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| photo from Fig. 1 |
摘要
Both cryptic and aposematic colour patterns can reduce predation risk to prey. These distinct strategies may not be mutually exclusive, because the impact of prey coloration depends on a predator's sensory system and cognition and on the environmental background. Determining whether prey signals are cryptic or aposematic is a prerequisite for understanding the ecological and evolutionary implications of predator–prey interactions. This study investigates whether coloration and pattern in an exceptionally polymorphic toad, Rhinella alata, from Barro Colorado Island, Panama reduces predation via background matching, disruptive coloration, and/or aposematic signaling. When clay model replicas of R. alata were placed on leaf litter, the model's dorsal pattern – but not its colour – affected attack rates by birds. When models were placed on white paper, patterned and unpatterned replicas had similar attack rates by birds. These results indicate that dorsal patterns in R. alata are functionally cryptic and emphasize the potential effectiveness of disruptive coloration in a vertebrate taxon.
一個生物如果牠的顏色與背景很像，我們會說這是隱蔽色；如果他的身上有些斑紋但不太明顯，或許還是隱蔽色，那麼如果身上的斑紋又更明顯，那麼這時還會覺得是隱蔽色嗎？或是這是警戒色呢？又該如何判斷呢
分佈於巴拿馬的枯葉蟾蜍(Rhinella alata)是一個有毒的多態型的物種，型態的變化可分為純色、有線條與鑽石型的斑紋，之所以會認為鑽石型的斑紋就是因為蟾蜍本身有毒（在其他的行為學實驗中，只要能將毒+斑紋產生整體認知，就會產生避免捕食的行為）。作者將類似實體的36個黏土模型（上圖）放置在野外的45條穿越線上，共1620個模型放置在落葉上，另將一樣的1008個模型放置在白紙上，比較被鳥類捕食者的攻擊率。
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| photo from Fig. 5 |
結果如上圖，若是只有純色的模型被攻擊率是統計不顯著，將斑紋+純色放在白紙上也是不顯著，甚至有斑紋的被攻擊率還比較高。但放在落葉層這個自然環境下，有斑紋的模型被攻擊率顯著降低，支持斑紋可能讓捕食者產生某種避忌的認知連結。
Wrote by Chia-Hsuan Wei
