The lectotypes of two Malagasy Ropalidia (=Icaria) species, Icaria galimatia de Saussure, 1853, and Icaria ignobilis de Saussure, 1890, are designated. Consequently their synonymy is established. Ropalidia galimatia (de Saussure) is... more
The lectotypes of two Malagasy Ropalidia (=Icaria) species, Icaria galimatia de Saussure, 1853, and Icaria ignobilis de Saussure, 1890, are designated. Consequently their synonymy is established. Ropalidia galimatia (de Saussure) is redescribed and its distribution and the queen/worker size dimorphism are briefly noted.
The holotype of Icaria xanthura de Saussure, 1854, is in the Natural History Museum, London. The species is decidedly a senior synonym of Charterginus aberrans (Gribodo, 1892), a Neotropical polistine species. Development of the... more
The holotype of Icaria xanthura de Saussure, 1854, is in the Natural History Museum, London. The species is decidedly a senior synonym of Charterginus aberrans (Gribodo, 1892), a Neotropical polistine species. Development of the "parategula" in Charterginus is briefly discussed.
The relative abundance of swarm-founding species among social wasps in tropical Africa is assessed, based on field work in the Central African Republic. Two swarm-founding species, belonging to the genus Polybioides, and II... more
The relative abundance of swarm-founding species among social wasps in tropical Africa is assessed, based on field work in the Central African Republic. Two swarm-founding species, belonging to the genus Polybioides, and II independent-founding species, belonging to the genera Polistes, Belonogaster and Ropalidia, were collected. The two swarm-founding species represented less than 3% of nests, and 20% of all foragers. The preponderance of independent-founding species contrasts with relative proportions reported from the Neotropics, tropical Australia, and Southeast Asia.
Varying complexities in two eusocial wasp species R. marginata and R. cyathiformis. c Dominance patterns vary differently across species w.r.t. hierarchical ranks. c A model suggesting a common interaction pattern with simple changes in... more
Varying complexities in two eusocial wasp species R. marginata and R. cyathiformis. c Dominance patterns vary differently across species w.r.t. hierarchical ranks. c A model suggesting a common interaction pattern with simple changes in strategies. c The model could give rise to the observed patterns in both the species. c A possible pathway for the evolution of complex societies from simpler ones.
A major question in current network science is how to understand the relationship between structure and functioning of real networks. Here we present a comparative network analysis of 48 wasp and 36 human social networks. We have compared... more
A major question in current network science is how to understand the relationship between structure and functioning of real networks. Here we present a comparative network analysis of 48 wasp and 36 human social networks. We have compared the centralisation and small world character of these interaction networks and have studied how these properties change over time. We compared the interaction networks of (1) two congeneric wasp species (Ropalidia marginata and Ropalidia cyathiformis), (2) the queen-right (with the queen) and queen-less (without the queen) networks of wasps, (3) the four network types obtained by combining (1) and (2) above, and (4) wasp networks with the social networks of children in 36 classrooms.We have found perfect (100%) centralisation in a queen-less wasp colony and nearly perfect centralisation in several other queen-less wasp colonies. Note that the perfectly centralised interaction network is quite unique in the literature of real-world networks. Differences between the interaction networks of the two wasp species are smaller than differences between the networks describing their different colony conditions. Also, the differences between different colony conditions are larger than the differences between wasp and children networks. For example, the structure of queen-right R. marginata colonies is more similar to children social networks than to that of their queen-less colonies. We conclude that network architecture depends more on the functioning of the particular community than on taxonomic differences (either between two wasp species or between wasps and humans).
I present a hierarchy of models that illustrate, within the framework of inclusive fitness theory, how demographic factors can predispose a species to the evolution of eusociality. Delayed reproductive maturation lowers the inclusive... more
I present a hierarchy of models that illustrate, within the framework of inclusive fitness theory, how demographic factors can predispose a species to the evolution of
eusociality. Delayed reproductive maturation lowers the inclusive fitness of a solitary foundress relative to that of a worker. Variation in age at reproductive maturity makes the worker strategy more profitable to some individuals than to others and thus predicts the coexistence of single-foundress and multiplefoundress nesting associations. Delayed reproductive maturation and variation in age at reproductive maturity also select for mixed reproductive strategies so that some individuals whose
reproductive maturation is expected to be delayed can first act as workers and later switch over to the role of a queen or foundress. Assured fitness returns shows how identical mortality rates can have different consequences for workers and solitary nest foundresses because a solitary foundress will have to necessarily survive for the entire duration of development of her brood, whereas a worker can hope to get proportional
fitness returns for short periods of work. In concert with assured fitness returns, delayed reproductive maturation and variation in age at reproductive maturity become more powerful in selecting for worker behavior, and mixed reproductive strategies become available to a wider range of individuals. These phenomena provide a consistently more powerful selective advantage for the worker strategy than do genetic asymmetries created by haplodiploidy.
Unlike other primitively eusocial wasps, Ropalidia marginata colonies are usually headed by remarkably docile and behaviourally non-dominant queens who are nevertheless completely successful in maintaining reproductive monopoly. As in... more
Unlike other primitively eusocial wasps, Ropalidia marginata colonies are usually headed by remarkably docile and behaviourally non-dominant queens who are nevertheless completely successful in maintaining reproductive monopoly. As in other species, loss of the queen results in one of the workers taking over as the next queen. But unlike in other species, here, the queen's successor cannot be predicted on the basis of dominance rank, other behaviours, age, body size or even ovarian development, in the presence of the former queen. But the swiftness with which one and only one individual becomes evident as the potential queen led us to suspect that there might be a designated successor to the queen known to the wasps, even though we cannot identify her in the queen's presence. Here, we present the results of experiments that support such a ‘cryptic successor’ hypothesis, and thereby lend credence to the idea that queen (and potential queen) pheromones act as honest signals of their fertility, in R. marginata.
