Wednesday, October 11th, 11h00, Room 454 A, Condorcet Building.

Physical constraints on animal performance

David Labonte

EVOLUTIONARY BIOMECHANICS LABORATORY

Senior Lecturer
Faculty of Engineering, Department of Bioengineering
Imperial College London

Abstract: Even the most complex animals are eventually bound by the laws of physics. In this talk, I will discuss two examples to demonstrate how deciphering these physical constraints can improve our understanding of animal performance, behaviour and evolution.

The first example will focus on the biomechanics of plant-feeding in insects, using leaf-cutter ants as model system. Leaf-cutter ants are the world’s first farmers, and the principal insect pest and ecosystem engineers in Latin America. Biomechanical constraints induce a different size-dependence of biting vs leaf-cutting forces, so putting larger workers at a putative advantage. Through a combination of computer vision, photogrammetry and 3D gaming engines, computers can be taught to detect, track, and estimate the size of hundreds of ants at natural foraging sites, so providing the data required to test quantitative hypotheses on optimal size-distributions of ant foraging parties, informed by these mechanical constraints.

In the second example, I will discuss the peculiar allometry of maximum running speed — the fastest animals are neither the smallest nor the largest, but of intermediate size. This unusual allometry can be explained through the comparison of two characteristic energies that limit every musculoskeletal system: the kinetic energy density, which limits performance in small animals, and the work density, which reigns supreme in large animals. The ratio of both energies forms a dimensionless number, Γ. Where problems in hydrodynamics at equal Reynolds number can be considered hydrodynamically similar, muscle contractions with equal Γ may be considered physiologically similar.

Author: David Labonte Imperial College London

Bio: David is a Senior Lecturer in the Department of Bioengineering, Imperial College London. In his research, David combines his two main passions: his love for animals, and his admiration for physics. Together with his group, he investigates the influence of mechanical constraints on the performance, behaviour and evolution of arthropods (and sometimes larger animals or even plants!). Every day, David is deeply grateful that he has a job in which he can follow his interest, and that he gets to work with and learn from the passionate members of his research group

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