectar traits.Methods Through investigating protandrous Aconitum gymnandrum populations at the alpine meadows and Wetland Ecosystems research station of lanzhou university,we examined the relationships between nectar production per flower and plant characteristics(e.g.flower position within inflorescences,flo-ral sexual phases,flowering time,inflorescence size and floral attractive traits).Important Findings A.gymnandrum exhibited a declining gradient in the nectar volume along inflorescences,with more nectar in basal flowers than distal ones.Protandrous flowers of A.gymnandrum did not show gender-biased nectar production while the nectar volume varied with differ-ent stages of floral sexual phases.The significant correlation between the first flowering date of individuals and the mean nectar volume per flower was positive in 2013,but became negative in 2014,sug-gesting complex effects of biotic and abiotic factors.The mean nectar volume per flower was not related to inflorescence size(the num-ber of total flowers per plant).Furthermore,nectar production was weakly associated with floral attractive traits(the petal width and the galea height),even if the effect of flowering time of individuals was removed,suggesting that the honesty of floral traits as signals of nec-tar reward for pollinators is not stable in this species.
文摘The architectural development of Acacia karroo conforms to Troll’s model. Growth of the branches is modular and sympodial with heteroblastic leaves on all long shoots of the tree, including the seedling. Axillary buds tend to proliferate especially on flowering shoots where they form fascicles consisting of up to 10 inflorescences arranged in two parallel serial rows per leaf axil. Most axillary buds are sylleptic and basal buds which give rise to short shoots, each producing two to five cataphylls each season, but no flowers. Inflorescences are only produced on long shoots (modules) of the current season. After flowering the terminal part of the module aborts, trees are usually andromonoecious with capitate inflorescences containing 40 to 100 flowers each, with some male and some hermaphrodite. Some trees produce only male flowers. Anthesis in the same inflorescence, the same tree as well as amongst trees of the same community are synchronised and occur at intermittent intervals, each lasting three or more days at a time. Flowers are protogynous and pollen is produced in polyads, each consisting of 16 pollen grains. Ovaries contain 10 to 14 ovules each. The concave stigma has space for only one polyad which can fertilise all ovules in the ovary after a single pollination event. Fruit set is low with 0 to 10 fruits (pods) per inflorescence.
基金supported by the New Faculty Startup Fund from Seoul National University (Grant No.500-20200268)supported by the National Research Foundation of Korea (NRF) grants funded by the Republic of Korea Government (Ministry of EducationNRF2018R1D1A1B07050135 & NRF-2019R1I1A1A01063760)
文摘Sex differences in morphology provide key information for understanding a species'morphological adaptations in relation to the evolution of sexual selection.In migratory birds,morphological traits have adapted to long-distance travel,and sexual dimorphism is typically related to sex-differential migration phenology.Little Buntings(Emberiza pusilla)have one of the longest migrations and are the least dichromatic species among the Emberiza buntings.In this study,we measured sexual size dimorphism and sexual dichromatism of Little Buntings in relation to the spring arrival dates at a stopover site in Korea.Wing length was the most important predictor for identifying sex;the wings of males were longer than those of females.Males also had a significantly stronger chestnut color of the head feathers than females,but this color difference was more prominent in the spring than in the fall.Males arrived earlier than females by four days.Arrival dates correlated with both size and color,but unlike other bunting species previously studied in the same area,there was no clear sex-differential trend in the relationship between arrival date and morphological characteristics.Seasonal differences in the degree of sexual dichromatism suggest that chestnut plumage coloration can be used as a social or sexual signal of males in the breeding season.The correlation of size and color to early arrival regardless of sex may indicate that a preference for assortative mating exists or that a sex-differential migration strategy is not clearly defined in the early stages of northward migration.Our findings on the sexual dimorphism of Little Buntings provide insight into the evolution of the sex-differential migration of buntings in the East Asian Flyway.
