Prof Guy Theraulaz, a world leader in the field of collective behaviour, visited CES as IISc Infosys Chair Professor from 4th Sept 2019 to 23rd Sept 2019. Prof Theraulaz is currently a senior research fellow at the National Center for Scientific Research CNRS). He is also a leading researcher in the field of swarm intelligence, primarily studying social insects but also distributed algorithms, e.g. for collective robotics, directly inspired by nature.
Contrary to the expected hypothesis that crop-raiding elephants in a human-dominated landscape will exhibit higher stress, the authors found that the stress levels were lower than expected, and it could be due to access to the superior quality of diet (as shown by higher NDVI and faecal Nitrogen content).
Salient findings of the study:
Lower levels of faecal glucocorticoid metabolites (as a proxy of stress) in crop-raiding elephants, than the elephants in protected forests.
This paper deals with how wild Asian elephants react towards the injured, dying and dead conspecifics. The branch of science that deals with understanding the reactions of individuals towards dead or death is termed 'Thanatology'. This is the first documentation on Asian elephants thanatological behaviour.
Link to publication: https://link.springer.com/article/10.1007%2Fs10329-019-00739-8
The evolution of flamboyant traits in animals is typically attributed to the selective force of sexual selection. However, natural selection can constrain the degree of elaboration of such traits. Therefore, animal signals reflect a balance between natural and sexual selection. I examined the role of these forces in the maintenance of a complex visual signal: dynamic colour change. Males of the Indian rock agama (*Psammophilus dorsalis*) exhibit rapid dynamic colour changes on their dorsal and lateral body regions during social interactions. The costs, benefits and adaptive significance of this relatively rare signal type is yet unknown.
Using a combination of visual modelling and field experiments, I first examined the predation risk on social colours and found that the courtship signal of males is costlier than the aggression signal. I then tested whether male colours expressed during aggression convey information about individual physiology and performance measures. Apart from a negative association between testosterone levels and the yellow colour expressed during aggression, body size and bite force were correlated, suggesting that body size could be an honest predictor of fighting ability. In the third chapter, I examined differences in health parameters of males and females that occupy dramatically different habitats as a consequence of urbanization. Our results suggest that lizards in urban areas appear to have shifted their innate physiology in order to cope with urban stressors. Finally, I examined the response of receivers to different components of the male colour signals by assessing attention paid by conspecific receivers to each signal component independently and together. Both males and females responded equally to all male social colours although females showed difference in response to achromatic signals. Overall, we conclude that dynamic colour change may have evolved in this species to actively balance the costs of predation risk with the benefits of social signalling.
Previous studies have argued that movement of organisms typically does not favour animals helping or cooperating each other. Therefore, in species that exhibit collective movement and fission-fusion among groups, cooperation is considered unlikely to occur. In a recent paper published in PLoS Computational Biology, Jaideep Joshi (PhD student), Vishwesha Guttal and collaborators from Germany and USA challenge this common perception.
A new study published in the journal eLife shows that tree crickets manufacture surprisingly accurate optimal aids for sound amplification. This work was led by Natasha Mhatre (a former PhD student of CES), Rittik Deb (a recent PhD student of CES), Rohini Balakrishnan and collaborators from UK (Robert Malkin and Daniel Robert).
Worker castes of fungus-growing termite depositing “agar boluses” on the fungal plug of weedy
Pseudoxylaria (from the October issue of Journal of Chemical Ecology). Photo Credit: Nikhil More
Lakshya Katariya and colleagues (Renee M Borges’ lab) discover that fungus-farming termites
selectively bury the weedy fungi that smell different from crop fungi
Recent research findings by a CES Ph.D. student Sanjeeta Sharma Pokharel, Prof. Polani B Seshagiri (MRDG, IISc) and Prof. Raman Sukumar (CES, IISc) show that the stress levels and body condition of elephants varied between seasons. Wild Asian elephants were showed ‘poor’ body condition and were found to be ‘more’ stressed during resource-deficient periods. This pattern was more conspicuous in female Asian elephants.