Tanmay Dixit

Biography & Research

Tanmay Toucan

I am a PhD student at the University of Cambridge (BA Natural Sciences), studying the evolution and behavioural ecology of brood parasite – host interactions, with fieldwork in Zambia. I graduated from Cambridge in June 2017 and following have studied avian brood parasitism in South Africa and Zambia and interactions between fish species in Trinidadian streams.

Some of my research projects have included studying interactions between pollinators (Heliconius butterflies) and tropical vines (Psiguria), with Prof. Chris Jiggins in Panama, and theoretical work on the interaction between mating systems (specifically self-incompatibility in plants) and genetic barriers with Prof. Nick Barton. I also conducted a meta-analysis on cooperatively breeding vertebrates and maternal effects as one of my Bachelor projects, which has been published in the journal PeerJ.

I am primarily interested in species interactions and behavioural ecology, particularly the consequences of antagonistic arms races on adaptations and animal signals – these interests have been largely inspired by attending seminars and having conversations with members of the Behavioural Ecology Group at Cambridge. Prof. Nick Davies and Prof. Claire Spottiswoode have particularly inspired me and enhanced my interest in both scientific questions and natural history. In particular I have been fascinated by brood parasitism due to the wonderful adaptations, and some seemingly inexplicable maladaptations, that are generated by host-parasite coevolution.

In Zambia I am studying the interactions between cuckoo finches Anomalospiza imberbis and their hosts (family Cisticolidae). I am attempting to understand the mechanisms and adaptive decision-making involved in egg rejection by hosts, as well as why differences exist between some host and parasite eggs. I am collaborating with Prof. L Mahadevan (Harvard) and Dr. Cassie Stoddard (Princeton) to use top-down and bottom-up approaches in studying the evolution of egg signatures and forgeries, and the generation of adaptive repeated randomness. I also aim to understand the effects of coevolutionary arms races, and why outcomes of similar arms races may differ.

Having always been interested in nature, as well as being a keen bird- and wildlife-watcher, I am delighted to be able to pursue these scientific questions in the setting of Zambia’s miombo woodland. A large part of my passion for brood parasitism, ornithology and animal behaviour is inspired by my love of natural history.

Publications

  • Dixit, T., Caves, E.M., Spottiswoode, C.N. & Horrocks, N.P.C. (2021) Why and how to apply Weber’s Law to coevolution and mimicry. Evolution doi:10.1111/evo.14290 Read on journal website [Open Access]
  • Caves, E.M., Dixit, T., Colebrook-Robjent, J.F.R., Hamusikili, L., Stevens, M., Thorogood, R. & Spottiswoode, C.N. (2021) Hosts elevate either within-clutch consistency or between-clutch distinctiveness of egg phenotypes in defence against brood parasites. Proceedings of the Royal Society of London B 288: 20210326. Read on journal website [Open Access]
  • Dixit, T.*, Riederer, J.M.*, Quek, S., Belford, K., Tavares de Wand, T., Sicat, R. & Jiggins, C.D. (2020) Plasticity in flower size as an adaptation to variation in pollinator specificity. Ecological Entomology 45: 1367-1372. Read on journal website [Open Access]
  • Sorensen, M.C., Dixit, T., Newton, J., Kardynal, K., Hobson, K., Bensch, S., Jenni-Eiereman, S. & Spottiswoode, C.N. (2019) Migration distance does not predict blood parasitism in a Palearctic-African migratory bird. Ecology and Evolution 9: 8294-8304. Read on journal website [Open Access]
  • Pickup, M., Brandvain, Y., Fraïsse, C., Yakimowski, S., Barton, N.H., Dixit, T., Lexer, C., Cereghetti, E. & Field, D.L. (2019) Mating system variation in hybrid zones: facilitation, barriers and asymmetries to gene flow. New Phytologist 224: 1035-1047. Read on journal website [Open Access]
  • Dixit, T., English, S. & Lukas, D. (2017), The relationship between egg size and helper number in cooperative breeders: a meta-analysis across species. PeerJ 5:e4028. Read on journal website [Open Access]

News

Dr Gabriel Jamie awarded a Leverhulme Early Career Fellowship

Dr Gabriel Jamie has been awarded a Leverhulme Early Career Fellowship based at University of Cambridge. For the fellowship Gabriel will build on his previous work on brood parasitism and the evolution of polymorphisms to understand the incredible diversity of egg...

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New paper published on Weber’s Law and mimicry

Our paper ‘Why and how to apply Weber’s Law to coevolution and mimicry’ has been published in the journal Evolution. This perspectives paper, written by Tanmay Dixit, Eleanor Caves, Claire Spottiswoode, and Nicholas Horrocks, argues that Weber’s Law of proportional processing can lead to otherwise counterintuitive predictions about the evolutionary trajectories of mimicry systems.  Weber’s Law states that when the magnitude of a stimulus is large, it is more difficult to discriminate a change or difference from that stimulus. In other words, relative differences are more salient than absolute differences. We show that Weber’s Law could have implications for mimicry: when stimulus magnitudes are high, it should be more difficult to discriminate a model from a mimic. This leads to testable predictions about evolutionary trajectories of models and mimics. We also present a framework for testing Weber’s Law and its implications for coevolution. 

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New paper on evolution of egg signatures

Our paper “Hosts elevate either within-clutch consistency or between-clutch distinctiveness of egg phenotypes in defence against brood parasites” has just been published in the journal Proceedings of the Royal Society of London B. In this study, led by Eleanor Caves, we asked how host eggs evolve adaptations that allow them better to discriminate their own eggs from parasitic eggs. Theoretically, hosts can generate their own individually-distinctive egg ‘signatures’ by laying eggs that appear similar to one another (consistency) but look very different from other individuals’ eggs (distinctiveness). In this new study, we show that host species of two African brood parasites deploy either consistency or distinctiveness, but not both, as defences, and achieve distinctiveness by combining egg colours and patterns in unpredictable combinations.

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Mairenn Attwood awarded Cambridge teaching prize

Congratulations to Mairenn Attwood for being awarded the Janet Moore Prize for teaching in the Department of Zoology at the University of Cambridge, for her outstanding tutorial supervision of final-year undergraduate students, who praised her breadth and depth of knowledge, enthusiasm, and friendliness.  Mairenn follows in the footsteps of Tanmay Dixit who was awarded the Janet Moore Prize in 2020. Well done both for inspiring the next generation of behavioural ecologists!

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