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.