The Evolution of Eusociality: Insights from Comparing Two Indian Paper Wasp Species Unnikrishnan Sruthi1,*, Gadagkar Raghavendra2 1National Centre for Biological Sciences, TIFR, GKVK, Bellary Road, Bangalore560065, India 2Centre for Ecological Sciences, Indian Institute of Science, Bangalore560012, India *Email: sruthiuj@gmail.com (corresponding author): ORCID ID 0000-0002-4991-5012
Online Published on 18 October, 2023. Abstract Eusocial species live in colonies with a reproductive division of labour into fertile reproductive castes and sterile non-reproductive castes, an overlap of generations and cooperative brood care. A further distinction can be usefully made between primitively eusocial species which do not have morphological caste differentiation and highly eusocial species which do. Ropalidia marginata is a tropical primitively eusocial wasp that has been extensively studied, especially compared to other tropical social wasps. R. marginata has several distinct traits, such as a docile queen, well-developed age polyethism, and decentralized work regulation, which makes it different from other primitively eusocial wasps and reminiscent of highly eusocial species. Since tropical wasps, especially those belonging to the genus Ropalidia have been poorly studied, we cannot be sure whether R. marginata is unique or its traits are more common among tropical Ropalidia species. To begin to overcome this problem, we have extended our research to the congeneric and sympatric Ropalidia cyathiformis. Here, we compare and contrast what we now know about these two species, especially concerning their reproductive and non-reproductive division of labour. We find that R. cyathiformis, unlike R. marginata, has a behaviourally dominant queen, weak and rigid age polyethism, likely uses behavioural dominance to regulate worker reproduction and individual workers self-regulate their own non-reproductive activities. We, therefore, conclude that R. marginata is indeed unique and argue that R. marginata is intermediate between primitively and highly eusocial wasps. Top Keywords Ropalidia marginata, Ropalidia cyathiformis, Primitively eusocial, Highly eusocial, Dominance behaviour, Social wasps. Top |