台灣兩種近緣溪樹蛙在交界帶的聲音訊號辨識與遺傳交流

Acoustic signal discrimination and potential gene flow between two sibling Buergeria tree frogs across the contact zones in Taiwan

蕭郁薇(Hsiao Yu-Wei)

指導教授 ： 林思民

國立臺灣師範大學/理學院/生命科學系/碩士(2018年)

https://doi.org/10.6345/THE.NTNU.SLS.010.2018.D01

摘要

物種分布的交界帶就像一個天然的演化實驗室。從生態的觀點來看，此處提供了研究物種間互動的機會，包括：資源區分、種間競爭、訊息辨識與傳遞等等；另一方面，近緣種之間的分化時常伴隨遺傳交流，小尺度的交界帶也提供了檢測遺傳滲入方向與程度的機會。日本樹蛙(B. japonica)與太田樹蛙(B. otai)是溪樹蛙屬(Buergeria)中的姊妹物種，兩者使用的棲位相似，但分布地區有所差異：日本樹蛙分布於台灣西北部，太田樹蛙則分布於東部及西南部，在台灣東部的宜蘭和西部的嘉義各形成一個交界帶。兩者總共使用三種長鳴叫作為求偶訊息：共同使用的第一型叫聲(Type 1a和Type 1b)與太田樹蛙使用的獨特叫聲(Type 2)。在這個研究中，我們欲探討鳴叫聲辨識是否具有阻隔遺傳交流的效果。我們在最靠近交界帶的地方選取四個族群進行回播實驗，檢視兩物種的雄性個體對於三種聲音的反應，結果顯示兩種溪樹蛙皆對同種叫聲的反應較強，對異種訊息的反應程度低，呈現對稱的反應結果，雄性對分歧訊號的辨別能力暗示了物種之間能夠辨識彼此訊號的能力。遺傳交流以限制酶點位標定法(RAD-seq)取得的大量序列檢測，在親緣關係樹以及STRUCTURE歸群檢測中沒有發現近期的遺傳交流事件，但透過G-PhoCS則檢測出東西部交界帶均發生由日本樹蛙滲入太田樹蛙的歷史事件。遺傳與行為的檢測結果一致，暗示了兩個物種之間的訊號辨識能力能夠阻隔近期的遺傳交流。

關鍵字

物種辨識 ； 行為對稱反應 ； 限制酶點位標定 ； 遺傳滲入

並列摘要

Contact zones between sibling species are nature laboratories for evolutionary and ecological studies. In the genetic view, contact zones provide a good place to exam the genetic integrity of species. In the ecological view, the competition, communication and interaction between species were well studied in acoustic-communicated species such as frogs, birds, and some insects. The signal discrimination between two species is crucial to communication and species recognition, which may affect species fitness directly (female choice) or indirectly (male discrimination). Buergeria japonica and B. otai are sister species which use similar niche and communication signals. In Taiwan, they distribute in different drainages, forming two narrow contact zones in eastern (Yilan) and western (Jiayi) Taiwan. The acoustic signals they use include sharing long call (Type 1a of B. japonica and Type 1b of B. otai) and a unique long call (Type 2) of B. otai. In this study, I aim to test whether the divergence of acoustic signal plays a role on the barrier of gene flow. I conducted playback experiment to males both species to exam their response toward conspecific and heterospecific signals. The result shows symmetric result that both species response more to conspecific long call, implying their correct species recognition. In the test of gene flow, I obtained genome-wide SNPs by using RAD-seq. The assignment test showed no recent gene flow between two species, although ancient introgressions from B. japonica to B. otai in both contact zones were detected. The consistent results between genetic and behavioral experiments suggest that the discrimination of acoustic signal functions as a barrier of recent gene flow.

並列關鍵字

male discrimination ； symmetric response ； multiple shotgun genotyping (MSG) ； genetic introgression

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