At the core of evolutionary analyses and conservation management is the need for understanding population dynamics, especially the rate of and effects of genetic drift. We have a long history of modeling population genetic dynamics, with implications for real world dynamics. Recently we have also extended our tool-set into that of using whole genome sequencing data to reconstruct changes in population size and admixture events over the past million years, in both fish and butterflies.

 

The Lakes Bävervattnen Project

Hotagen Nature Reserve and Natura 2000 area is located in the County of Jämtland, Sweden. Here, brown trout and Arctic char populations of three water systems are monitored genetically over time since the 1970s. These empirical data feed into many of our projects and are, and have been, used for a variety of fundamental issues relating to population dynamics and conservation genetics of both natural and experimentally released populations. Presently, the long term data series generated within this study provides important basis for the following projects of our group: Genetic monitoring and goals for conservation, Effective population size of metapopulations, and Genetic diversity in environmental monitoring.

Principal Investigators: Linda Laikre, Nils Ryman
Contributing Researchers: Anastasia Andersson, Sara Kurland
 

Genetics and life history dynamics of cryptic, sympatric salmonid populations

Genetically distinct, sympatric populations have been reported in several salmonid species and they are typically detected based on morphological or behavioural differences. In a few, rare cases sympatric populations have also been detected without obvious phenotypical differences, based on genetic data alone (i.e., cryptic populations). We work to understand the evolutionary mechanisms behind such sympatric populations including whether life history divergence occurs or whether, in fact, cryptic sympatric populations can exist in the absence of such divergence. We also address statistical power issues related to the detection of sympatric populations.

Principal Investigators: Linda Laikre, Nils Ryman
Contributing Researchers: Anastasia Andersson
Collaborators: Per Erik Jorde

 

Genetic monitoring and goals for conservation

We study microevolutionary processes relating to conservation issues using empirical genetic data from a wide range of species. We describe patterns of genetic biodiversity over space and time, work to understand the processes that shape these patterns, and recommend how the information can be used for sustainable management and conservation genetic guidelines.  

Principal Investigators: Linda Laikre, Nils Ryman
Contributing Researchers: Anastasia Andersson, Sara Kurland, Maria Celorio, Lovisa Wennerström, Mari Edman

 

Effective population size of metapopulations

The genetically effective population size (Ne) is the most widely used parameter for quantifying and monitoring rates of inbreeding and loss of genetic variation through drift. The concept was developed for single, isolated populations; Ne is defined as the size of an ideal population without the evolutionary forces of mutation, selection or migration that exhibits the same expected rate of genetic drift or inbreeding per generation as the actual, real life population of interest. We develop methods for modelling and understanding the dynamics of Ne in substructured populations (metapopulations), apply these to empirical cases and formulate conservation recommendations. We also address questions associated with estimating Ne from empirical data.  

Principal Investigators: Linda Laikre, Nils Ryman
Contributing Researchers: Sara Kurland
Collaborators: Ola Hössjer

 

Population genomics of butterflies

Understanding the evolutionary history of butterflies, from their origins to how populations have become adapted to their local conditions, is a central goal of our lab. We use a range of genomic based approaches, beginning with assembling high quality genomes. Onto this we then place samples of population variation from regions differening in their environmental conditions, such as from Spain and northern Sweden. Using this data we can then work to reconstruct the demographic history of populations, identify which regions may have undergone strong selective sweeps, as well as investigate specific functional categories of genes to ask if they are showing strong signals of local adaptation compared to the rest of the genome. We also investigate the recombination dynamics within and between species, investigating how this affects the landscape of genetic variation compared to other insects.

Principal Investigators: Christopher WheatKarl Gotthard, Christer Wiklund, Soren Nylin
Contributing Researchers: Christen Bossu, Jason Hill, Lisa Fors, Naomi Pruisscher Keehnen, Peter Pruisscher, Ramprasad Neethiraj

 

Bridging the conservation genetics gap

The goal to protect biodiversity is clearly stipulated in international agreements such as the United Nations Sustainable Development Goals for 2030 (www.un.org/sustainabledevelopment) and the Convention of Biodiversity (www.cbd.int). The ambitions are clearly stated - to maintain biological variation at the levels of genes, species and ecosystems – but implementation is difficult. This is particularly true for the genetic level of biodiversity. Our research, followed by many others, has shown that implementing conservation policy for genetic diversity lags considerably behind work for other biodiversity levels. This is in spite of genetic diversity contributing to the basis of all biodiversity by providing the tools for adaptation to environmental change and, thus, long term survival. Further, decades of conservation genetic research has contributed with a wealth of information of relevance for management, although it has been poorly used. This phenomenon is referred to as the “conservation genetics gap”. We work in multi-disciplinary teams to investigate if and how genetic knowledge is used in management, why the conservation genetic gap exists and what means are effective to bridge it.

Principal Investigators: Linda Laikre
Contributing Researchers: Anastasia Andersson, Lovisa Wennerström, Mari Edman
Collaborators: Annica Sandström, Carina Lundmark, Klas Andersson, Andreas Duit, Sanna Lundquist

 

Genetic diversity in environmental monitoring

Genetic diversity is the basis of all biodiversity and is essential for populations´ and species´ long term survival and adaptation. This is recognized in international conservation policy but poorly implemented in practice. In Swedish environmental monitoring genetic diversity is presently not considered at all. This is a pilot project to suggest how genetic diversity can be included in monitoring programs. Two model species are used representing marine and freshwater habitats – Fucus and brown trout (Salmo trutta) – where our group focuses on the trout whereas the Fucus pilot is run by Professor Kerstin Johannesson at University of Gothenburg.

The brown trout has an ecological key role in many freshwater habitats particularly in mountainous areas where it is often the only or one of only few fish species. These areas are subject to climate changes, and intraspecific diversity of brown trout is also potentially affected by stocking and fishing activities. A unique asset for genetic monitoring is available for brown trout at Stockholm University; a frozen tissue archive covering four decades of sampling; comprising over 40,000 individual tissue samples from more than 200 water sites. This material provides a basis for the pilot study; geographic areas including interlinked water systems reflecting metapopulations of brown trout are selected in collaboration with regional managers and revisited. Potential changes over 30-40 year time spans are investigated using modern genetic techniques and will aid in forming a strategy conservation genetic monitoring.

Principal Investigators: Linda Laikre, Nils Ryman
Contributing Researchers: Anastasia Andersson, Mari Edman, Jerry Andersson
Collaborators: Kerstin Johannesson