高效视觉和触觉刺激对无尾类蝌蚪生长和变态的影响.doc

國立台灣大學生態學與演化生物學研究所碩、博士專題討論摘要 日期：2006年6月16日題目：視覺和觸覺刺激對無尾類蝌蚪生長和變態的影響作者：Rot-Nikcevic, I., R. J. Denver and R. J. Wasstersug出處：Functional Ecology (2005) 19: 1008-1016講者：官淑蕙指導老師：林雨德 助理教授摘要：蝌蚪能藉由嗅覺、視覺和觸覺線索偵測環境狀況，並對此做出適當的反應。然而前人研究多著重在嗅覺線索方面，鮮少有視覺和觸覺的相關研究，因此Rot-Nikcevic等人做了一系列有關視覺和觸覺如何影響蝌蚪生長發育的實驗。在2005年利用三種蝌蚪（木蛙Rana、美洲蟾蜍Bufo和非洲爪蟾Xenopus）進行實驗，將相同數量的假黏土蝌蚪置於蝌蚪群中，模擬自然界中同種密度增加的情況，以測試不同蝌蚪分別對視覺、觸覺或兩者合併之線索產生的反應。結果發現木蛙蝌蚪（Rana）對於視覺和觸覺合併線索的反應最強烈，非洲爪蟾次之而美洲蟾蜍反應最小；當木蛙蝌蚪同時處於兩種線索刺激下，會提早並以較小的體型變態，再者體內壓力激素-皮質酮（corticosterone）含量亦會升高，推測此為提早變態之原因。而2006年則以二種蝌蚪（木蛙Rana和美洲蟾蜍Bufo）進行實驗，將鏡子置於飼養箱壁上經由反射影像模擬同種密度增加，另外更增設實際密度增加組（蝌蚪數量加倍），以測試不同種蝌蚪的對視覺線索的反應。結果與2005年相似，無論實際密度增加組或鏡子模擬組，木蛙蝌蚪（Rana）的反應最強烈，在此刺激下會使其較晚且以較小的體型變態，同時會增加每日的活動量；相反地，美洲蟾蜍（Bufo）僅在實際密度增加時（蝌蚪數量加倍）才會改變其生長發育速率，而對鏡子所造成的視覺線索並無明顯反應。由上述結果可知：蝌蚪的確會利用視覺和觸覺來偵測分析環境的變化，並反應在生長發育（變態時間）、激素和活動量的改變，藉此逃離不良或不適合之環境；此外，不同物種間對於視覺和觸覺線索的反應亦不同，可能是因不同種蝌蚪在野外有各自不同程度的群聚行為和群族密度所致。參考文獻：Rot-Nikcevic, I., C. N. Taylor and R. J. Wassersug. 2006. The role of images of conspecifics as visual cues in the development and behavior of larval anurans. Behavioral Ecology and Sociobiology 60: 19-25.Shi, Y.-B. 2000. Amphibian metamorphosis: from morphology to molecular biology. John Wiley & Sons, Inc., Toronto.Topic:The influence of visual and tactile stimulation on growth and metamorphosis in anuran larvae.Authors:Rot-Nikcevic, I., R. J. Denver and R. J. WasstersugJournal:Functional Ecology (2005) 19: 1008-1016Speaker:Su-Hwei GuanAdvisorAbstract:Dr. Yu-Teh LinThe authors do a series of experiments about the role of visual and tactile cues in anuran larvae, and they want to determine whether visual or tactile cues in the absence of chemical signals influenced the growth, development, stress hormone and activity of tadpoles. First, they put “clay model tadpoles” into the tanks with live tadpoles that enhance visual and tactile stimuli for tadpoles of three species (Rana sylvatica, Bufo americanus and Xenopus laevis) in 2005. The response to enhanced visual and tactile stimuli in first experiment was strong in Rana, intermediate in Xenopus, but absent in Bufo tadpoles. Rana tadpoles that experienced both stimuli enhanced metamorphosed earliest at the smallest body size and showed the highest whole-body content of the stress hormone corticosterone, suggesting that the enhanced stimuli were experienced as stressful. Development was slower in the treatments with only one stimulus enhanced, and slowest in the controls. And further, they raised Rana sylvatica and Bufo americanus tadpoles in the tanks with mirrors to simulate the increased density and to enhance visual stimulus in 2006. Both physically increased density and increased density simulated with mirrors made Rana tadpoles metamorphosing later at the smaller body size and increasing activity while only true increased density had an effect on growth and activity in Bufo tadpoles. These results suggest that tadpoles can use both vision and taction for environment assessment, and they are able to modify their growth, development and activities by changing stress hormone in response to sensory enrichment. The response is species-specific because of their different school behaviors and population densities in the wild.Reference:Rot-Nikcevic, I., C. N. Taylor and R. J. Wassersug. 2006. The role of images of conspecifics as visual cues in the development and behavior of