Unpredictability of escape trajectory explains predator evasion ability and microhabitat preference of desert rodents

TY Moore, KL Cooper, AA Biewener, R Vasudevan


Mechanistically linking movement behaviors and ecology is key to understanding the adaptive evolution of locomotion. Predator evasion, a behavior that enhances fitness, may depend upon short bursts or complex patterns of locomotion. However, such movements are poorly characterized by existing biomechanical metrics. We present methods to quantitatively characterize the unpredictability of non-steady-state locomotion.  We then apply the method by examining sympatric rodent species whose escape trajectories differ in dimensionality. Unlike the speed-regulated gait use of cursorial animals to enhance locomotor economy, bipedal jerboa (family Dipodidae) gait transitions likely enhance maneuverability. In field-based observations, jerboa trajectories are significantly less predictable than those of quadrupedal rodents, likely increasing predator evasion ability. Consistent with this hypothesis, jerboas exhibit less anxiety in open fields than quadrupedal rodents, a behavior that varies inversely with predator evasion ability. Our unpredictability metric expands the scope of quantitative biomechanical studies to include non-steady-state locomotion in a variety of evolutionary and ecologically significant contexts.


This study was funded in part by the Chapman Memorial Scholarship to TYM. The authors thank S (Paine) Valdes, YC Yin, JF Chu, and K Jayaram for experimental assistance, and JA Miyamae for digitization, and PA Ramirez for animal care.

author = {Moore, Talia Y. and Cooper, Kimberly L. and Biewener, Andrew A. and Vasudevan, Ramanarayan},

journal = {Nature Communications},

volume = {8},

number = {440},

pages = {1--9},

doi = {doi:10.1038/s41467-017-00373-2},
title = {{Unpredictability of escape trajectory explains predator evasion ability and habitat preference of desert rodents}},