Imperial College London

Dr Samraat Pawar

Faculty of Natural SciencesDepartment of Life Sciences (Silwood Park)

Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 2213s.pawar CV

 
 
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Location

 

2.4KennedySilwood Park

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Summary

 

Publications

Publication Type
Year
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34 results found

Kontopoulos DG, van Sebille E, Lange M, Yvon-Durocher G, Barraclough T, Pawar Set al., 2018, Phytoplankton thermal responses adapt in the absence of hard thermodynamic constraints

To better predict how populations and communities respond to climatic temperature variation, it is necessary to understand how the shape of the response of fitness-related traits to temperature evolves (the thermal performance curve). Currently, there is disagreement about the extent to which the evolution of thermal performance curves is constrained. One school of thought has argued for the prevalence of thermodynamic constraints through enzyme kinetics, whereas another argues that adaptation can - at least partly - overcome such constraints. To shed further light on this debate, we perform a phylogenetic meta-analysis of the thermal performance curve of growth rate of phytoplankton - a globally important functional group -, controlling for potential environmental effects. We find that thermodynamic constraints have a minor influence on the shape of the curve. In particular, we detect a very weak increase of the maximum curve height with the temperature at which the curve peaks, suggesting a weak "hotter-is-better" constraint. Also, instead of a constant thermal sensitivity of growth across species, as might be expected from strong constraints, we detect phylogenetic signal in this as well as all other curve parameters. Our results suggest that phytoplankton thermal performance curves adapt to thermal environments largely in the absence of hard thermodynamic constraints.

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Kissling WD, Walls R, Bowser A, Jones MO, Kattge J, Agosti D, Amengual J, Basset A, van Bodegom PM, Cornelissen JHC, Denny EG, Deudero S, Egloff W, Elmendorf SC, Alonso Garcia E, Jones KD, Jones OR, Lavorel S, Lear D, Navarro LM, Pawar S, Pirzl R, Rueger N, Sal S, Salguero-Gomez R, Schigel D, Schulz K-S, Skidmore A, Guralnick RPet al., 2018, Towards global data products of Essential Biodiversity Variables on species traits, NATURE ECOLOGY & EVOLUTION, Vol: 2, Pages: 1531-1540, ISSN: 2397-334X

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Garcia-Carreras B, Sal S, Padfield D, Kontopoulos D-G, Bestion E, Schaum C-E, Yvon-Durocher G, Pawar Set al., 2018, Role of carbon allocation efficiency in the temperature dependence of autotroph growth rates, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 115, Pages: E7361-E7368, ISSN: 0027-8424

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Zheng JX-S, Pawar S, Goodman DFM, 2018, Graph Drawing by Stochastic Gradient Descent., IEEE Trans Vis Comput Graph

A popular method of force-directed graph drawing is multidimensional scaling using graph-theoretic distances as input. We present an algorithm to minimize its energy function, known as stress, by using stochastic gradient descent (SGD) to move a single pair of vertices at a time. Our results show that SGD can reach lower stress levels faster and more consistently than majorization, without needing help from a good initialization. We then show how the unique properties of SGD make it easier to produce constrained layouts than previous approaches. We also show how SGD can be directly applied within the sparse stress approximation of Ortmann et al. [1], making the algorithm scalable up to large graphs.

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Bestion E, Garcia-Carreras B, Schaum C-E, Pawar S, Yvon-Durocher Get al., 2018, Metabolic traits predict the effects of warming on phytoplankton competition, ECOLOGY LETTERS, Vol: 21, Pages: 655-664, ISSN: 1461-023X

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Kontopoulos D-G, Garcia-Carreras B, Sal S, Smith TP, Pawar Set al., 2018, Use and misuse of temperature normalisation in meta-analyses of thermal responses of biological traits, PEERJ, Vol: 6, ISSN: 2167-8359

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Rizzuto M, Carbone C, Pawar S, 2018, Foraging constraints reverse the scaling of activity time in carnivores, NATURE ECOLOGY & EVOLUTION, Vol: 2, Pages: 247-+, ISSN: 2397-334X

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Schaum C-E, Barton S, Bestion E, Buckling A, Garcia-Carreras B, Lopez P, Lowe C, Pawar S, Smirnoff N, Trimmer M, Yvon-Durocher Get al., 2017, Adaptation of phytoplankton to a decade of experimental warming linked to increased photosynthesis, NATURE ECOLOGY & EVOLUTION, Vol: 1, ISSN: 2397-334X

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Woodward G, Bonada N, Brown LE, Death RG, Durance I, Gray C, Hladyz S, Ledger ME, Milner AM, Ormerod SJ, Thompson RM, Pawar Set al., 2016, The effects of climatic fluctuations and extreme events on running water ecosystems, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 371, ISSN: 0962-8436

JOURNAL ARTICLE

Pawar S, Dell AI, Savage VM, Knies JLet al., 2016, Real versus Artificial Variation in the Thermal Sensitivity of Biological Traits, AMERICAN NATURALIST, Vol: 187, Pages: E41-E52, ISSN: 0003-0147

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Johnson LR, Ben-Horin T, Lafferty KD, McNally A, Mordecai E, Paaijmans KP, Pawar S, Ryan SJet al., 2015, Understanding uncertainty in temperature effects on vector-borne disease: a Bayesian approach, ECOLOGY, Vol: 96, Pages: 203-213, ISSN: 0012-9658

JOURNAL ARTICLE

Gibert JP, Dell AI, DeLong JP, Pawar Set al., 2015, Scaling-up Trait Variation from Individuals to Ecosystems, ADVANCES IN ECOLOGICAL RESEARCH, VOL 52: TRAIT-BASED ECOLOGY - FROM STRUCTURE TO FUNCTION, Editors: Pawar, Woodward, Dell, Publisher: ELSEVIER ACADEMIC PRESS INC, Pages: 1-17

BOOK CHAPTER

Pawar S, 2015, The Role of Body Size Variation in Community Assembly, ADVANCES IN ECOLOGICAL RESEARCH, VOL 52: TRAIT-BASED ECOLOGY - FROM STRUCTURE TO FUNCTION, Vol: 52, Pages: 201-248, ISSN: 0065-2504

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Pawar S, 2015, The role of body size variation in community assembly, Adv. Ecol. Res., Vol: 52

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Pawar S, Dell AI, Savage VM, 2015, From metabolic constraints on individuals to the eco-evolutionary dynamics of ecosystems, Aquat. Funct. Biodivers. An Eco-Evolutionary Approach, Editors: Belgrano, Woodward, Jacob, Publisher: Elsevier, Pages: In Press-In Press

BOOK CHAPTER

Tang S, Pawar S, Allesina S, 2014, Correlation between interaction strengths drives stability in large ecological networks, ECOLOGY LETTERS, Vol: 17, Pages: 1094-1100, ISSN: 1461-023X

JOURNAL ARTICLE

Pawar S, 2014, Why are plant-pollinator networks nested?, SCIENCE, Vol: 345, Pages: 383-383, ISSN: 0036-8075

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Dell AI, Pawar S, Savage VM, 2014, Temperature dependence of trophic interactions are driven by asymmetry of species responses and foraging strategy, JOURNAL OF ANIMAL ECOLOGY, Vol: 83, Pages: 70-84, ISSN: 0021-8790

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Dell AI, Pawar S, Savage VM, 2013, The thermal dependence of biological traits, Ecology, Vol: 94, Pages: 1205-1206, ISSN: 0012-9658

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Pawar S, Dell AI, Savage VM, 2013, Does consumption rate scale superlinearly? Reply, NATURE, Vol: 493, Pages: E2-E3, ISSN: 0028-0836

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Mordecai EA, Paaijmans KP, Johnson LR, Balzer C, Ben-Horin T, Moor E, McNally A, Pawar S, Ryan SJ, Smith TC, Lafferty KDet al., 2013, Optimal temperature for malaria transmission is dramatically lower than previously predicted, ECOLOGY LETTERS, Vol: 16, Pages: 22-30, ISSN: 1461-023X

JOURNAL ARTICLE

Johnson LR, Lafferty K, McNally A, Mordecai E, Paaijmans K, Pawar S, Ryan SJet al., 2013, Mapping the Distribution of Malaria: current methods and considerations, Infectious Disease Modelling, Hoboken, N.J., Publisher: Wiley-Interscience, Pages: In Press-In Press

BOOK CHAPTER

Pawar S, Dell AI, Savage VM, 2012, Dimensionality of consumer search space drives trophic interaction strengths, NATURE, Vol: 486, Pages: 485-489, ISSN: 0028-0836

JOURNAL ARTICLE

Dell AI, Pawar S, Savage VM, 2011, Systematic variation in the temperature dependence of physiological and ecological traits, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 108, Pages: 10591-10596, ISSN: 0027-8424

JOURNAL ARTICLE

Pawar S, 2009, Community assembly, stability and signatures of dynamical constraints on food web structure, JOURNAL OF THEORETICAL BIOLOGY, Vol: 259, Pages: 601-612, ISSN: 0022-5193

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Pawar S, Koo MS, Kelley C, Ahmed MF, Chaudhuri S, Sarkay Set al., 2007, Conservation assessment and prioritization of areas in Northeast India: Priorities for amphibians and reptiles, BIOLOGICAL CONSERVATION, Vol: 136, Pages: 346-361, ISSN: 0006-3207

JOURNAL ARTICLE

Pawar SS, Birand AC, Ahmed MF, Sengupta S, Raman TRSet al., 2007, Conservation biogeography in North-east India: hierarchical analysis of cross-taxon distributional congruence, DIVERSITY AND DISTRIBUTIONS, Vol: 13, Pages: 53-65, ISSN: 1366-9516

JOURNAL ARTICLE

Biswas S, Pawar SS, 2006, Phylogenetic tests of distribution patterns in South Asia: towards an integrative approach, JOURNAL OF BIOSCIENCES, Vol: 31, Pages: 95-113, ISSN: 0250-5991

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Pawar SS, 2005, Geographical variation in the rate of evolution: Effect of available energy or fluctuating environment?, EVOLUTION, Vol: 59, Pages: 234-237, ISSN: 0014-3820

JOURNAL ARTICLE

Pawar SS, Rawat GS, Choudhury BC, 2004, Recovery of frog and lizard communities following primary habitat alteration in Mizoram, Northeast India., BMC Ecol, Vol: 4

BACKGROUND: Community recovery following primary habitat alteration can provide tests for various hypotheses in ecology and conservation biology. Prominent among these are questions related to the manner and rate of community assembly after habitat perturbation. Here we use space-for-time substitution to analyse frog and lizard community assembly along two gradients of habitat recovery following slash and burn agriculture (jhum) in Mizoram, Northeast India. One recovery gradient undergoes natural succession to mature tropical rainforest, while the other involves plantation of jhum fallows with teak Tectona grandis monoculture. RESULTS: Frog and lizard communities accumulated species steadily during natural succession, attaining characteristics similar to those from mature forest after 30 years of regeneration. Lizards showed higher turnover and lower augmentation of species relative to frogs. Niche based classification identified a number of guilds, some of which contained both frogs and lizards. Successional change in species richness was due to increase in the number of guilds as well as the number of species per guild. Phylogenetic structure increased with succession for some guilds. Communities along the teak plantation gradient on the other hand, did not show any sign of change with chronosere age. Factor analysis revealed sets of habitat variables that independently determined changes in community and guild composition during habitat recovery. CONCLUSIONS: The timescale of frog and lizard community recovery was comparable with that reported by previous studies on different faunal groups in other tropical regions. Both communities converged on primary habitat attributes during natural vegetation succession, the recovery being driven by deterministic, nonlinear changes in habitat characteristics. On the other hand, very little faunal recovery was seen even in relatively old teak plantation. In general, tree monocultures are unlikely to support recovery of natura

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