The First Workers of the Ant Camponotus obscuripes Are a Different Allometric Morph with Relatively Long Antennae to Communicate with Other Larger Colony Members

Saori Watanabe,Eisuke Hasegawa,Ryota Kawauchiya,Mamoru Terayama,Yusuke Fujita,Syunta Mikami,Natsuki Ogusu,Yuuka Murakami

doi:10.1155/2017/4520109

Abstract

The first workers produced by an ant queen with a claustral founding mode are much smaller than the workers after the second generation and are thus called “nanitics.” These nanitics shoulder the initial fate of the colony and thus may be different morphometric morph from the other workers in mature colony to optimize the survival of their own colony. We report here that, in the ant Camponotus obscuripes Mayr, the allometric rules of the nanitics are different from those of other workers in mature colonies, suggesting that the nanitics constitute an independent caste as with soldiers or queens in other species. In addition, the antennae of the nanitics show the minimum absolute length-difference with the mother queen compared to the other traits measured. This result suggests that this small size difference enables C. obscuripes nanitics to communicate with the other members of the colony. Our results indicate that polymorphic societies affect the growth rules of workers.

Highlights

Many ant species show the claustral nest-founding mode, in which a dealated queen produces a few 1st workers using only the reserved nutrition in her body [1,2,3]
There is no significant correlation between the sizes of the same trait of the queens and her nanitics for all the measured traits (Pearson’s correlation coefficient; for all the traits, p > 0.05), meaning that we can treat each nanitic’s data as an independent data point because these results showed that there is no phenotypic correlation between the mother queen and her nanitics
The expected genetic correlation has been covered by differences in nutritional condition among queens because sizes of nanitics have shown to be affected by the initial amount of resources stored in their queen [5]

Summary

Introduction

Many ant species show the claustral nest-founding mode, in which a dealated queen produces a few 1st workers using only the reserved nutrition in her body [1,2,3]. The nanitics are assumed to be under strict constraints in terms of their development to maintain the optimal relationship between size and number This suggests that the nanitics may have different growth rules relating morphological traits to body size compared with other workers in mature colonies. A species showing distinctive polymorphisms has more than one worker-morph, each of which has a different allometric rule for some traits, for example, the small normal workers and the soldiers with a huge head in species of the ant genus Pheidole [complete dimorphism [10]]. We generalized two hypotheses to be tested from this consideration; (1) antennae are the smallest divergent trait between small and large individuals in an ant species, and (2) nanitics may have different allometric rules for several traits (especially for antennae) comparing with workers in mature colonies, meaning that nanitics are a distinct morphological caste as with soldiers in the complete dimorphic species. We tested the above hypotheses and will discuss how the social lives of ants affect the morphological growth rules of workers belonging to different generations

Materials and Methods

Results

Discussion

Disclosure