Raghavendra Gadagkar

Indian Institute of Science | IISC · Centre for Ecological Sciences

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...

Nutrition is an important component of oogenesis and ovarian development in insects. In social insect colonies where a large proportion of females are sterile, suppression of reproduction caused by differential acquisition and retention of nutrition has been hypothesized to cause worker sterility. This study, using the primitively eusocial wasp Rop...

The American myrmecologist, naturalist and writer Edward Osborne Wilson passed away on December 26, 2021. Wilson’s philosophy was “Love the organisms for themselves first, then strain for general explanations, and, with good fortune, discoveries will follow.” Wilson was primarily a social insect specialist who, with characteristic energy, reached o...

Ropalidia marginata is a common primitively eusocial wasp in peninsular India. Their colonies contain a single egg-laying queen and several non-egg-laying workers. Queens and workers are morphologically indistinguishable, and individuals can change from one role to the other. Unlike most primitively eusocial species, queens of R. marginata are doci...

In this new series, I will muse about books I love and reflect on the authors, the content, the style, the context in which the books were written, and what they mean for us today. My goal will be less to convey the book's subject matter and more to inspire my readers to read the book under discussion and books more generally and reflect on the pro...

In this new series, I will muse about books I love and reflect on the authors, the content, the style, the context in which the books were written, and what they mean for us today. My goal will be less to convey the book’s subject matter and more to inspire my readers to read the book under discussion and books more generally and reflect on the pro...

In A Tale of Two Viruses, Neeraja Sankaran traces the parallel histories of two groups of viruses: bacteriophages, which infect bacteria, and sarcoma agents, which cause cancer. Research into these two distinct groups proved to radically reshape what scientists thought they knew, and lay the foundations for our current understanding of viruses.

Reproduction provides direct fitness benefits; therefore, it is important to determine why in some societies certain individuals have disproportionate access to reproductive opportunities. The social interactions that underlie reproductive hierarchies can occur in multiple situations, yet they are rarely studied in unison. The reproductive heir in...

Eusocial insects are characterised by a reproductive caste differentiation such that egg-laying is restricted to a small number of queens. The majority of the colony members function as non-reproducing workers and gain indirect fitness by rearing the offspring of the reproductives. In primitively eusocial species, some workers can also get direct f...

In this book, I introduce readers to the study of animal behaviour by describing simple experiments, both old and new, designed to understand how and why animals behave the way they do. My emphasis is on the design of the experiments and my goal is to motivate readers not only to think about the design but also to come up with alternatives and impr...

Primitively eusocial insects exhibit reproductive division of labour such that one or a small number of individuals monopolize reproduction while the remaining function as non-reproductive workers. They also exhibit non-reproductive division of labour such that some workers primarily perform the extra-nidal tasks of foraging, while others primarily...

I have had multiple aims in writing this series of articles. My primary aim has been to show how simple and innovative experiments can be performed at almost no cost, by nearly anyone, to create significant new knowledge. The history of science shows that this is true in most areas of scientific research, albeit to varying degrees. I have focussed...

Parental Care Since all of us have been children at some time in our lives, and many of us have also been parents at other times, we are well aware of the psychological and physiological importance of parental care, both for the offspring as well as for the parents. But at the same time, we are also painfully aware that there is often some conflict...

That the cuckoo lays its eggs in the nests of other species and does not build its own nest or raise its own offspring, is one of the oldest known facts about Natural History and has been abundantly and eloquently immortalised in myths and stories, art and literature, music and poetry, philosophy and morals. Attempts to understand this curious phe...

There are many examples of perfectly palatable animals resembling related unpalatable species and, thereby, avoiding attack by predators who have learnt or evolved to avoid the unpalatable species. To facilitate recognition by predators, unpalatable species often have warning colourations, which is what is mimicked by the palatable species. This fo...

Charles Darwin proposed a separate theory of sexual selection, as distinct from his theory of natural selection, to account for adaptations that confer success in finding a mate, which may sometimes be quite the opposite of what is best for survival. Darwin’s proposal that females have a sense of beauty and choose mating partners that appear beauti...

An evolutionary biologist recounts his love for the campus of IISc which has also served as a laboratory for his research.

Why should people trust science? Science, we claim, is a work in progress;any fact or theory can be called into question by anybody at any time, as long as they are using the scientific method; science can only falsify hypotheses and not prove any hypothesis correct. Scientists can make mistakes, sometimes inadvertently and sometimes by fraud. Many...

Wonderful as they are, insects do not by any means exhaust the possibilities of suitable organisms to conduct fascinating, cutting-edge, low-cost research, especially in animal behavior. Having seen how insects can be used to this end, in all the previous articles in this series, I will now deliberately choose examples from studies done on vertebra...

Continuing to explore the intriguing world of the Indian paper wasp Ropalidia marginata for one last time, here we will focus on the function of fighting behaviour in two additional contexts (i) the hyper-aggression of the potential queen during queen succession and (ii) during encounters with nonnestmate wasps. We will see again that the function...

Division of labour among workers (non-reproductive division of labour), a characteristic feature of eusocial insects enables the efficient functioning of their colonies. In many advanced insect societies division of labour is based on age (age polyethism). Primitively eusocial insects however are believed to have a weak age polyethism. Here we inve...

Continuing to explore the intriguing world of the Indian paper wasp Ropalidia marginata, here we will focus on their fighting behaviour. When wasps fight, there is, as expected, a winner and a loser. The winner is said to have shown dominance behaviour, and the loser is said to have shown subordinate behaviour. What is the function of such dominanc...

Continuing to explore the fascinating world of the Indian paper wasp Ropalidia marginata, in this article, we will ask how wasps choose their queens in another context. In the previous article in this series, we saw how a simple experiment revealed that wasps fight, i.e., indulge in dominance-subordinate interactions, and the winner becomes the que...

In this, and the next few articles, we will continue to explore the social biology of the primitively eusocial wasp Ropalidia marginata through simple experiments. Since eachwasp colony has a single fertile queen and several sterile workers, and since all or most wasps are capable of taking on both roles, the wasps have to decide who will be the qu...

Non-random space use is common among animals across taxa and habitats. Social insects often use space non-randomly, outside as well as inside their nests. While such non-random space use outside the nest may improve foraging efficiency, inside the nest, it is often associated with the efficient division of labour. Non-random space use by adults on...

In this article, we move from sensory physiology to psychology and consider the proverbially lazy drone. I will describe how some simple experiments permitted us to understand why males in the Indian paper wasp Ropalidia marginata do no work in the colony even during the time they live in it. Taking the behaviour of feeding larvae as an example of...

In this article, I will describe experiments designed to understand how ants estimate the distance they have walked. They rival in their simplicity, the experiments described in my previous article, designed to understand how bees estimate the distance flown. Although ants can also use optic flow to estimate distance, in the absence of optic flow c...

On page 749, Line no. 17 “....total of 6 meters…” to be read as “....total of 12 meters…”

This article describes simple experiments that show that honey bees estimate the distance they have flown, by means of ‘optic flow’, i.e., the extent of image motion experienced by their eyes. The estimated distance is then communicated to the bees at home through the tempo of their dance (number of dance circuits in 15 s) or the duration of the wa...

Cities and Canopies: Trees in Indian Cities by Harini Nagendra and Seema Mundoli of Azim Premji University, is one of the most unusual books I have read in a long time. In this brief essay, I wish to say a few words about the research that has gone into the book, about the book itself and more importantly, about what we can do with their book – we...

Dispersing from the natal nest to found new nests is an avenue for gaining direct fitness for workers in some primitively eusocial insects, especially in species with a perennial nesting cycle where males are present throughout the year. Such nest foundation is difficult to study in nature or in small laboratory cages. Hence, we have investigated t...

In this article, I will describe how a simple, curiosity-based experiment to understand how ants are smart enough to choose the shortest path led the exploration of self-organization and swarm-intelligence and resulted in major applications in computer science and optimization algorithms. The focus will be on curiosity, simplicity, interdisciplinar...

In the second article in the series, I will describe how the young Karl von Frisch, later to become another founding father of ethology and Nobel Laureate, defied established authority to design simple yet logically clever experiments to show that honey bees indeed have colour vision. His experiments forever changed our view of animals and also the...

Page 872: Line 1 For an aspiring ethologist, and one desirous of elevating its prestige, it is inspiring to read Peter and Jeanne Medawar, in a remarkable book entitled A Philosophical Dictionary of Biology [2], describes ethology in the following words... Should be read as: For an aspiring ethologist, and one desirous of elevating its prestige, it...

In this series of articles, I will introduce the reader to the science of ethology, somewhat indirectly by describing simple experiments, both old and new, designed to understand how and why animals behave the way they do. My emphasis will be on the design of the experiments and my goal will be to motivate readers not only to think about the design...

Cooperative breeding decreases the direct reproductive output of subordinate individuals, but cooperation can be evolutionarily favored when there are challenges or constraints to breeding independently. Environmental factors, including temperature, precipitation, latitude, high seasonality and environmental harshness have been hypothesized to corr...

Ropalidia marginata is a social wasp in which colonies consist of a single fertile queen and several sterile workers. If the queen is removed, one of the workers, potential queen (PQ), becomes hyperaggressive and becomes the next queen. The identity of the PQ cannot be predicted in the presence of the queen. The probability of a worker succeeding t...

Social Evolution: Does Collapsing Taxonomic Boundaries Produce a Synthetic Theory? A lead review of Comparative Social Evolution, edited by D. R. Rubenstein and P. Abbot. Cambridge and New York: Cambridge University Press. $115.00 (hardcover); $64.99 (paper). xii + 465 p.; ill.; index. ISBN: 978-1-107-04339-8 (hc); 978-1-107-64792-3 (pb). 2017.

Review of the book 'My Family and Other Animals' by Gerald Malcolm Durrell (1925–1995)

Possessing spatial familiarity with their foraging landscape may enable animals to reduce foraging effort without compromising on foraging benefits. For animals inhabiting feature-rich landscapes, spatial familiarity can increase with increasing age/experience. To check whether this holds for individually foraging tropical social wasp Ropalidia mar...

http://dialogue.ias.ac.in/article/9123/evaluate-the-evaluations

In primitively eusocial insects, many individuals function as workers despite being capable of independent reproduction. Such altruistic behaviour is usually explained by the argument that workers gain indirect fitness by helping close genetic relatives. The focus on indirect fitness has left open the question of whether workers are also capable of...

Insect societies are hallmarks of cooperation because one or a few queens monopolize reproduction and several non-reproductive workers cooperatively raise brood. However, the loss of the queen exposes a colony to potential reproductive conflict, which is resolved only after a new queen takes over. We studied queen succession in natural and experime...

Significance Cooperation and division of labor are two important features of eusocial insects such as ants, bees, wasps, and termites. Using the primitively eusocial wasp Ropalidia marginata , we investigated the minimum requirements for the emergence of cooperation and division of labor, both reproductive and nonreproductive, and their effect on p...