Jacob Johansson

Dr. Jacob Johansson


Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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23 February 2010 in Personality and Social Psychology Bulletin
Verified
Journal Article
Closed access
VSViren Swami
Viren Swami
DFDavid A. Frederick
David A. Frederick
TAToivo Aavik
Toivo Aavik
LALidia Alcalay
Lidia Alcalay
JAJüri Allik
Jüri Allik
IZIvanka Zivcic-Becirevic
Ivanka Zivcic-Becirevic
This study reports results from the first International Body Project (IBP-I), which surveyed 7,434 individuals in 10 major world regions about body weight ideals and body dissatisfaction. Participants completed the female Contour Drawing Figure Rating Scale (CDFRS) and self-reported their exposure to Western and local media. Results indicated there were significant cross-regional differences in the ideal female figure and body dissatisfaction, but effect sizes were small across high-socioeconomic-status (SES) sites. Within cultures, heavier bodies were preferred in low-SES sites compared to high-SES sites in Malaysia and South Africa (ds = 1.94-2.49) but not in Austria. Participant age, body mass index (BMI), and Western media exposure predicted body weight ideals. BMI and Western media exposure predicted body dissatisfaction among women. Our results show that body dissatisfaction and desire for thinness is commonplace in high-SES settings across world regions, highlighting the need for international attention to this problem.

25 January 2012 in Tree Physiology
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Journal Article
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OFOskar Franklin
Oskar Franklin
JJJacob Johansson
Jacob Johansson
RDRoderick C. Dewar
Roderick C. Dewar
UDUlf Dieckmann
Ulf Dieckmann
RMRoss E. McMurtrie
Ross E. McMurtrie
DEDaniel Epron
Daniel Epron
We review approaches to predicting carbon and nitrogen allocation in forest models in terms of their underlying assumptions and their resulting strengths and limitations. Empirical and allometric methods are easily developed and computationally efficient, but lack the power of evolution-based approaches to explain and predict multifaceted effects of environmental variability and climate change. In evolution-based methods, allocation is usually determined by maximization of a fitness proxy, either in a fixed environment, which we call optimal response (OR) models, or including the feedback of an individual's strategy on its environment (game-theoretical optimization, GTO). Optimal response models can predict allocation in single trees and stands when there is significant competition only for one resource. Game-theoretical optimization can be used to account for additional dimensions of competition, e.g., when strong root competition boosts root allocation at the expense of wood production. However, we demonstrate that an OR model predicts similar allocation to a GTO model under the root-competitive conditions reported in free-air carbon dioxide enrichment (FACE) experiments. The most evolutionarily realistic approach is adaptive dynamics (AD) where the allocation strategy arises from eco-evolutionary dynamics of populations instead of a fitness proxy. We also discuss emerging entropy-based approaches that offer an alternative thermodynamic perspective on allocation, in which fitness proxies are replaced by entropy or entropy production. To help develop allocation models further, the value of wide-ranging datasets, such as FLUXNET, could be greatly enhanced by ancillary measurements of driving variables, such as water and soil nitrogen availability.

24 June 2013 in Games
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Journal Article
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Åke BrännströmÅke Brännström
Åke Brännström
JJJacob Johansson
Jacob Johansson
NFNiels Von Festenberg
Niels Von Festenberg
Adaptive dynamics is a mathematical framework for studying evolution. It extends evolutionary game theory to account for more realistic ecological dynamics and it can incorporate both frequency- and density-dependent selection. This is a practical guide to adaptive dynamics that aims to illustrate how the methodology can be applied to the study of specific systems. The theory is presented in detail for a single, monomorphic, asexually reproducing population. We explain the necessary terminology to understand the basic arguments in models based on adaptive dynamics, including invasion fitness, the selection gradient, pairwise invasibility plots (PIP), evolutionarily singular strategies, and the canonical equation. The presentation is supported with a worked-out example of evolution of arrival times in migratory birds. We show how the adaptive dynamics methodology can be extended to study evolution in polymorphic populations using trait evolution plots (TEPs). We give an overview of literature that generalises adaptive dynamics techniques to other scenarios, such as sexual, diploid populations, and spatially-structured populations. We conclude by discussing how adaptive dynamics relates to evolutionary game theory and how adaptive-dynamics techniques can be used in speciation research.


14 December 2020 in Nature Ecology & Evolution
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Journal Article
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JSJelmer M. Samplonius
Jelmer M. Samplonius
AAAngus Atkinson
Angus Atkinson
CHChristopher Hassall
Christopher Hassall
KKKatharine Keogan
Katharine Keogan
STStephen J. Thackeray
Stephen J. Thackeray
APAlbert B. Phillimore
Albert B. Phillimore

24 November 2014 in Oikos
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Journal Article
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JJJacob Johansson
Jacob Johansson
NKNadiah P. Kristensen
Nadiah P. Kristensen
JNJan‐Åke Nilsson
Jan‐Åke Nilsson
NJNiclas Jonzén
Niclas Jonzén