綜合分子與食性證據探討黃蝶的多樣性問題

Utility of COI and COII genes on the systematics of Eurema hecabe complex and interpretations in their host-plant associations

莊玉筵(Chuang Yu-Yen)

指導教授 ： 徐堉峰

國立臺灣師範大學/理學院/生命科學研究所/碩士(2005年)

摘要

黃蝶(Eurema hecabe)由於為昆蟲中著名的研究物種之一，個體的形態受到照光週期、溫度高低等因素的影響，表現出高度的多樣性，在眾多昆蟲中常作為多表現型(polyphenism)的典型範例。黃蝶的食性廣泛，可利用豆科(Fabaceae)、大戟科(Euphorbiaceae)、鼠李科（Rhamnaceae）等植物，與食性有關連的族群可能會形成host race，而被認為同域種化的中間步驟。本研究綜合粒線體COI及COII基因與食性交換實驗探討在利用不同寄主植物的黃蝶族群之食性演化。所要解決的問題包括：（1）各型黃蝶是否各形成單系群？（2）替換各型黃蝶的寄主植物，其幼蟲存活率為何？（3）檢視各型黃蝶標本，緣毛形態是否有差異？ MP樹與ML樹中，大戟科族群形成一個單系群（bootstraps值80；貝氏支持度=0.97），而豆科型與鼠李科型則無法解析，推斷分化時間較大戟科型族群早，利用豆科與鼠李科可能為祖徵，大戟科為衍生而來。食性交換顯示三型黃蝶對寄主植物的忠誠度高，除了大戟科可以利用豆科外，其他無法替代利用，幼蟲全數死亡。根據緣毛形態，豆科型(n=70)與鼠李科型(n=30)分別與Kato(1992)所定義的褐色型與黃色型相同，大戟科型標本中，有68%(n=44)顏色分佈呈現黃色寬帶搭配褐色窄帶的情形，為其他兩型未見。此結果顯示大戟科型族群為獨立的一群，豆科型族群與鼠李科型族群可能分化時間相對大戟科型族群較早，也可能仍有基因交流，使得此片段的資料無法解析。黃蝶的食性利用確有分化情形，三型族群分別屬於不同的host race，而分化程度則考慮未來能輔以生態資料分析其基因交流的可能性及程度。

關鍵字

黃蝶 ； 遺傳多型性 ； 種分化

並列摘要

Eurema hecabe has been frequently cited as an ideal example of polyphenism due to photoperiod, temperature, or the other factors. Larval host-plant of Eurema hecabe in Taiwan include Fabaceae, Euphorbiaceae, and Rhamnaceae which may formed so-call host races. And Diehl & Bush (1984) recognized the host races as an important intermediate step toward sympatric speciation. According to larval hosts, three types of Eurema hecabe were recognized, namely, Fabaceae type, Euphorbiaceae type, and Rhamnaceae type. In this study, we intend to investigate the direction of evolution of host usages of E. hecabe associated with different host families using coI and coII genes of mithchondrial DNA, and to perform host-switch tests to local E. hecabe populations. The questions that we ask are (1) Is each type monophyletic? (2) How are their survival rate if we change their host-plants? (3) Does any difference among their fringe color and compare with ones in Japan that presented by Kato (1992). Eup-type performed monophyly group in ML and MP trees. Neither samples of Fab-type nor Rha-type formed a clade on the tree. We inferred that the divergent time in Eup-type is much later than Fab-type and Rha-type. it’s higher probability that larval using Fabaceae plant is a ancestral character. Larval using Rhamnaceae and Euphorbiaceae is derived character. Using Fisher’s exect test that Fab-type and Rha-type performed highly fidelity in their natural host, however they could not use other plant and all died. Eup-type performed highly fidelity not only in natural host but tested with Fabaceae. In fringe color Fab-type(n=70) and Rha-type(n=30) performed the same type that presented by Kato(1992). But in Eup-type, there were different color type interlacing wide brown and narrow yellow zone(n=44).
In conclusion, Euphorbiaceae type is a unique group. It was required that host formation in E. hecabe is host-shifts and higher preference for their natal hosts.

並列關鍵字

Eurema hecabe ； polyphensim ； speciation