Adaptive phenotypic variation among clonal ant workers.

Eisuke Hasegawa,Yuuka Murakami,Saori Watanabe,Fuminori Ito

doi:10.1098/rsos.170816

Eisuke Hasegawa, Yuuka Murakami + Show 2 more

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https://doi.org/10.1098/rsos.170816

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Abstract

Phenotypic variations are observed in most organisms, but their significance is not always known. The phenotypic variations observed in social insects are exceptions. Genetically based response threshold variances have been identified among workers and are thought to play several important adaptive roles in social life, e.g. allocating tasks among workers according to demand, promoting the sustainability of the colony and forming the basis of rationality in collective decision-making. Several parthenogenetic ants produce clonal workers and new queens by asexual reproduction. It is not clearly known whether such genetically equivalent workers show phenotypic variations. Here, we demonstrate that clonal workers of the parthenogenetic ant Strumigenys membranifera show large threshold variances among clonal workers. A multi-locus genetic marker confirmed that colony members are genetic clones, but they showed variations in their sucrose response thresholds. We examined the changing pattern of the thresholds over time generating hypotheses regarding the mechanism underlying the observed phenotypic variations. The results support the hypothesis that epigenetic modifications that occur after eclosion into the adult form are the cause of the phenotypic variations in this asexual species.

Highlights

Individual organisms usually show phenotypic variations, socalled ‘individuality’ [1]
The results showed that, at least in these colonies, nest mates of S. membranifera are genetic clones of each other, and there is no evidence that different clones intrude into the colonies like in other parthenogenetic ants [13,15]
At the time of the experiment, there are three daughter queens of the original queen in the colony, but the long rearing periods should replace all the colony members with offspring of the original queen

Summary

Introduction

Individual organisms usually show phenotypic variations, socalled ‘individuality’ [1]. Each individual differs from conspecific individuals in several ways, e.g. shape, behaviour, preferences and so on. These individualities are thought to arise from genetic differences in sexual organisms [2]. In group-living animals, phenotypic variations among members play adaptive roles that.

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