Water strider females use individual experience to adjust jumping behaviour to their weight within physical constraints of water surface tension

Minjung Baek,Christina J Codden,Sang-Im Lee,Katherine M Lawin,Hangkyo Lim,Piotr G Jablonski,Eunjin Yang,Ho-Young Kim

doi:10.1038/s41598-020-75564-x

Abstract

Different species of water striders match leg speeds to their body sizes to maximize their jump take off velocity without breaking the water surface, which might have aided evolution of leg structures optimized for exploitation of the water surface tension. It is not understood how water striders achieve this match. Can individuals modify their leg movements based on their body mass and locomotor experience? Here we tested if water striders, Gerris latiabdominis, adjust jumping behaviour based on their personal experience and how an experimentally added body weight affects this process. Females, but not males, modified their jumping behaviour in weight-dependent manner, but only when they experienced frequent jumping. They did so within the environmental constraint set by the physics of water surface tension. Females’ ability to adjust jumping may represent their adaptation to frequent increases or decreases of the weight that they support as mating bouts, during which males ride on top of females, start or end, respectively. This suggests that natural selection for optimized biomechanics combined with sexual selection for mating adaptations shapes this ability to optimally exploit water surface tension, which might have aided adaptive radiation of Gerromorpha into a diversity of semiaquatic niches.

Highlights

Different species of water striders match leg speeds to their body sizes to maximize their jump take off velocity without breaking the water surface, which might have aided evolution of leg structures optimized for exploitation of the water surface tension
It is possible that individual water striders adjust their leg speed via personal experience through frequent jumping, which may result in the species-specific angular leg speed that are near the predicted o ptimum[3]
Immediate effect of additional weight on jumping performance—We tested water striders in two conditions of the Additional weight treatment (Fig. 1b; names of explanatory and response variables are in bold italic and their levels/values are in italic): weight-added and weight-not-added

Summary

Introduction

Different species of water striders match leg speeds to their body sizes to maximize their jump take off velocity without breaking the water surface, which might have aided evolution of leg structures optimized for exploitation of the water surface tension. Empirical data confirmed that different species use angular downward speeds of legs that are close to these theoretical optima calculated for each species from the species-specific body mass and leg length[3], which assure that legs interact with un-broken surface of water This ability might have a ided[5] adaptive evolution of leg morphology and micro-structures for optimized exploitation of water surface tension, which is associated with evolutionary colonization of water surface habitats by water striders[4,6]. We conducted experiments (Fig. 1b) to determine whether male and female water striders Gerris latiabdominis use their experience to modify their leg movements during their jumps in the manner that depends on the body weight supported by their legs We predicted that this behavioural change may be more pronounced in females, who naturally experience frequent changes in the weight that is supported by the legs. We predicted that behavioural adjustments of jumping should be performed within the upper limits set by the physical properties of water surface

Methods

Results

Conclusion