Embryonic background risk promotes the survival of tadpoles facing surface predators

Adam L Crane,Maud C O Ferrari,Douglas P Chivers,Peter Eklöv

doi:10.1371/journal.pone.0193939

Abstract

Exposure to intense predation risk can induce morphological and behavioural phenotypes that prepare prey, often at young ages, for surviving attacks from unknown predators. However, previous studies revealed that this survival advantage depended on the predator species. Here, we used alarm cues from injured conspecifics to simulate a period of high predation risk for embryonic wood frogs, Lithobates sylvaticus. Two weeks post-hatching, we tested whether the embryonic risk exposure influenced survival in encounters with two novel predators: (1) a spider (Dolomedes sp.) that ambushes prey exclusively on the surface of the water, and (2) the adult predacious diving beetle (Dytiscus sp.) which displays underwater sit-and-wait posture and pursuit tactics. Tadpoles exposed to embryonic high-risk survived longer when encountering spiders, whereas background risk had no influence on survival with adult beetles. These findings, coupled with survival studies involving other predator types, indicate that a high-risk environment promotes tadpole survival in future encounters with unknown sit-and-wait predators, but at the cost of increased vulnerability to novel predators capable of active pursuit.

Highlights

The risk of predation has a pervasive influence the lives of prey animals, potentially leading to long-term changes in neurophysiology, morphology, and behaviour [1,2]
Exposure to predation risk can induce specific behavioural traits, such as hypervigilance, chronic immobility, and neophobia, which appear long-lasting when acquired at young ages, including during embryonic development (e.g., [8])
We found that short term exposure to risk during the embryonic period had a marked influence on tadpole survival

Summary

Introduction

The risk of predation has a pervasive influence the lives of prey animals, potentially leading to long-term changes in neurophysiology, morphology, and behaviour [1,2]. No significant changes in tadpole morphology were detected, suggesting that increased survival was facilitated by behavioural changes Nymphs stalk their prey, clinging to habitat structure while using a sit-and-wait foraging strategy [17]. Acilius sp.), whereas survivorship decreased in the presence of non-native crayfish (Orconectes virilis) and trout (Oncorhynchus mykiss) Both beetle larvae employed a sit-and-wait foraging strategy, whereas the crayfish and trout were species that actively pursue prey [21,22,23,24]. Taken together with Benard and Fordyce’s [16] study, these findings suggested that a high-risk environment prepares tadpoles for facing the sit-and-wait foraging tactics of many of their native predators. We predicted that embryonic background risk would promote increased survival for tadpoles facing both predators

Ethics statement

Background risk

Results

Discussion