根據(jù)所給中文完成句子：
The _____ observation, of the absence of grazers （食草動物）in areas of high phytoPlankton（浮游植物群落）_______, led Hardy to propose his principle of animal _______ , which _______ that phytoplankton produced a repellent（驅(qū)蟲劑） that excluded grazers from regions of high phytoplankton concentration.
[參考譯文]
相反的觀察，即在浮游植物群落高度集中的地方缺乏食草動物的現(xiàn)象，使哈笛提出了他的"動物排除"理論，該理論假設(shè)浮游植物群落能產(chǎn)生一種驅(qū)蟲劑趕走在浮游植物高度集中區(qū)域內(nèi)的食草動物。
The _____ observation, of the absence of grazers （食草動物）in areas of high phytoPlankton（浮游植物群落）_______, led Hardy to propose his principle of animal _______ , which _______ that phytoplankton produced a repellent（驅(qū)蟲劑） that excluded grazers from regions of high phytoplankton concentration.
[參考譯文]
相反的觀察，即在浮游植物群落高度集中的地方缺乏食草動物的現(xiàn)象，使哈笛提出了他的"動物排除"理論，該理論假設(shè)浮游植物群落能產(chǎn)生一種驅(qū)蟲劑趕走在浮游植物高度集中區(qū)域內(nèi)的食草動物。