種化是由寄主驅動還是地理隔絕？以DNA條碼進行生態群聚間的族群遺傳比較

文獻來源：KJ Craft, SU Pauls, K Darrow, SE Miller, PDN Hebert,, LE Helgen, V Novotny, GD Weiblen. 2010. Population genetics of ecological communities with DNA barcodes: An example from New Guinea Lepidoptera. Proceedings of the National Academy of Science 107(11):5041-5046.

對生態上同功群的比較族群遺傳結構可反映出關於群聚多樣性的起源與維持之差異模式的通性。新幾內亞與美洲的熱帶鱗翅目寄主專一性與生態系間物種多樣性之間矛 盾的評估，已點燃了解釋多樣性隨緯度呈梯度變化之爭論：是由寄主植物互動造成分化？或是地理隔絕？作者由新幾內亞的八個地點與分屬於四個屬的寄主植物上選 取28種鱗翅目昆蟲，對共計1359個個體選取粒線體COI基因進行基因型分析，並評估族群分化與寄主植物和地理之關係。分子差異與基因型網狀分析顯示生 態上相似的同域物種其遺傳結構樣式有變化。有四分之一缺乏距離隔離或寄主互動造成的變異，但也有21%兩者兼具。14%的物種存有寄主互動造成的變異但不 具地理隔絕，而18%的物種則正好相反，另外21%的結果則模稜兩可，故目前結果看來，分子差異與基因型網狀分析得到的是 不相容的結果。群聚成員之間食性寬廣度的差異推測食性專一所造成的種化機制是重要的，但對熱帶鱗翅目的分化而言並非是普遍通行的。而地理廣 布的基因型則挑戰了割據生物地理學的預測。播遷是重要的，而鱗翅目的群聚則隨其組成物種的不同親緣地理歷史表現出頗高的動態變化。主要熱帶區與溫帶區的草 食者之間的族群遺傳仍有待測試其生態學理論和評估全球生物多樣性樣式之預測。

Comparative population genetics of ecological guilds can reveal generalities in patterns of differentiation bearing on hypotheses regarding the origin and maintenance of community diversity. Contradictory estimates of host specificity and beta diversity in tropical Lepidoptera (moths and butterflies) from New Guinea and the Americas have sparked debate on the role of host-associated divergence and geographic isolation in explaining latitudinal diversity gradients. We sampled haplotypes of mitochondrial cytochrome c oxidase I from 28 Lepidoptera species and 1,359 individuals across four host plant genera and eight sites in New Guinea to estimate population divergence in relation to host specificity and geography. Analyses of molecular variance and haplotype networks indicate varying patterns of genetic structure among ecologically similar sympatric species. One-quarter lacked evidence of isolation by distance or host-associated differentiation, whereas 21% exhibited both. Fourteen percent of the species exhibited host-associated differentiation without geographic isolation, 18% showed the opposite, and 21% were equivocal, insofar as analyses of molecular variance and haplotype networks yielded incongruent patterns. Variation in dietary breadth among community members suggests that speciation by specialization is an important, but not universal, mechanism for diversification of tropical Lepidoptera. Geographically widespread haplotypes challenge predictions of vicariance biogeography. Dispersal is important, and Lepidoptera communities appear to be highly dynamic according to the various phylogeographic histories of component species. Population genetic comparisons among herbivores of major tropical and temperate regions are needed to test predictions of ecological theory and evaluate global patterns of biodiversity.

印度那加蘭地區野生天蠶蛾類的多樣性與生態學

Diversity and ecology of wild sericigenous insects in Nagaland, India.

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文獻來源: LN Kakati & BC Chutia. 2009. Diversity and ecology of wild sericigenous insects in Nagaland, India. Tropical Ecology 50(1): 137-146

Abstract: This paper deals with the diversity of wild sericigenous insects i.e., silk producing moths in Nagaland, a small mountainous state of north eastern India. A periodic survey conducted during 2004-2006 revealed the presence of 14 species belonging to 8 genera i.e. Antheraea, Actias, Attacus, Archaeoattacus, Cricula, Loepa, Samia, Sonthonnaxia and a large number of host plants. However, only four species are commercially exploited in Nagaland at present and there remains a great scope for producing novel silk from Actias selene, Antheraea roylei, Samia canningi and Cricula trifenestrata. The egg, worm, cocoon and adult stages of certain species have been studied for character evaluation and categorization. The paper emphasizes the importance of these lesser known silk producing insects, causal factors for depletion of population density and advocates for great need for conservation of wild silk moths and their ecological environment in Nagaland. Further, the paper highlights the socioeconomic perspective of rearing and utilizing wild silk moths by the forest dwelling tribal people who could play a major role in conserving these insects and their habitats.

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?

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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.