Danny Raj joins IIT Madras as Assitant Professor

Hearty Congratulations to Dr Danny Raj, who has joined the Department of Applied Mechanics and Biomedical Engg as Assistant professor, starting today!

He was a DST-Inspire faculty fellow — which is a prestigious fellowship for bright and young early career scientists between PhD and regular Faculty position — at the Department of Chemcial Engineering at IISc, and he has been a close collaborator of our lab for more than five years.

Our first project together was on understanding the collective motion of fish collectives, where Danny brough his engineering skills to our data-driven modelling approaches. Danny mentored several students from our lab for their thesis project, a couple of which also turned into publications!

We wish all the best to Danny in his new position and we are excited to continue collaborating with him on many problems on collective motion


New paper: Lekking as Collective Behaviour featured on IISc main page!

We recently had a very cool paper accepted in Phil. Transaction of the Royal Society B, titled “Lekking as Collective Behaviour”. This was led by our former PhD student Akanksha Rathore and in collaboration with my colleague Kavita Isvaran.

Akanksha Rathore, Kavita Isvaran and Vishwesha Guttal, 2023, Lekking as collective behaviour, Phil. Trans. R. Soc. B,  378: 20220066, doi: https://doi.org/10.1098/rstb.2022.0066Download PDF ; [Data and Codes]

We are very happy that the work is featured on the IISc main page. I am posting the same content here. The article is written by Akash Kalita.

Mating is generally considered a one-to-one relationship between males and females of a species. However, some wild animals show a rare phenomenon known as lekking. Lekking is a collective behaviour of individuals of a species, in which the males aggregate on traditional breeding grounds. Each male forms his own territory. Females move between these territories to sample males during the mating season. Lekking has been observed in less than 3% of birds and 1% of mammals, and blackbuck are among the only mammals in the Indian subcontinent displaying this behaviour.

A team of researchers at the Centre for Ecological Sciences, IISc, including Akanksha Rathore, Kavita Isvaran and Viswesha Guttal, have been studying lekking in blackbucks in the Velavadar National Park in Gujarat. They argue that the lek can be viewed as collective behaviour, driven by a wide range of social interactions that change over time. 

There are many hypotheses surrounding the formation of a lek. The hotspot hypothesis suggests that a lek overlaps with the home range location of females, whereas the black-hole hypothesis speculates that a lek forms in response to the way females move between male territories before mating. The female-choice hypothesis predicts that females directly influence the formation of leks, as they tend to choose a male who is part of an aggregation rather than a solitary male. 

In the new study, the researchers have used drones for high-resolution video tracking, and have deduced that leks are dynamic. The male-male and male-female interactions within the leks typically change over a breeding season. Apart from moving within their own territories to court females, males also move outside for short spans to try and attract nearby females.

The team also proposes hypotheses for complex interactions between males – for example, two or more neighbouring males may cooperate to chase away an intruder, but also fight against each other when it comes to courting a female. The authors also introduce a computer simulation model to study how males may leave their territories for foraging, which happens independently or in synchrony with neighbouring males leaving for foraging. The researchers suggest that further analysis of leks from the perspective of collective behaviour is needed to fully understand the factors that dictate the formation and maintenance of a lek.


Link to the IISc page: https://iisc.ac.in/unconventional-mating-strategies-in-blackbuck/

Here is a picture of us researchers, taken by the drone!


Best theoretical ecology paper award by ESA

Thrilled to share that a paper led by Nikunj Goel, a former IISc UG student from the first batch of IISc UG program (with physics major) and who worked in our lab for his thesis — has won the “best theoretical ecology paper” award by the Ecological Society of America! 

https://www.journals.uchicago.edu/doi/full/10.1086/708270

Hearty congratulations to Nikunj Goel. This work was done in collaboration with myself, Simon Levin and Carla Staver, when Nikunj was doing his Masters in ecology from Yale, at Carla Staver’s lab.

A little of bit history: Nikunj very cleverly used the reaction diffusion equation ideas and techniques I teach in the spatial ecology course (in Aug 2014) and applied them in a real world context, with excellent match between theory and empirical data. You can look at the figure on top right to see how nicely theory and data match! 

Nikunj is currently a graduate student at the Department of Integrative Biology, University of Texas, Austin, USA.

Dispersal Increases the Resilience of Tropical Savanna and Forest Distributions 

Nikunj Goel, Vishwesha Guttal, Simon A. Levin, and A. Carla Staver. V

Abstract

Global change may induce changes in savanna and forest distributions, but the dynamics of these changes remain unclear. Classical biome theory suggests that climate is predictive of biome distributions, such that shifts will be continuous and reversible. This view, however, cannot explain the overlap in the climatic ranges of tropical biomes, which some argue may result from fire-vegetation feedbacks, maintaining savanna and forest as bistable states. Under this view, biome shifts are argued to be discontinuous and irreversible. Mean-field bistable models, however, are also limited, as they cannot reproduce the spatial aggregation of biomes. Here we suggest that both models ignore spatial processes, such as dispersal, which may be important when savanna and forest abut. We examine the contributions of dispersal to determining biome distributions using a 2D reaction-diffusion model, comparing results qualitatively to empirical savanna and forest distributions in sub-Saharan Africa. We find that the diffusion model resolves both the aforementioned limitations of biome models. First, local dispersive spatial interactions, with an underlying precipitation gradient, can reproduce the spatial aggregation of biomes with a stable savanna-forest boundary. Second, the boundary is determined not only by the amount of precipitation but also by the geometrical shape of the precipitation contours. These geometrical effects arise from continental-scale source-sink dynamics, which reproduce the mismatch between biome and climate. Dynamically, the spatial model predicts that dispersal may increase the resilience of tropical biome in response to global change: the boundary continuously tracks climate, recovering following disturbances, unless the remnant biome patches are too small.


Congratulations to Dr. Akanksha Rathore — who defended her thesis today!

Hearty Congratulations to Dr Akanksha Rathore — who got her supremely well-deserved Dr today! Thanks to two external examiners for their time — Dr Soumey Roy (Bose Institute, Kolkata) and Dr Meg Crofoot (Max Plank Institute, Germany). Dr Soumen Roy from Bose Institute Kolkata was also present at the oral exam today.

Akanksha was a joint PhD student between my lab and that of Kavita Isvaran! It was great fun working in this team, trying to understand collective dynamics of blackbuck herds in the wild. Akanksha’s thesis attempts to solve fundamental and challenging problems in collective behaviour by studying animals in the wild by employing an array of approaches/techniques (see the thesis Synopsis here).

Akanksha’s journey to ecology is fascinating: She came from an engineering background, worked in a software company for a couple of years. She followed her true call — joined Nature Conservation Foundation for an year and worked in NE India in challenging field conditions. She joined our lab at CES in Aug 2015 and she was jointly supervised by my colleague Kavita Isvaran.

Akanksha already has an offer of postdoctoral fellowship: She will be joining Max Planck Institute of Animal Behaviour, Konstanz, Germany in Oct 2021! Konstanz is the leading place for doing research in collective behaviour and I am sure she will continue to do awesome work there.

All the best to Akanksha for her future endeavours!


Welcome to a new UG student, bid adieu to two.

We welcome Prashastha Mishra, a student of biology from IISER Pune, to our lab for her final year research project! She will be working with Krishnapriya Tamma, a postdoc in our lab, to analyse remotely sensed vegetation patterns.

We bid adieu to two UG students: Aakash Sengupta defended his Masters thesis titled “Transitions in Collective Behavioural States in Animal Groups” in Dec 2016. Kushal Appilineni, an IISc UG student from physics department, did his BS project with a bunch of cool analytical calculations of a vegetation pattern formation model. He has moved onto work with Shashi Thutupalli at NCBS for his Masters thesis.


Visit by Sonia Kefi and a workshop near Conoor

Dr Sonia Kefi, a researcher from the CNRS Montpellier and two of her students, Alex Genin and Miguel Berdugo, are visiting our lab for two weeks from 27th Nov to 10th Dec 2015. Our labs are collaborating on developing mathematical models of patterned ecosystems, especially the vegetation of semi-arid ecosystems.

 

The three visitors from France and the three folks from our lab (me, Sumithra and Sabiha) went to a tea estate resort near Conoor in Tamil Nadu, away from the distraction of Bengaluru, to assess the progress we have made so far on our projects.  We also had a guest – Krishnapriya Tamma, a PhD student from NCBS (Dr Uma Ramakrishnan’s student) who gave a fantastic talk on her superb phd thesis. It was a great scientific meeting discussing a number of ideas.

Sonia also gave a departmental seminar at CES on 7th Dec 2015 on ‘Identifying the building blocks of ecological networks

Visit by Sonia and her students is part of travel grant we were awarded early this year by the Indo-French Centre for Applied Mathematics. In the first visit, we visited Montpellier in June this year.

 

 

 


Colloquium at National University of Singapore

I went to Singapore for two days (19th-20th Nov) on an invitation from Ryan Chisholm, a faculty at the Department of Biological Sciences, National University of Singapore. I gave a talk at their weekly colloquium on early warning signals of abrupt ecological transitions, including some of our very recent empirical work on analysis of financial market and savanna ecosystem data.

I also met Ryan’s students and colleagues, and had stimulating discussions on various research topics.


Farewell to a bunch of students

Farewell to several students!  Its one of those bitter-sweet blog posts. Various short-term students who have made substantial contributions to the lab are moving forward. Here is a brief farewell for them! Four undergraduate (UG) students from the first batch of IISc’s four year UG program worked with me for their final year project. Two others who have moved on are Pratik Gupte and Subhankar Chakraborty, both of whom did tremendous work in setting up fish lab for us.

lab_photo_farewellUG_July2015

(from left: Pratik, Nikunj, Vishu, Amitabh, Visweswaran, Athma)

Amitabh Srivastava, a physics major at IISc and an electronic and engineering geek, joined our lab in Oct 2014. He built two drones (a hexacopter and a fixed wing flight) and a very cool elephant height sensor (working with a postdoc, Karpagam Chellaiah, in our lab). He is expected to publish at least one paper describing his novel design of elephant sensor. He is joining a start up in Bangalore that makes cool toys based on cool and simple physics.

Athmanathan (Athma), a math major, first worked with me in his very first year summer for a short project in 2012, and then in the summer of 2013. For his final year project, he jointly worked with me and Srikanth Iyer (mathematics department) on developing a mathematical model for animal grouping with heterogeneous agents. He will be joining a PhD program in Ecology at the University of Tennessee, Knoxville.

Nikunj Goel, a physics major, started working with me almost two years ago in the summer of 2013 building a physical model of critical transitions that won an award! He worked with me and my economics collaborator Srinivas Raghavendra on analysing financial data in the context of critical transitions. For his bachelor’s thesis, he proposed a new early warning signal for abrupt transitions in complex systems and also analyzed a bunch of real data sets. Nikunj will be joining a PhD program in Ecology at Yale University.

Visweswaran was the only bio major of the IISc UG batch to have worked in our lab! He initially tried to work on biofilm experiments and modelling, and finally switched to modelling how scale and strength of ecological interactions affect spatial pattern formation. He is continuing in IISc to get a BS-MS dual degree and will work with my colleague Narendra Dixit of Chemical Engineering department for his masters thesis.

Subhankar Chakraborty, coming from a conservation genetics background, did tremendous work in setting up our experimental lab, navigating through the logistical nightmares of procuring fish, transporting from Kerala and sometimes as far place as West Bengal, working with vendors on setting up aquariums, holding racks, etc. All this required patience that only Subho could have. He is now moving on to more important things in life, and we are waiting to hear about them!

Pratik joined the lab for a short internship from Jan 2015 and worked on experimental set up. He is most famous for his naps in the lab meetings, my classes, and remarkable ways in which he could resolve tricky experimental set up issues. He will be joining a Masters program in Europe (Erasmus Mundus program in Applied Ecology).

The lab will miss all of you, but have a great time ahead. All the best folks.


Student updates: collaborations, conferences and interns

A bunch of student related updates.

Phd Students:  Sumithra Sankaran and Sabiha Sachdeva both visited Montpellier, France to initiate collaboration with Dr Sonia Kefi on an Indo-French grant supported by IFCAM. They spent around a month in Montpellier (I was there for the initial one week) and have started working on an interesting collaborative project on spatial patterns in vegetation and other ecological systems. As of today, they finished attending a three day conference in Paris on Mathematical Models in Ecology and Evolution, 2015 with a distinguished list of speakers from various parts of the world. They too gave talks on their ongoing phd thesis work. They are expected to be back in town by the end of this month.

Jaideep Joshi is having great fun at IIASA, Austria at their annual Young Scientist Summer Program. For three months (June-Aug 2015), he will be working with Ake Bronstrom and Ulf Dieckmann, leading theoretical evolutionary biologists, on a spatial model of public goods dilemma.

Interns: Somewhat surprisingly, I ended up accepting quite a few interns this summer! They have all been fantastic.

The first intern was Arpitha who is doing her MSc in math from Christ University. She did a reading project on the evolution of cooperation in networks and also did various simulations related to that. In the process, I got to learn a few basic terminologies of network theory.

Sampada, a fourth year IISc UG student from math department did a simulational project on merge-split models of swarms.

Gokul Nair, a second year IISc UG student wrote efficient codes on swarming using net-logo which are now being used for the experimental work.

Poornima, a second year student from IISER Pune did a reading project on super organisms.

Hans Kaliaden, a third year IISc UG student majoring in biology read about and wrote a net-logo code on vegetation pattern dynamics that has both individual based and reaction-diffusion based dynamics.

Varsha Shenoy, a second year MSc student from Mysore Univerisity is also working on a short project on vegetation pattern formation!

Science is Fun with so many young students around!


Summer updates by Vishu Guttal: Teaching, travel, and talks

Its time for updates again!  Let me start with myself and will post separately on what students have been upto.

Teaching: In the Jan-April term, I taught the course EC 201, the introductory course on Theoretical and Mathematical Ecology. This was the fourth time that I was teaching this course, but one thing had been bothering me a lot: the course was becoming increasingly inaccessible to biology students (in particular, our own CES phd students). The reason was that once UG students of IISc who had much better math background began to take my course as an elective, the mathematical level of the course became too difficult for CES PhD students many of who come from Masters in Zoology/Botany/Wildlife biology programs where the emphasis on math is minimal to zero. I did not want to miss out either on the UG students so that they are exposed to cool ideas of mathematical ecology or the CES phd students who ought know basics of theoretical ecology. Based on various suggestions, I tried this new solution: which is to let UG students take my course only on alternate years.

So this year, I restricted the class to biology majors who have had little exposure to mathematics. The UG students of IISc were requested not to take the course this year (and they kindly obliged). I thought that this really helped the biology background students to learn at their pace — and they did really well. So I am going to keep this format for the future. Even years: the course is open for all. Odd years, the course is open only for non-math background students.

Travel:  In the second week of June, I went to visit my collaborator Dr Sonia Kefi at Montpellier, France to initiate collaboration on our Indo-French grant from IFCAM. We started off great on a project on spatial pattern formation that will be led by a member of Sonia’s group. Sonia and her team members will visit Bangalore in December and we hope to keep this on for several years!

Popular talk: I gave a couple of popular talks/workshops this summer. One was at Christ University, as a part of the initiative by National Network for Mathematical and Computational Biology (NNMCB) to reach out to local colleges and universities. I spoke about evolution and collective movement in animal groups.

Workshop: I then gave a set of lectures at NCBS at the Monsoon School on the Physics of Life. The audience here were basically a bunch of highly motivated kids from various parts of the country studying physics, math or engineering. The idea was to expose them to biology through the lens of mathematics. I started off showing a graph from Ives et al 2008 paper on how midge populations change over time, and how can we construct a mathematical theory of the same. At the end of four hours, students learnt all the way from building simple model of exponential growth to logistic models to constructing bifurcation diagrams for a consumer-resource model. They were all super delighted when they found that even small changes in external factors can lead to large changes in populations; mathematically, this is captured by saddle node bifurcations.