Abstract
The fossil record from Seymour Island, Antarctic Peninsula, provides a record of biotic response to the onset of global climatic cooling during the Eocene. Using drilling traces—small, round holes preserved on prey shells—we examined the effect of a cooling pulse 41 Ma on the cannibalistic behaviour of predatory naticid gastropods. We predicted that cannibalistic attacks would decline in response to the cooling climate, reflecting reduced activity levels, energy requirements and constraints on the chemically aided drilling process of the naticids. Surprisingly, however, cannibalism frequencies did not change. This counterintuitive result is best explained by a sharp reduction in durophagous (shell-crushing) predation in shallow-benthic communities in Antarctica that also occurred as the climate cooled. Reduced durophagous predation may have created a less-risky environment for foraging naticids, stimulating cannibalistic behaviour. The change in the top-down control exerted by shell-crushing predators on naticids may have counteracted the direct, negative effects of declining temperatures on the predatory performance of naticids. Our results suggest that the long-term consequences of climate change cannot be predicted solely from its direct effects on predation, because the temperature can have large indirect effects on consumer–resource interactions, especially where risk-effects dominate.
Highlights
Growing evidence suggests that climate change is altering how species interact, especially through the effects of temperature on organismal physiology [1,2,3]
Our results suggest that the long-term consequences of climate change cannot be predicted solely from its direct effects on predation, because the temperature can have large indirect effects on consumer – resource interactions, especially where risk-effects dominate
Despite the potentially limiting effects of low temperatures on the predatory function of Falsilunatia, our results show that cannibalistic drilling frequencies did not decrease with climatic cooling in the La Meseta Formation (LMF)
Summary
Growing evidence suggests that climate change is altering how species interact, especially through the effects of temperature on organismal physiology [1,2,3]. Models of the thermal responses of consumer– resource interactions suggest that if predator and prey possess traits that have asymmetric responses to temperature, such as metabolic rate and body velocity (e.g. how fast a predator moves when foraging for its prey), changes in interaction dynamics are likely to arise [4]. Variation in species’ thermal responses complicates predictions for many interspecific interactions, predicting the responses of intraspecific interactions such as cannibalism may be less problematic, because the consumer and the ‘resource’ possess traits that respond more or less identically to temperature. Because chemical reactions are slower at lower temperatures, it is likely that dissolution is retarded [13], which should increase the time required to complete an attack, reducing opportunities for future cannibalism [14]
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