It was a really short visit, but we all really enjoyed how they used elegant mathematical and data-driven approaches to understand socio-ecological systems.
Listen to my ‘Thale-Harate’ podcast with Pavan Srinath and Ganesh Chakravarthi in Kananda (ಕನ್ನಡ):
On topics ecology, physics, some of my research work and on doing science in India.
I thoroughly enjoyed the conversation during recording, and I hope you too! Any feedback welcome.
Since its an hour and a half long, here is roughly how the topics of discussions go:
0 – 33 minutes: On ecology, how principles and methods of physics/mathematics can be useful. Includes examples from my own research work on ecosystem collapse and collective animal movement.
33 – 55 minutes: How does research actually happen? Did you have eureka-moments? What is the life of a processor and scientist like at work?
55 mins to 1:25 hrs: On Indian science and global competitiveness.
I am really pleased that a new publication – a first book chapter from lab and first paper of 2019 – is now out! Its led by Jitesh Jhawar, a final year PhD student in our lab and in collaboration with Richard Morris – a former postdoc at NCBS.
Jitesh Jhawar, Richard Morris, and Vishwesha Guttal, 2019, Deriving mesoscopic models of collective behaviour for finite populations, In Handbook of Statistics Vol 40: Integrated Population Biology and Modeling (edited by Arni Srini Rao and C R Rao), Part B, 551-594. DOI: https://doi.org/10.1016/bs.host.2018.10.002; Pre-print from Arxiv; Codes and data on github. Download PDF
Collective behaviours of animal groups are often modelled via agent-based simulations. They are relatively difficult to tract analytically. The main highlight here is that we present two analytical methods that are used in the literature (statistical physics and physical chemistry); we compare which method offers ease of model construction.
A second point worth highlighting is that most analytical methods often assume that group/population sizes are infinitely large. The methods we present accounts for the fact that real animal groups are finite in size and individuals interact with each other in inherently probabilistic ways! The resulting scale of description is also referred to as mesoscopic — a term that appears in the title of the book chapter.
The mesoscopic descriptions yield very counter-intuitive results,; for example, noise can actually facilitate collective order!!! Read the chapter for more details.
The writing style we have adopted is pedagogical so that even undergraduate students from physics and mathematics can understand the methods presented here.
Finally, I also want to highlight that the first author of the paper – Jitesh Jhawar – did his bachelor and masters degrees in Biotechnology – but in this chapter, he uses mathematical techniques like Fokker-Planck equations, Langevin equations, Ito Calculus, etc! So even biology background students can learn hard-core mathematical/theoretical biology if you really love doing theory!
I am super delighted to share this — somewhat belated — news that Sumithra Sankaran has defended her PhD thesis on 7th December 2018. Sumithra’s thesis was on understanding how local interactions, spatial patterns and ecosystem stability are related. Needless to say, Sumithra gave a fabulous presentation and the examiners (including external examiner Prof Partha Sarathi Dutta from IIT Ropar, Department of Mathematics) were super impressed.
It is worth noting – especially for prospective students to our lab – that Sumithra was formally trained in zoology and wildlife biology. Because of her exceptional interest in theory, she did a thesis in theoretical ecology involving fairly involved mathematical calculations, e.g., mean-field models, stochastic differential equations and their analyses via Fokker-Planck equations, cellular automata models. Finally, testing her predictions of theory with empirical data – which required another suite of skills in analysing remotely-sensed data, statistics, and making sense of results in light of theory!
Congratulations to Sumithra – its been so much fun collaboratingworking with you – which I hope we will continue!
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.
I would be writing a series for Resonance on some aspects of theoretical ecology, and from the perspective of a physicist turned ecologist!
The first of the series came out two months ago. I copy paste the abstract here, and here is the link to the pdf if you want to read it in full! Do leave a comment or suggest me how you liked the article and what would you like to cover in the series.
“Common people and even scientists think of ecology as a discipline that exclusively studies wildlife and topics related to environmental pollution. My friends both within and outside the scientific community are often baffled when they hear that I am a physicist doing research in ecology. The aim of this series of articles is to emphasize the less known fact that theory and mathematics have been central to ecology since the inception of this relatively young scientific field. In this first article, I will talk about the following three points. First, I will discuss how the emphasis of the basic science of ecology is much broader than its applied aspects involving the conservation of natural ecosystems. Second, I will discuss a fundamental parallel between statistical physics and ecology that arises because both disciplines emphasize macroscopic systems (e.g., magnetic materials in physics or flocks of birds in ecology) as collectives of interacting units that are more than the sum of their constituents. What makes them fascinating is that interactions at small scales typically give rise to unexpected properties at larger scales. Finally, I will discuss how ecology offers a new and rich set of challenges to mathematically trained scientists because of variations among biological organisms and the role of natural selection in shaping ecological systems, both of which have no parallels in the physical sciences.”
Last Monday, the science correspondent of New Indian Express, Ms. Papiya Bhattacharya, carried out a short article on Mathematical Ecology and the work in our lab.
Here is the screenshot of how it looks in print, and look who is next to our lab!
Priyanka Pulla, an award winning freelance journalist , wrote a blog about our work (with my adviser Prof. Jayaprakash) on early warning signals of ecosystem collapses.
As always, she writes really well (check her blog and her other articles). She also makes some connections to Indian Monsoon and the hypothesis about regime shifts in Monsoon.
Here is a really nice longish article titled Tipping points and Phase transitions on our lab work (most of it from my PhD and postdoc) in a monthly magazine called Fountain Ink – published from Chennai.
To do this story, Mr. Varma (a freelance journalist based in Andhra Pradesh) visited our lab in the month of May for couple of days. We had long interesting conversations on the work. I really enjoyed talking to him, and I hope you will like reading the article.