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

About me


My overall interest is in identifying the environmental drivers of variation in natural selection and population dynamics.

A main topic of my current research is how different environmental drivers, such as climatic factors, directly, and indirectly via interactions with insects, influence natural selection on timing of reproduction in plants. Another part of my research regards the role of plastic responses for selection on timing of reproduction.

I am co-leader for RA8 (about Biodiversity and climate) in the Bolin Centre for Climate Research.

I am currently the host of two Post-docs, Alicia Valdes and Elsa Fogelström, and supervise two Ph.D. students, Beate Proske and Torbjörn Lindell.



For a recent list of my publications, see:







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 phenology and plant-insect interactions. Check my research projects to perhaps get some ideas.




I am currently primarily working with four research projects:


(1) Natural selection underlying counter-gradient patterns of environmental and genetic effects of geothermal soil heating on timing of reproduction

In this project, we are examining how small-scale differences in temperature caused by geothermal soil heating influence plastic responses of flowering phenology of perennial plant species, and how this response influences natural selection and genetic responses. We are testing the predictions that: (1) Natural selection is acting to compensate for maladaptive plastic responses, (2) This selection will partly be mediated by interactions with pollinators, insect prey and herbivores, and (3) Higher soil temperatures are associated with small-scale spatial genetic differentiation and local adaptation exhibiting a counter-gradient pattern.

We use four main approaches to test these hypotheses; observational field studies to examine phenotypic trait selection, field experiments to assess the role of pollinators and prey availability as selective agents, climate chamber experiments with offspring from controlled crosses to examine genetically based differences in flowering time, and reciprocal transplantations of offspring from controlled crosses into field sites representing the full gradient of soil heating to assess phenotypic selection, genotypic selection and local adaptation.

This project is funded by the Swedish Research Council, VR.


(2) 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. The project strives to not only explore how abiotic factors and mutualistic and antagonistic interactions influence selection on timing of reproduction in plants, but also to examine how these selective agents are influenced by variation in climatic conditions. Another key objective is to investigate how selection acts on reaction norms of flowering phenology to climatic factors.  To study these questions we use long-term data sets to link selection on timing of reproduction and climate and field experiments to identify selective agents and to study quantitative genetic variation in flowering time.

This project is supported by the Bolin Centre for Climate Research.


(3) 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.

This project is a collaboration with Johan Dahlgren and Owen Jones, University of Southern Denmark and Kristoffer Hylander, Stockholm University, and is funded by the research council FORMAS.


(4) 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.

This project is a collaboration with Jon Ågren, Uppsala University, and is funded by the research council FORMAS.

Last updated: November 25, 2019

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