Received: 3 April 2017 | Revised: 25 May 2017 | Accepted: 30 May 2017 DOI: 10.1002/ece3.3221 ORIGINAL RESEARCH Does spatial variation in predation pressure modulate selection for aposematism? S. Tharanga Aluthwattha1,2 | Rhett D. Harrison3 | Kithsiri B. Ranawana4 | Cheng Xu5 | Ren Lai5 | Jin Chen1 1Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Abstract Garden, Chinese Academy of Sciences, It is widely believed that aposematic signals should be conspicuous, but in nature, they Mengla, Yunnan, China vary from highly conspicuous to near cryptic. Current theory, including the honest 2University of Chinese Academy of Sciences, Beijing, China signal or trade- off hypotheses of the toxicity–conspicuousness relationship, cannot 3World Agroforestry Centre, East & Southern explain why adequately toxic species vary substantially in their conspicuousness. Africa Region, Woodlands, Lusaka, Zambia Through a study of similarly toxic Danainae (Nymphalidae) butterflies and their mimics 4Department of Zoology, University of Peradeniya, Peradeniya, Sri Lanka that vary remarkably in their conspicuousness, we show that the benefits of conspicu- 5Kunming Institute of Zoology, Chinese ousness vary along a gradient of predation pressure. Highly conspicuous butterflies Academy of Sciences, Kunming, Yunnan, China experienced lower avian attack rates when background predation pressure was low, Correspondence but attack rates increased rapidly as background predation pressure increased. Jin Chen, Key Laboratory of Tropical Forest Conversely, the least conspicuous butterflies experienced higher attack rates at low Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, predation pressures, but at high predation pressures, they appeared to benefit from Mengla, Yunnan, China. crypsis. Attack rates of intermediately conspicuous butterflies remained moderate and Email:
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