Institutional Repository of Xishuangbanna Tropical Botanical Garden
| ECOLOGY AND EVOLUTION OF REPRODUCTION IN MILKWEEDS | |
| WYATT, R; BROYLES, SB | |
| 1994 | |
| Source Publication | ANNUAL REVIEW OF ECOLOGY AND SYSTEMATICS
 |
| ISSN | 0066-4162 |
| Volume | 25Issue:xPages:423-441 |
| Abstract | Asclepiadaceae are the dicot counterparts to the Orchidaceae, which also transmit their pollen grains in large groups within pollinia. Unlike many terrestrial, nectar-producing orchids, however, milkweeds are characterized by low fruit-set, typically averaging 1-5%. Transfer of hundreds of pollen grains as a unit makes it possible to quantify pollinator activity and male and female reproductive success more directly and more easily in milkweeds than in plants with loose pollen grains. It also leads to the production of fruits whose seeds all share a single father, thus simplifying paternity analysis. Recent anatomical work has demonstrated that three of the five stigmatic chambers of milkweed flowers transmit pollen tubes to one of the two separate ovaries, whereas the other two chambers transmit only to the second ovary. Milkweed flowers are long-lived and produce copious nectar, which flows from nectaries within the stigmatic chambers to fill the hoods, which serve as reservoirs. Nectar also serves as the germination fluid for pollen grains, but concentrations above 30% inhibit germination. Most milkweeds are genetically self-incompatible and express an unusual late-acting form of ovarian rejection. Some weedy milkweeds, however, are self-compatible, and levels of self-insertion of pollinia are apparently high in these, as well as in self-incompatible, species. Early attempts to explain the evolution of inflorescence size in milkweeds were hampered by failure to consider the genetic basis of the variation observed and by failure to determine the unit on which selection should act. Direct tests of the ''pollen donation'' hypothesis have cast doubt on the validity of the view that flower number and other floral traits evolved primarily to enhance male reproductive success. Milkweeds are pollinated by a diverse array of large bees, wasps, and butterflies, and these generalist pollinators effect extensive gene flow within and between populations, augmented by wind dispersal of comose seeds. Morphological and biochemical evidence support the view that limited, localized hybridization occurs between sympatric species of milkweeds. |
| Keyword | Asclepias-syriaca-l North-american Asclepias Common Milkweed Nectar Production Inflorescence Size Fruit-set Natural-population Dispersal Ability Sexual Selection Exaltata |
| Language | 英语 |
| Document Type | 期刊论文 |
| Identifier | https://ir.xtbg.ac.cn/handle/353005/9156 |
| Collection | 文献共享 |
| Recommended Citation GB/T 7714 | WYATT, R,BROYLES, SB. ECOLOGY AND EVOLUTION OF REPRODUCTION IN MILKWEEDS[J]. ANNUAL REVIEW OF ECOLOGY AND SYSTEMATICS,1994,25(x):423-441. |
| APA | WYATT, R,&BROYLES, SB.(1994).ECOLOGY AND EVOLUTION OF REPRODUCTION IN MILKWEEDS.ANNUAL REVIEW OF ECOLOGY AND SYSTEMATICS,25(x),423-441. |
| MLA | WYATT, R,et al."ECOLOGY AND EVOLUTION OF REPRODUCTION IN MILKWEEDS".ANNUAL REVIEW OF ECOLOGY AND SYSTEMATICS 25.x(1994):423-441. |
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| Ecology and Evolutio（1577KB） | 开放获取 | CC BY-NC-SA | View Download | |||
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