Slime moulds use heuristics based on within-patch experience to decide when to leave

Abstract

Animals foraging in patchy, non-renewing or slowly renewing environments must make decisions about how long to remain within a patch. Organisms can use heuristics ('rules of thumb') based on available information to decide when to leave the patch. Here, we investigated proximate patch-departure heuristics in two species of giant, brainless amoeba: the slime moulds Didymium bahiense and Physarum polycephalum. We explicitly tested the importance of information obtained through experience by eliminating chemosensory cues of patch quality. In P. polycephalum, patch departure was influenced by the consumption of high, and to a much lesser extent low, quality food items such that engulfing a food item increased patchresidency time. Physarum polycephalum also tended to forage for longer in darkened, 'safe' patches. In D. bahiense, engulfment of any food item increased patch residency irrespective of that food item's quality. Exposure to light had no effect on the patch-residency time of D. bahiense. Given that these organisms lack a brain, our results illustrate how the use of simple heuristics can give the impression that individuals make sophisticated foraging decisions.

Ecological memory and relocation decisions in fungal mycelial networks: responses to quantity and location of new resources

“…From numerous studies on the model species Physarum polycephalum, it is known that myxomycete plasmodia can optimise their network structure to connect separately located multiple resources, avoid unfavorable areas [14,15] and solve mazes [16]. They can remember their past activities to avoid previously explored areas, but can decide to enter unfavorable areas if there is no other choice [17], and the time to leave old food sources is determined heuristically [18]. Therefore, plasmodia of myxomycetes are now considered to have intelligence and cognitive abilities even though they have no brain, central nervous system, nor neural networks [18].…”

The Response of Litter‐Associated Myxomycetes to Long‐Term Nutrient Addition in a Lowland Tropical Forest

“…). Myxomycetes can travel several centimeters per hour in search of optimal conditions or nutrients and in a laboratory setting are able to alter their foraging strategy in response to the quality and locations of available food (Latty and Beekman , ; Yip et al. ).…”

Brainless but Multi-Headed: Decision Making by the Acellular Slime Mould Physarum polycephalum

“…In the absence of complete information, the best an organism can do to decide when to leave a patch is to use heuristics, or 'rules of thumb', based on the limited information it does have available. Physarum polycephalum uses the number of food items it has engulfed as a rule of thumb such that each encounter with a high quality food item (the effect is less strong when food items are of lesser quality) decreases the likelihood the plasmodium leaves the patch [40]. Such incremental departure rules had previously been found in parasitoid wasps [41], bumblebees [42,43] and even humans [44][45][46].…”