Irregular walks and loops with handedness combines in small-scale movement of
Onychiurus armatus (Collembola)




GÖRAN BENGTSSON*, ELNA NILSSON*, TOBIAS RYDÉN**, MARIA SJÖGREN ÖHRN*,
AND MAGNUS WIKTORSSON**


*Department of Ecology, Lund University, Sölvegatan 37, SE-223 62 Lund, Sweden

**Centre for Mathematical Sciences, Lund University, Box 118, SE-221 00 Lund, Sweden

Abstract

A combination of video recordings, descriptive statistics, and walking
simulations was used to evaluate the small-scale movement pattern of a
soil-dwelling species of Collembola, Onychiurus armatus. Individuals
were found to link periods of irregular walk with those of looping in
a homogeneous environment as well as in one structured to
heterogeneity by physical obstacles. The number of loops varied
between 0 and 44 per hour from one individual to another, and some
individuals made loops by turning right and others by turning left. If
individuals that made at least between 70 and 80% of their loops in
either direction were classified as right- and left-loopers, the
estimated genotype frequencies could not be distinguished from those
expected based on inheritance of the looping direction by the
Hardy-Weinberg model. The distance walked at the edge of an obstacle
increased with its diameter and it is suggested that the curvature of
the obstacle is the cue used to cut-off the turn alternation behaviour
holding the individual at the obstacle. Food deprived O. armatus had a
more winding movement, made more circular loops, and spent more time
at the obstacles than those that were well fed. This behaviour as well
as the looping is interpreted as a more systematic and effective
searching strategy than a random walk.

Key words: spatial heterogeneity, video tracking, migration, dispersal,
soil animal, Hardy-Weinberg, random walk