Jacob Johansson

Jacob Johansson
Lund University | LU · Department of Biology

PhD

About

45
Publications
9,644
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907
Citations
Introduction
I am a theoretical ecologist at Lund University and Imperial College London (Silwood park). I am interested in how organisms and ecological communities respond to environmental changes such as global warming, intensified agriculture or contamination. My research focuses on the seasonal timing of biological events (phenology) such as flowering, bird migration or insect pollinator emergence. I am currently the PI for two interlinked projects in which we study how mass-flowering crops and phenological mismatch with seasonal resource peaks influence population dynamics, competition and life-history optimization among pollinators. For more info, please visit my website: http://www.jacobjohansson.weebly.com
Additional affiliations
April 2010 - present
Lund University
Position
  • Researcher

Publications

Publications (45)
Article
Climate warming has caused the seasonal timing of many components of ecological food chains to advance. In the context of trophic interactions, the match–mismatch hypothesis postulates that differential shifts can lead to phenological asynchrony with negative impacts for consumers. However, at present there has been no consistent analysis of the li...
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Temperature sums are widely used to predict the seasonal timing of yearly recurring biological events, such as flowering, budburst, and hatching. We use a classic energy allocation model for annual plants to compare a strategy for reproductive timing that follows a temperature sum rule (TSR) with a strategy that follows an optimal control rule (OCR...
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Long-term phenology monitoring has documented numerous examples of changing flowering dates during the last century. A pivotal question is whether these phenological responses are adaptive or not under directionally changing climatic conditions. We use a classic dynamic growth model for annual plants, based on optimal control theory, to find the fi...
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The role and importance of ecological interactions for evolutionary responses to environmental changes is to large extent unknown. Here it is shown that interspecific competition may slow down rates of adaptation substantially and fundamentally change patterns of adaptation to long-term environmental changes. In the model investigated here, species...
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Phenology is an important part of life history that is gaining increased attention because of recent climate change. We use game theory to model phenological adaptation in migratory birds that compete for territories at their breeding grounds. We investigate how the evolutionarily stable strategy (ESS) for the timing of arrival is affected by chang...
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It is generally expected that, in environments with pronounced seasonal resource peaks, birds’ reproductive success will be maximised when nestlings’ peak food demand coincides with the timing of high food availability. However in certain birds that stay resident over winter, earlier breeding leads juveniles to join the winter flock earlier, which...
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Local adaptation to rare habitats is difficult due to gene flow, but can occur if the habitat has higher productivity. Differences in offspring phenotypes have attracted little attention in this context. We model a scenario where the rarer habitat improves offspring's later competitive ability – a carryover effect that operates on top of local adap...
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An organism's life history is closely interlinked with its allocation of energy between growth and reproduction at different life stages. Theoretical models have established that diminishing returns from reproductive investment promote strategies with simultaneous investment into growth and reproduction (indeterminate growth) over strategies with d...
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Background: A key innovation may allow one group of species to radiate and replace another, but the role of competition and background extinctions for the replacement process is vigorously debated and unclear. Questions: Is a minimum competitive advantage necessary to initiate replacement? Are background extinctions of the incumbent species necessa...
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This paper should be read as addendum to Dieckmann et al. (J Theor Biol 241:370-389, 2006) and Parvinen et al. (J Math Biol 67: 509-533, 2013). Our goal is, using little more than high-school calculus, to (1) exhibit the form of the canonical equation of adaptive dynamics for classical life history problems, where the examples in Dieckmann et al. (...
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Social information is used widely in breeding habitat se- lection and provides an efficient means for individuals to select hab- itat, but the population-level consequences of this process are not well explored. At low population densities, efficiencies may be reduced be- cause there are insufficient information providers to cue high-quality habita...
Article
Phenological changes among plants due to climate change are well documented, but often hard to interpret. In order to assess the adaptive value of observed changes, we study how annual plants with and without growth constraints should optimize their flowering time when productivity and season length changes. We consider growth constraints that depe...
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The signal crayfish (Pacifastacus leniusculus) was introduced to Sweden in 1960, and it has a high commercial and recreational value, but it may also have negative effects on native ecosystems. To better predict how climate warming will affect population dynamics of this cool-water crayfish, we explored the role of temperature and density dependenc...
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Changes in the seasonal timing of life history events are documented effects of climate change. We used a general model to study how dispersal and competitive interactions affect eco-evolutionary responses to changes in the temporal distribution of resources over the season. Specifically, we modeled adaptation of the timing of reproduction and popu...
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In migratory birds, arrival date and hatching date are two key phenological markers that have responded to global warming. A body of knowledge exists relating these traits to evolutionary pressures. In this study, we formalize this knowledge into general mathematical assumptions, and use them in an ecoevolutionary model. In contrast to previous mod...
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Climate-induced phenological shifts may have serious consequences for organisms and populations, but it is challenging to link such shifts to demographic change. Here, we present an overview of current methodological approaches for studying the demographic consequences of phenological shifts, based on a literature survey of 62 studies on diverse ta...
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The timing of biological events (phenology) is an important aspect of both a species’ life cycle and how it interacts with other species and its environment. Patterns of phenological change have been given much scientific attention, particularly recently in relation to climate change. For pairs of interacting species, if their rates of phenological...
Article
Phenology – the seasonal timing of life history events – is of fundamental importance for many ecological interactions. Direct interactions between organisms such as pollination, competitive contests and predation require overlap in time between interacting life stages. By controlling when dur-ing the year individuals are active and available for o...
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In recent years, climate impact assessments of relevance to the agricultural and forestry sectors have received considerable attention. Current ecosystem models commonly capture the effect of a warmer climate on biomass production, but they rarely sufficiently capture potential losses caused by pests, pathogens and extreme weather events. In additi...
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The role of temporal changes and spatial variability in predation risk and prey's means of mitigating such risks is poorly understood in the context of potential threats of global climate change for migratory birds. Yet nest predation, for example, represents a primary source of reproductive mortality in birds. To assess risk birds must spend time...
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Abstract Many species exhibit two discrete male morphs: fighters and sneakers. Fighters are large and possess weapons but may mature slowly. Sneakers are small and have no weapons but can sneak matings and may mature quickly to start mating earlier in life than fighters. However, how differences in competitive ability and life history interact to d...
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Phenological shifts belong to the most commonly observed biological responses to recent climate change. It is, however, often unclear how these shifts are linked to demography and competitive interactions. We develop an eco-evolutionary model to study adaptation of timing of reproduction in organisms with social dominance hierarchies. We focus on r...
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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...
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Many migratory birds have changed their timing of arrival at breeding grounds in response to recent climate change. Understanding the adaptive value and the demographic consequences of these shifts are key challenges. To address these questions we extend previous models of phenological adaptation to climate change under territory competition to inc...
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Phenological changes are well documented biological effects of current climate change but their adaptive value and demographic consequences are poorly known. Game theoretical models have shown that deviating from the fitness-maximising phenology can be evolutionary stable under frequency-dependent selection. We study eco-evolutionary responses to c...
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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 o...
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Background: The complexity and dynamical nature of community interactions make modelling a useful tool for understanding how communities develop over time and how they respond to external perturbations. Large community-evolution models (LCEMs) are particularly promising, since they can address both ecological and evolutionary questions, and can giv...
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Evolutionary branching has been suggested as a mechanism to explain ecological speciation processes. Recent studies indicate however that demographic stochasticity and environmental fluctuations may prevent branching through stochastic competitive exclusion. Here we extend previous theory in several ways; we use a more mechanistic ecological model,...
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Question: What are the evolutionary consequences of extinctions in ecological communities? Can evolution restore pre-extinction communities by replacing lost ecological strategies with similar ones, or will communities change in fundamental ways and never be the same again? Mathematical approach: We develop and explore a new framework based on evol...
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Sympatric speciation requires coexistence of the newly formed species. If divergence proceeds by small mutational steps, the new species utilize almost the same resources initially, and full speciation may be impeded by competitive exclusion in stochastic environments. We investigate this primarily ecological problem of sympatric speciation by stud...

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Projects (3)
Project
The goal of this project is to study the eco-evolutionary consequences of climate-driven phenological shifts using game theory and population dynamic models. The theories are applied to a range of systems, e.g. timing of flowering in annual plants, migration phenology in birds, prospecting time for nest predation risk and phenological responses in food chains. Another goal is to uphold and further develop the scientific legacy of our friend and colleague Prof. Niclas Jonzén (1973-2015) who initiated this line of research.
Project
The study of information use is critical to understanding individual behavior and how changes in behavior translate into population and community dynamics and evolutionary responses in the Anthropocene. While not the first to recognize this, Holt's (2007) essay on the 'degradation of the subtle information tapestries' that organisms rely on for 'maintaining their Darwinian fitness' is prescient. Environmental changes that affect physical factors (e.g., food, temperature) may be, in many cases, of less or of equal importance than the increasing unfamiliarity and uncertainties associated with environmental change (Kueffer 2015). Accumulating evidence shows many insidious ways that humans impact natural populations through altering the information landscape (Vos et al. 2001, Holt 2007, Barber et al. 2010, Francis et al. 2012) or information timescape (Visser and Lambrechts 1999, Thomas et al. 2001, McNamara et al. 2011). Insidious or subtle, understanding information use in a changing environments and its consequences on behavior, populations, and communities, is a pressing need (Danchin et al. 2004, Dall et al. 2005, Valone 2007, Schmidt et al. 2010). Our work focuses on breeding site selection in birds. Nonetheless, the conclusions generalize across many taxa and contexts. Broadly speaking, all organisms are habitat selectors in ecological and evolutionary time. This include ovipositing in anurans and insects (Refsnider and Janzen 2010), reef fishes seeking refugia from predation (Whiteman and Cote 2004, Huijbers 2012), selection of foraging sites (Clark 2007), or occupying climatic microrefugia (Bennett et al. 2014, Scheffers et al. 2014). If there is spatial heterogeneity in the quality of such sites, individuals will benefit from informed decisions on which to occupy. For taxa in which offspring are restricted in their movements during development, it becomes critical for adults to assess heterogeneity in safety at the scale of breeding territories, ponds, or ovipositing sites over which they can exert adaptive choice in where to nest, den, lay or oviposit. In turn, informed habitat selectors using simple, but definable, rules across one or more spatial scales translate heterogeneity in space into population dynamics (Wiens et al. 1993). Passerines are ideal subjects for a synthesis. Apart from exhibiting a wide range of behavioral strategies for collecting information within and between seasons, individual variation in lifetime reproductive success within passerine species is most strongly correlated with longevity and avoiding nest failure (e.g., McCleery et al 2004, Murphy 2007, Williams 2012). Finding a safe(r) place to breed and holding on to it through time is fundamentally about information.