Peer Review #2 of "The effect of changing topography on the coordinated marching of locust nymphs (v0.2)" [peer_review]

2016 unpublished
Collective motion has traditionally been studied in the lab in homogeneous, obstacle-free environments, with little work having been conducted with changing landscapes or topography. Here, the impact of spatial heterogeneity on the collective motion exhibited by marching desert locust nymphs was studied under controlled lab conditions. Our experimental circular arenas, incorporating a funnel-like narrowing followed by rewidening, did not constitute a major barrier to the locusts; but, rather,
more » ... micked a changing topography in the natural environment. We examined its effects on macroscopic features of the locust collective behavior, as well as the any changes in their marching kinematics. A major finding was that of the limited extent to which the changing topography affected system-level features of the marching locust group, such as the order parameter and the fraction of walking individuals, despite increased crowding at the funnel. Overall, marching kinematics was also very little affected, suggesting that locust marching bands adjust to the environment, with little effect on the overall dynamics of the group. These findings are in contrast to recent theoretical results predicting that environmental heterogeneities qualitatively alter the dynamics of collectively moving particles; and highlight the crucial role of rapid individual plasticity and adaptability in the dynamics of flocks and swarms. Our study has revealed other important features of the marching behavior of the desert locust in addition to its robustness: the locusts demonstrated both, clear thigmotaxis and a tendency to spread-out and fill the available space. PeerJ reviewing PDF | Manuscript to be reviewed 21 Abstract 22 Collective motion has traditionally been studied in the lab in homogeneous, obstacle-free 23 environments, with little work having been conducted with changing landscapes or topography. 24 Here, the impact of spatial heterogeneity on the collective motion exhibited by marching desert 25 locust nymphs was studied under controlled lab conditions. Our experimental circular arenas, 26 incorporating a funnel-like narrowing followed by re-widening, did not constitute a major barrier 27 to the locusts; but, rather, mimicked a changing topography in the natural environment. We 28 examined its effects on macroscopic features of the locust collective behavior, as well as the any 29 changes in their marching kinematics. A major finding was that of the limited extent to which the 30 changing topography affected system-level features of the marching locust group, such as the 31 order parameter and the fraction of walking individuals, despite increased crowding at the 32 funnel. Overall, marching kinematics was also very little affected, suggesting that locust 33 marching bands adjust to the environment, with little effect on the overall dynamics of the group. 34 These findings are in contrast to recent theoretical results predicting that environmental 35 heterogeneities qualitatively alter the dynamics of collectively moving particles; and highlight 36 the crucial role of rapid individual plasticity and adaptability in the dynamics of flocks and 37 swarms. Our study has revealed other important features of the marching behavior of the desert 38 locust in addition to its robustness: the locusts demonstrated both, clear thigmotaxis and a 39 tendency to spread-out and fill the available space. 40 41 Manuscript to be reviewed 63 locust swarm (or by any other animals demonstrating mass terrestrial movement) in natural 64 conditions, which may feature a complex terrain, vegetation etc., obscuring and obstructing the 65 path of the locusts. 66 The effects of an heterogeneous environment on the ability of large systems of moving animals 67 (or particles) to form collective dynamic patterns have been mostly studied in simulations. 68 Theoretical work, using simplified models of collective motion, has predicted that the effect of 69 spatial heterogeneities on the ability of swarms to organize and form synchronized motion is PeerJ reviewing PDF |
doi:10.7287/peerj.2742v0.2/reviews/2 fatcat:zorrbwp3nnbc7psaapul56a7u4