Flowering, pollination and pollinators of mangroves in Okinawa

本研究历时3年，从2002年到2004年。主要研究地点是日本冲绳金县大久壁河入海口的红树林。在可能的情况下，每周进行定期观察和样本采集。在某些时候，特别是在2004年，台风事件使采样变得困难。木本植物流动物候全年发生一次，秋茄为一年一次。虽然木霉全年开花，但成功结果仅限于6月至12月。1-5月形成的花的花药并不总是开放的，花粉萌发能力很低，用花粉袋盖住木兰花以防止传粉者访问时，花瓣开张率不到8%。相反，在自然条件下，花瓣开张率约为94%。较大的传粉者对花的访问，如Sphex argentatus和Zosteropus Japan loo…更多的秋葵，有助于诱导花瓣充分开放，并促进花粉从花药中扩散。然而，很小的昆虫(包括飞蛾)的造花却不能帮助花瓣打开。这表明它们作为传粉者的作用并不比大型传粉者那么重要。在人工花粉袋处理下，木兰花(防止异花授粉)的花瓣开花率约为8%。在这些有限的花瓣张开中，可以辨认出一些由自花授粉引起的胚珠扩张。这表明在自然条件下自花授粉是可能的。然而，总的来说，木本植物的自花授粉率似乎很小。然而，微卫星分析的结果也表明，木本植物和秋茄的自花授粉率相对较高，这表明具有一定自花授粉能力的红树树种，如木兰和秋茄，具有更容易迁移的优势，一旦进入新的生态环境，比其他没有自花授粉能力的红树物种能够更有效地维持自己的群落。较少

The duration of this research was 3 years, 2002 to 2004. The main research sites were mangrove forests at the mouth of Okukubi River, Kin, Okinawa, Japan. Regular observations and sample collections were made when possible at weekly intervals. At times especially during 2004, typhoon events made sampling difficult. Bruguiera gymnorrhiza flowing phenology occurred throughout the year, while that of Kandelia candel was once a year. Although B.gymnorrhiza flowered throughout the year, successful fruiting was restricted to the period June to December. Anthers of flowers formed from January to May did not always open and pollen germination abilities of these flowers were very low.When flowers of B.gymnorrhiza were covered with pollen bags to prevent visits by pollinators, rates of petal opening were less than 8 %. In contrast, rates of petal opening under natural conditions were approximately 94 %. Visits to flowers by larger pollinators, such as Sphex argentatus and Zosteropus japonica loo … More chooensis, helped to induce full petal opening and enhance pollen dispersal from anthers. However, flower visiting by very small insects (including moths) such as Macroglossum mediovitta, failed to help petal opening. This suggested that their roles as pollinators were not so important compared to those of lager pollinators. Under the artificial pollen bag treatment of B.gymnorrhiza flowers (prevent cross-pollination) petal-opening rates of such flowers to disperse pollen were approximately 8 %. Within these limited petal-openings some expansions of ovules caused by the self-pollination could be recognized. This indicates that some self-pollination might be possible under natural conditions. Nevertheless, in general, it seems that self-pollination rates of woody plants are small. However, results of microsatellite analyses also suggested that relatively higher self-pollination rates can occur in B.gymnorrhiza and K.candel.Thus these results suggest that mangrove tree species having some self-pollination abilities, such as B.gymnorrhiza and K.candel, had some advantages of easier migration and, once in a new ecohabitat, are able to maintain their communities more efficiently than other mangrove species that lack these self-pollination abilities. Less