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TORSTEN NYGÅRD KRISTENSEN - Genetic architecture of complex traits

In our group, we work within three main areas; 1) inbreeding and genetic drift in small populations 2) adaptation to variable and stressful environments and 3) genetic architecture of complex traits.


Inbreeding and genetic drift in small populations

In small isolated populations we often see a high rate of inbreeding and genetic drift, which can lead to decreased fitness (inbreeding depression) and loss of genetic variation. We use model organisms such as fruit flies to study how inbreeding and environmental stress interact in their effect on fitness, we use molecular omics technologies to investigate which genes, transcripts, proteins and metabolites are affected by inbreeding and explain variation in inbreeding depression, and we use quantitative genetic tools to e.g. investigate the correlation between the population size and the level of genetic variation. Often we use our model systems to test and challenge theoretical predictions. In more applied projects we use knowledge generated in the lab to guide breeding programs aiming at rescuing threatened wild or domestic populations such as the little owl and cattle and dog breeds.

Adaptation to variable and stressful environments

Natural populations are exposed to large variation in environmental conditions within and between generations. Adaptation to these environments is typically through evolutionary changes or adaptive plastic responses. Climate change and other human influences cause many environments to be unfavorable. We are interested in whether, at what speed, and how, populations can adapt to environments that are changing rapidly. We often use species of fruit flies in these studies, where we exploit the opportunities linked to model species with high fertility, short generation time and sequenced genomes. It enables us to make selection experiments where we, within a short time frame, can select for many generations, and to use omics techniques to examine the genetic basis of adaptation to stress. We are often doing these experiments in the lab, but have in recent years increasingly moved in the direction of conducting field studies and now have a strong focus on the ecological relevance of our work.


Genetic architecture of complex traits

In this part of our work we focus on understanding the genetic architecture of new complex traits. In a recent study we have investigated the genetic basis for how individuals react to environmental variation experienced in their lifetime. It is well known that selection can change the mean of most traits in a population. New results suggest that individual's response to the different environments they experience throughout development and adult life is also under genetic control. This means that natural and artificial selection may favor high plasticity in populations in e.g. variable environments, while individuals in stable environments may be less plastic. In animal and plant breeding this has large implications because it means e.g. that breeding for animals and plants that are robust across environmental gradients is possible. Another project we have recently initiated, focus on using model organisms to investigate the genetic basis of human psychiatric diseases. We expect the results from this project will contribute with knowledge relevant for developing new drugs tailored to individual patients.