DOI: 10.5061/dryad.bzkh18959
title: With a little help from my friends: individual and collaborative performance during trail clearing in leaf-cutting ants

description: Social organisms express collaborative behaviours, allowing them to solve
 problems that exceed their individual capabilities. Group coordination and
 environmental context are some of the factors that may determine the
 performance of individual and collaborative strategies. Using the
 trail-clearing behaviour of leaf-cutting ants, we evaluated experimentally
 for both strategies whether the success probability and clearing time
 depend on problem characteristics and context. We placed obstacles of
 different sizes and shapes (problem characteristics), in trails with
 different foragers’ fluxes and soil roughness (context) in 10 field nests
 of Atta cephalotes, and compared removal success (i.e. if ants could
 remove obstacles) and time of individual and collaborative strategies.
 Very large obstacles could only be removed collaboratively, confirming
 individual limitations for transporting large objects. For all obstacle
 shapes, collaborative removals were more successful but took longer,
 suggesting that coordination among individuals delays these actions.
 Individual strategies were faster, regardless of ant flux. However, as ant
 flux increased, removal success was higher for collaborative than for
 individual removals. Lastly, trail roughness had no effect. This work
 highlights one advantage of sociality, the option of collaboratively
 solving problems that exceed the individual abilities. In addition, it
 reveals the associated costs of joint actions, since they can be
 time-consuming presumably due to coordination problems.Social organisms
 express collaborative behaviours, allowing them to solve problems that
 exceed their individual capabilities. Group coordination and environmental
 context are some of the factors that may determine the performance of
 individual and collaborative strategies. Using the trail-clearing
 behaviour of leaf-cutting ants, we evaluated experimentally for both
 strategies whether the success probability and clearing time depend on
 problem characteristics and context. We placed obstacles of different
 sizes and shapes (problem characteristics), in trails with different
 foragers’ fluxes and soil roughness (context) in 10 field nests of Atta
 cephalotes, and compared removal success (i.e. if ants could remove
 obstacles) and time of individual and collaborative strategies. Very large
 obstacles could only be removed collaboratively, confirming individual
 limitations for transporting large objects. For all obstacle shapes,
 collaborative removals were more successful but took longer, suggesting
 that coordination among individuals delays these actions. Individual
 strategies were faster, regardless of ant flux. However, as ant flux
 increased, removal success was higher for collaborative than for
 individual removals. Lastly, trail roughness had no effect. This work
 highlights one advantage of sociality, the option of collaboratively
 solving problems that exceed the individual abilities. In addition, it
 reveals the associated costs of joint actions, since they can be
 time-consuming presumably due to coordination problems.
description: <b>Sheet ‘Obstacle
 size effect’-</b> Data on the effect of obstacle size on removal
 decision and time for individual and collaborative strategies. We used
 generalized linear mixed models (GLMM) with nest as a random factor. The
 response variables were (1) the proportion of successful removals with
 Binomial distribution (removal decision column), and (2) the removal time
 with Normal distribution (we log-transformed this variable). The
 explanatory variable was the interaction between the removal strategies
 and the obstacle size, and we included the size of clearing ant/s (we used
 a mean size for collaborative removals), and ant flux as
 co-variables. <b>Sheet ‘Obstacle shape
 effect’-</b> Data on the effect of obstacle shape on removal
 decision and time for individual and collaborative strategies. We used
 generalized linear mixed models (GLMM) with nest as a random factor. The
 response variables were (1) the proportion of successful removals with
 Binomial distribution (removal decision column), and (2) the removal time
 with Normal distribution (we log-transformed this variable). The
 explanatory variable was the interaction between the removal strategies
 and the obstacle shape, and we included the size of clearing ant/s (we
 used a mean size for collaborative removals), obstacle mass and ant flux
 as co-variables. <b>Sheet ‘Ant flux
 effect’-</b> Data on the effect of ant flux on removal decision and
 time for individual and collaborative strategies. We used generalized
 linear mixed models (GLMM) with nest as a random factor. The response
 variables were (1) the proportion of successful removals with Binomial
 distribution (removal decision column), and (2) the removal time with
 Normal distribution (we log-transformed this variable). The explanatory
 variable was the interaction between the removal strategies and the ant
 flux, and we included the size of clearing ant/s (we used a mean size for
 collaborative removals), and obstacle mass as co-variables.
 <b>Sheet ‘Trail
 roughness effect’-</b> Data on effect of trail roughness on removal
 decision and time for individual and collaborative strategies. We used
 generalized linear mixed models (GLMM) with nest as a random factor. The
 response variables were (1) the proportion of successful removals with
 Binomial distribution (removal decision column), and (2) the removal time
 with Normal distribution (we log-transformed this variable). The
 explanatory variable was the interaction between the removal strategies
 and the trail roughness, and we included the size of clearing ant/s (we
 used a mean size for collaborative removals), obstacle mass and ant flux
 as co-variables. Statistical analyses were
 performed in the R environment (R Development Core Team, 2013) using the
 package MASS (Venables and Ripley, 2002) and ‘nlme’ (Pinheiro et al.,
 2017).