Resolving spatio-temporal uncertainty in rare resource acquisition: smell the shell
Complex environments present substantial spatio-temporal uncertainty in where and when rare ecological resources become available. How animals navigate this uncertainty to turn the seemingly unpredictable into the predictable is a fundamental question in evolutionary ecology. Here we use subtidal hermit crabs (Pagurus acadianus) as a model system to experimentally test in the field how animals resolve spatio-temporal uncertainty in resource availability. Quadrat sampling within the subtidal zone revealed that hermit crabs face an extreme ecological challenge, based on the rarity of empty shells across space and time. We show how this spatio-temporal uncertainty is ultimately resolved using long-distance chemical cues, which are associated with non-destructive shell predation on living gastropods, the original source of shells. By experimentally releasing cues that simulated the chemical by-products of predation, we reveal that certain flesh cues provide fine-grained information about the precise spatial and temporal window of new shell availability. These cues were most attractive to individuals with the greatest existing resource needs, and in the absence of this information individuals were highly constrained in their ability to discover newly available resources. Broadly, these experiments reveal that exploiting simple cues from heterospecific predators can provide a solution to the general ecological challenge of finding resources that are rare in space and time.
KeywordsCues Information Spatio-temporal uncertainty Resource acquisition Predation
This research was approved by Shoals Marine Laboratory. For valuable field support we thank SML staff, especially Jim Coyer, Mike Rosen, Amber Litterer, Katy Bland, Bonny Clarke, and SML director Jennifer Seavey. We are grateful to all members of the Laidre lab for helpful feedback on the manuscript during a fall 2017 presentation. This research was supported by Dartmouth College startup funds to ML, a UGAR grant to LV and ML, and support from SML. We are especially grateful to Bill Kneisel for his generous gift supporting this line of research. The authors declare no conflicts of interest.
Crab’s eye view of the poor visibility in the subtidal as seaweed washes back and forth in waves, obscuring the view. Footage is of a hermit crab (Pagurus acadianus) in the subtidal of the Isle of Shoals (MOV 22165 kb)
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