台灣產姬春蟬屬之親緣關係及其幅射適應與鳴聲探討

Abstract

在台灣產的蟬中姬春蟬屬(Euterpnosia)是種類最多的一屬，全世界已記錄25種，在台灣有16種，皆為特有種。由外部形態所建立的的親源關係樹來看本屬應為單系群，其中阿里山姬春蟬(Euterpnosia arisana Kato, 1925)、水社姬春蟬(Euterpnosia suishana Kato, 1930)及寬尾姬春蟬(Euterpnosia latacauta Kato, 2008)為一多分枝的姐妹群，多分枝為快速幅射演化的一個重要特徵。鳴聲分析主要分析招喚聲，雄蟬鳴叫吸引雌來交尾，這是性選汰中的雌蟲選擇，這是一個極強的選汰力量。從波形圖分析來看，姬春蟬的波形差異頗大，可以當做良好的鑑定特徵;從音頻圖分析來看，姬春蟬的音頻約在0-20kHz之間，通常會有二段強頻帶，第1強頻帶約在5-10kHz間，第2強頻帶約在10-17kHz間。鳴聲的改變在姬春蟬的生殖隔離上扮演重要角色，從觀霧產的太平姬春蟬(Euterpnosia varicolor Kato, 1926)及高山姬春蟬(Euterpnosia alpina Kato, 2005)所產生的鳴聲性狀替換效應來看，二種雄蟬都將音頻提高，這是為了加強交配前的隔離所做的改變，這證明鳴聲對這二種姬春蟬都不是很強的生殖隔離，鳴聲屬於低分化這也是快速幅射演化的特徵。在花東地區的高士佛姬春蟬(Euterpnosia olivacea Kato, 1927)，廣泛分布於台灣東部，從屏東壽卡到花蓮太魯閣，各族群間在尾節(生殖器)內側緣片可以看出漸進的變化，最南的族群與最北的族群幾乎已是不同的二個種，這應是地理區隔所產生的族群差異。從親源關係、鳴聲及族群間的差異來看，姬春蟬屬符合幅射適應理論。

Among Euterpnosia genus is the most species genus among Taiwan’s cicadas, 25 species described worldwide, sixteen Euterpnosia species have been recorded in Taiwan, all endemic to Taiwan. This genus is a monophyletic group based on cladistic analysis of morphological data. Analysis demonstrates that the Euterpnosia tree contains a basal polytomy of sister group(E. arisana, E. suishana and E. latacauta) that indicates a rapid radiation. The calling songs produced by males are generally thought to be species-specific, and can be used as a species specific taxonomic character, which is a female choice in sexual selection. Acoustic analysis indicated that the spectrogram of frequence of Euterpnosia are approximately 0-20 kHz with two dominant frequency bandwidths, 1 st dominant frequency bandwidth is approximately 5-10kHz，2 nd dominant frequency bandwidth is approximately 10-17kHz. Acoustic changes might have contributed to reproductive isolation, E. varicolor and E. alpina indicated the character displcement of calling song is an illustration in Guanwu, both its dominant frequency increased for premating isolation. It demonstrates that low divergence in calling song for rapid radiation. E. olivacea is a widespread species in the Eastern Taiwan from Shouka to Tailuge. Inward lobe of E. olivacea of every population form gradual changes, and E. olivacea of Shouka and E. olivacea of Tailuge may be different species. Variation of E. olivacea might be produced by geographical barriers. Phylogeny, acoustic behaviour and population of variations of the genus Euterpnosia seems to display adaptive radiation in Taiwan.