2009年7月28日 星期二

授粉昆蟲是否比植食昆蟲具有更廣的食性選擇?

photo by Bettaman
Are insect pollinators more generalist than insect herbivores?
1. Colin Fontaine1,*, 2. Elisa Thebault1 and 3. Isabelle Dajoz2

Author for correspondence (c.fontaine@imperial.ac.uk).

近年來的生物群聚層次的研究已經領會到廣食性物種遠比過去所認知的還要多,而這些研究成果也突顯了這些廣食性生物在群聚功能與演化中的優勢影響力。取食與互利共生這類的交互作用被認為應該會影響物種的廣食性程度,然而目前並沒有進行直接的比較,作者在此研究中以44個植物與昆蟲間取食或傳粉的網狀關係進行比較。分析顯示交互作用的類型確實會對物種的廣食性各種面向產生影響,從群聚中廣食性的分布到與昆蟲物種有交互作用的植物親緣關係上的多樣性。然而,觀察到的改變範圍視所研究物種廣食性而定。當非量化與量化的測量暗示傳粉者與較多種植物互動且互動關係比食植者更均勻,親緣關係上的測量清楚的顯示食植者和植物物種之間的互動遠比傳粉者與植物更加緊密。此比較方法藉由指出屬於各交互作用類型的群聚所擁有的一些基本特點,為更了解多物種集合的功能與演化提供一個有希望的觀點。

Abstract

Recent community-level studies have acknowledged that generalist species are more widespread than previously thought and highlighted their preponderant impact on community functioning and evolution. It is suggested that the type of interaction, trophic versus mutualistic, should affect species generalization level; however, no direct comparison has been made yet. Here, we performed such a comparison using 44 plant–insect networks describing either pollination or herbivory communities. Our analysis shows that the type of interaction does indeed have an impact on various aspects of species generalism, from the distribution of generalism in the community to the phylogenetic diversity of the plants with which a given insect species interacts. However, the amplitude of the observed differences depends on the aspect of species generalism studied. While the non-quantitative and quantitative measures of generalism suggest that pollinators interact with more plant species and more evenly than herbivores, phylogenetic measures clearly show that herbivores interact with plant species far more closely related to each other than pollinators. This comparative approach offers a promising perspective to better understand the functioning and evolution of multispecies assemblages by pointing out some fundamental singularities of communities depending on the type of interaction considered.

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