Substantial variability in morphological scaling among bumblebee colonies.

C D Perl,C E Restrepo,E Baird,A Miettinen,Z B Johansen,M Guiraud,V W Jie,Z Moradinour

doi:10.1098/rsos.211436

C D Perl, C E Restrepo + Show 6 more

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https://doi.org/10.1098/rsos.211436

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Abstract

Differences in organ scaling among individuals may play an important role in determining behavioural variation. In social insects, there are well-documented intraspecific differences in colony behaviour, but the extent that organ scaling differs within and between colonies remains unclear. Using 12 different colonies of the bumblebee Bombus terrestris, we aim to address this knowledge gap by measuring the scaling relationships between three different organs (compound eyes, wings and antennae) and body size in workers. Though colonies were exposed to different rearing temperatures, this environmental variability did not explain the differences of the scaling relationships. Two colonies had differences in wing versus antenna slopes, three colonies showed differences in wing versus eye slopes and a single colony has differences between eye versus antenna slopes. There are also differences in antennae scaling slopes between three different colonies, and we present evidence for putative trade-offs in morphological investment. We discuss the utility of having variable scaling among colonies and the implication for understanding variability in colony fitness and behaviour.

Highlights

The relative size of an organ with respect to body size impacts on physical and physiological regulation and on how individuals perceive and interact with their world [1,2]
Body size) and the scaling can be positive, in which organs are relatively larger per unit body size, or 2 negative, in which they are relatively smaller per unit body size
Worker mean fresh body mass was higher in colony two than most other colonies ( p < 0.001), but non-significantly different from colony 11

Summary

Introduction

The relative size of an organ with respect to body size impacts on physical and physiological regulation and on how individuals perceive and interact with their world [1,2]. Unlike for most animals, the size of organs relative to body size in the workers of eusocial insects like bumblebees impacts colony, rather than individual, fitness [3]. Workers in a eusocial insect colony are responsible for foraging and brood care, and any failure to perform these behaviours affects the capacity of the colony to produce a new generation of queens and drones. It is worker behaviour, as determined by physiology and morphology, that determines colony fitness

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