Comparison of solitary and collective foraging strategies of Caenorhabditis elegans in patchy food distributions

Abstract

Collective foraging has been shown to benefit organisms in environments where food is patchily distributed, but whether this is true in the case where organisms do not rely on long-range communications to coordinate their collective behaviour has been understudied. To address this question, we use the tractable laboratory model organism Caenorhabditis elegans , where a social strain ( npr-1 mutant) and a solitary strain (N2) are available for direct comparison of foraging strategies. We first developed an on-lattice minimal model for comparing collective and solitary foraging strategies, finding that social agents benefit from feeding faster and more efficiently simply owing to group formation. Our laboratory foraging experiments with npr-1 and N2 worm populations, however, show an advantage for solitary N2 in all food distribution environments that we tested. We incorporated additional strain-specific behavioural parameters of npr-1 and N2 worms into our model and computationally identified N2's higher feeding rate to be the key factor underlying its advantage, without which it is possible to recapitulate the advantage of collective foraging in patchy environments. Our work highlights the theoretical advantage of collective foraging owing to group formation alone without long-range interactions and the valuable role of modelling to guide experiments. This article is part of the theme issue ‘Multi-scale analysis and modelling of collective migration in biological systems'.

Individual exploration and selective social learning: balancing exploration–exploitation trade-offs in collective foraging

“…Prior work on both classes of models has shown that social information is especially valuable when the costs of individually searching in an environment are high [14][15][16], especially when resource distributions are patchy and sparse. Social learning is also beneficial when social cues are more reliable and can help to assess the quality of resources collectively, for example, in clustered or correlated resource environments [17,18]. However, social learning can be disadvantageous when the proportion of social learners is high and when social cues are unreliable, outdated and bear opportunity costs [19].…”

Sex-specific, pdfr-1-dependent modulation of pheromone avoidance by food abundance enables flexibility in C. elegans foraging behavior

“…6,15,16 Further, many natural isolates feed in groups, 13 and collective foraging may be favored in patchy food environments. 25,26 Thus, the role of population density in C. elegans foraging and dispersal may not be fixed. Indeed, in the wild, balancing selection can simultaneously maintain alleles that promote both strategies.…”

Multi-scale analysis and modelling of collective migration in biological systems

“…It is also well-known that collective foraging based on indirect interactions in social or pre-social insects or based on long-range direct interactions in vertebrates improves the detection and exploitation of food sources. In their article, Ding et al [92] investigate the foraging strategies in Caenorhabditis elegans, a 1 mm long nematode which has very limited sensory modalities and very short-range social interactions. By combining a computational model and experiments carried out on two strains of C. elegans, one social and the other solitary, they show that very simple social interactions such as the detection by an individual of a nearby worm allows the social phenotype to detect more efficiently patchy food sources in the environment.…”