Johan Ehrlén

Johan Ehrlén


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Works at Department of Ecology, Environment and Plant Sciences
Telephone 08-16 12 02
Visiting address Svante Arrhenius väg 20 A
Room N442
Postal address Institutionen för ekologi miljö och botanik 106 91 Stockholm



I am co-ordinating the master course "Interactions in ecological communities" ( that is given the second part of the spring semester. 

Master student projects

I am happy supervise master student projects within the fields of plant-animal interactions, plant life histories and plant population dynamics. Check my research projects to perhaps get some ideas.



Research interests

My research focuses on plant-animal interactions and plant population dynamics. An important theme in my research is to link variation in natural selection and population dynamics to environmental variation. One research field concerns how environmental context influences natural selection mediated by pollinators, seed predators and herbivores on plant traits, such as flowering phenology. Another important research objective is to link plant demography and plant population dynamics to explicit environmental and climatic factors and use this information to make more realistic population models for organisms in changing environments.

I am currently the host of one Post-doc, Alicia Valdes, and supervise three Ph.D. students, Tenna Toftegaard, Elsa Fogelström and Beate Proske. 


For a recent list of publications, check:

Research projects

I am currently working with four more specific projects:

(1) Selection on timing of reproduction in plants

The aim of this project is to move beyond the simple recognition that selection is spatially and temporally variable and understand what ultimately drives variation in selection on timing of reproduction in plants. The project focuses on effects of mutualistic and antagonistic interactions with animals and how the outcome of these interactions depends on the environmental context. We also examine how the outcomes of interactions measured in lifetime fitness depend on demographic variation. To study these questions we use long-term data sets to link selection on timing of reproduction and climate and carry out field experiments to identify selective agents and to study quantitative genetic variation in flowering time. 

(2) Host plant utilization in butterflies – effects of climate change on trophic interactions

The overarching aim of this project is to investigate how climate change through differential effects on key life history events in interacting organisms might influence host utilization, selection and population dynamics. We use a model system consisting of the Orange tip butterfly (Anthocharis cardamines) which is strongly associated with the phenology of its crucifer host plants. We use field observations and experimental studies to investigate how host plant and butterfly phenology as well as host utilization vary with climate, and to characterize potential variation in adaptations (of both insects and plants) that influence the interactions. 

(3) Environmental change, genetic variation and viability of plant populations

In this project, we use the perennial herb Primula farinosa as a model system to explore the relationship between genetic variation in adaptive traits and population viability in a changing environment. Combining demographic studies in permanent plots, field experiments, common-garden experiments and stochastic demographic models, we strive to (1) determine how variation in abiotic environmental factors and grazing influence the genetic structure of plant populations, (2) examine how local abiotic factors, climatic variation and grazing influence plant demography, and (3) explore how adaptive genetic variation among and within populations influence population viability and survival in landscapes subject to changes in climate and land use. 

(4) Modelling effects of environmental and climate change on the abundance and distribution of plants

The aim of this project is to develop a modelling framework that links vital rates and population growth rates to key environmental variables and is able to forecast effects of climate change, environmental change and management actions on the abundance and distribution of species. The project deals with both general, theoretical aspects and applications to a number of plant systems in different ecosystems. One key objective is to find accurate and efficient ways to assess relationships between environmental drivers and vital rates. Another important objective is to quantify the effects of intra-specific density. The primary method of investigation is comparative demography, but also field experiments play an important role. 


Last updated: August 22, 2018

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