Olsen Kenneth M
Department of Biology, Box 1137, Washington University, 1 Brookings Drive, St. Louis, MO 63130-4899, USA fax: (314) 935-4432, , , , , , US.
Oecologia. 1996 Dec;109(1):114-121. doi: 10.1007/PL00008811.
Assessing the relative contributions to seed set for each of a plant species' floral visitors provides an indication of the relative influence of these visitors on the plant's reproductive success. This study examined pollinator activity and seed set in a population of Heterotheca subaxillaris, a species that exhibits a floret dimorphism (heads bearing disk and ray florets), and that is visited by both generalist foragers and specialist bees. Visits by nine bee genera and one genus of skipper were recorded in the study population. During the period of study, these insects varied in their relative abundance, in their foraging activity on a head, and in their pollination effectiveness. The pattern of pollination effectiveness shown by the different pollinators was similar for both floret types, although seed set was higher overall for ray florets. Pollinator importance, calculated as the product of pollination effectiveness and relative abundance, was dictated by a pollinator's relative abundance. The single specialist bee species observed in the study population proved to have neither higher pollination effectiveness nor higher pollinator abundance than other pollinators. This would suggest that H. subaxillaris is not under strong selective pressure to co-specialize with its specialist visitor.
评估某一植物物种的各类访花者对结实率的相对贡献，可表明这些访花者对该植物繁殖成功的相对影响。本研究调查了腋生异果菊种群中的传粉者活动和结实率，腋生异果菊具有小花二态性（头状花序上有盘花和舌状花），且有泛食性觅食者和专性蜜蜂访花。研究种群中记录了9个蜜蜂属和1个弄蝶属的访花情况。在研究期间，这些昆虫在相对丰度、在头状花序上的觅食活动以及授粉效率方面存在差异。尽管舌状花的总体结实率更高，但不同传粉者表现出的授粉效率模式在两种小花类型中相似。授粉者重要性以授粉效率和相对丰度的乘积计算，由授粉者的相对丰度决定。在研究种群中观察到的单一专性蜜蜂物种，其授粉效率和授粉者丰度并不高于其他传粉者。这表明腋生异果菊在与专性访花者共同特化方面并未受到强烈的选择压力。
