與大多數其他生物一樣，昆蟲的多樣性在熱帶區域較溫帶區域為高，然而熱帶各區域之間的標準化比較研究相當稀少。要解開影響群聚多樣性的生態，演化與生物地理因子需要標準化的作業流程和長期研究。作者在低地雨林鬱閉樹冠的底層以Pollard walk穿越線計數法比較巴拿馬的巴羅科羅拉多島(BCI)，泰國的拷秋(KHC)與新幾內亞的瓦那(WAN)共三個地點的蝴蝶豐富度和多樣性。作者在上述三地分別以231、231、120次穿越線調查，觀察到1792、 2797、 3331隻蝴蝶個體，各有128、 131、134個物種。分別對穿越線長度和調查時間長度進行數據校正後，結果顯示蝴蝶數量與物種豐富度分別在WAN和KHC最高。雖然在WAN的蝴蝶豐富度看來似乎並非由於人工方法所造成，此觀察的生物學上意義仍然是模糊的。WAN地區的植物多樣性與KHC相當，但是所擁有的蝴蝶霧種多樣性卻較KHC低。此現象強調了在植物多樣性之外的因素，例如生物地理歷史，對於解釋造成蝶類多樣性的成因的重要性。KHC特別多樣的蝴蝶相可能是由於其地理位置位在印度中國區和巽它大陸區的交會點。相反的，WAN則穩固位在澳洲地理區，且其較低的物種多樣性可能導因自島嶼生物地理過程。這三個地點的常見物種皆有幾個特色：食果和食蜜者平均出現，超過一半的常見種幼蟲時期取食附生植物或藤蔓類，且他們的翅長近似。由這些觀察推測， Pollard walk穿越線計數法在不同的熱帶雨林樣區指出了常見種的相似集合，並且是一個熱帶雨林蝴蝶組成長期監測的有用工具。
Abstract. Insects, like most other organisms, are more diverse in tropical than in temperate regions, but standardized comparisons of diversity among tropical regions are rare. Disentangling the effects of ecological, evolutionary, and biogeographic factors on community diversity requires standardized protocols and long-term studies. We compared the abundance and diversity of butterflies using standardised ‘Pollard walk’ transect counts in the understory of closed-canopy lowland rainforests in Panama (Barro Colorado Island, BCI), Thailand (Khao Chong, KHC) and Papua New Guinea (Wanang, WAN). We observed 1792, 1797 and 3331 butterflies representing 128, 131 and 134 species during 230, 231 and 120 transects at BCI, KHC and WAN, respectively. When corrected for length and duration of transects, butterfly abundance and species richness were highest at WAN and KHC, respectively. Although high butterfly abundance at WAN did not appear to result from methodological artefacts, the biological meaning of this observation remains obscure. The WAN site appeared as floristically diverse as KHC, but supported lower butterfly diversity. This emphasizes that factors other than plant diversity, such as biogeographic history, may be crucial for explaining butterfly diversity. The KHC butterfly fauna may be unusually species rich because the site is at a biogeographic crossroads between the Indochinese and Sundaland regions. In contrast, WAN is firmly within the Australian biogeographic region and relatively low species numbers may result from island biogeographic processes. The common species at each of the three sites shared several traits: fruit and nectar feeders were equally represented, more than half of common species fed on either epiphytes or lianas as larvae, and their range in wing sizes was similar. These observations suggest that Pollard walks in different tropical rainforests target similar assemblages of common species, and, hence, represent a useful tool for long-term monitoring of rainforest butterfly assemblages.
Keywords: Barro Colorado Island, Center for Tropical Forest Science, Lepidoptera, tropical rainforest, Panama, Papua New Guinea, Pollard walks, Smithsonian Institution Global Earth Observatories, Thailand.
Received: 22 December 2010
Accepted: 24 January 2011
Published online at www.lepidopteraresearchfoundation.org on 4 May 2011