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Instytut Biologii Ssaków Polskiej Akademii Nauk, Białowieża

Root vole (Microtus oeconomus) - The effect of physiological traits (body size and metabolic rates) and environmental factors on fitness

Project leader: Karol Zub

Aims of the project:

We are interesting in all physiological traits which could have effect on fitness of animals. We are running several projects concerning influence of metabolic rate and body mass variation on individual fitness (survival rate and reproductive success). Main goal of our investigation is to estimate strength and direction of natural selection on individual body mass, maximum (or peak) metabolic rates (PMR) and basal metabolic rates (BMR) in the population of root vole Microtus oeconomus enclosed by tight fence in their natural habitat. Our study area is located in the Biebrza National Park (about 100 km north-west from Białowieża), near village Gugny.
The basal metabolic rate (BMR) is the minimum energy expenditures which is necessary to keep organism working. In their life cycle individual voles experience strong selection pressure, often characterized by opposite directions. Survival of animals during winter is related to energy expenditures (which are the outcome of metabolic rates and body mass), and in summer is associated with reproductive success, which is positively correlated with body mass. Therefore we expect that small individuals, which better survive winter, will have lower breeding success than larger ones. We are going to test this hypothesis based on survival analyses of individuals of known phenotypic traits and on kinship structure, reconstructed form genetic markers.
Currently, in cooperation with other researches, we investigate relationships between metabolic traits and immune system and food quality. This autumn we begin new project concerning effect of experimentally increased energy expenditures on winter survival of voles.


voles trapping; measurements of basal and maximum metabolic rates (BMR and MaxMR) in lab condition; estimation of field energy expenditures using Doubly Labeled Water method; analyses of silica contents in plants (food avaliability) and animals feces (food quality), analyses of nuclear DNA (changes of genetic structure of investigated population and heritability of body mass, BMR and MaxMR)

Help needed:

We need volunteers for field-work all year round. We are in Biebrza NP every two moths for 2-3 weeks. Field work involves, among others, animals trapping and collecting DNA, and lab work taking care of animals and assistance in metabolic rates measurements. It is possible to participate both in our projects in the Biebrza NP and other projects conducted by Mammal Research Institute staff in Białowieża.

There is a possibility to carry out practice, bachelors or masters projects.

Examples of finished projects (on weasels):

• Habitat selection and home range use by the weasel Mustela nivalis in the Białowieża Primeval Forest, Poland; Leif Sönischen, Institut für Haustierkunde der Christian Albrehts Universität, Kiel, Germany
• Diferences in body size in the least weasel Mustela nivalis in relation to prey avaliability; Willem van de Ven, Van Hall Insitute, the Netherlands
• The influence of testosterone on mean activity time of male weasels; Matthijs Bokje, Van Hall Larenstein, the Netherlands


Szafrańska, P.A., Zub, K. & Konarzewski, M. (2007). Long-term repeatability of body mass and resting metabolic rate in free-living weasels, Mustela nivalis. Funct. Ecol. , 21, 731-737

Zub, K., Sönnichsen, L. & Szafrańska, P. A. (2008). Habitat requirements of weasels Mustela nivalis constrain their impact on prey populations in complex ecosystems of the temperate zone. Oecologia, 157, 571-582

Zub K., Szafrańska P. A., Konarzewski M., Redman P., Speakman J.R. (2009) Tradeoffs between activity and thermoregulation in a small carnivore, the least weasel Mustela nivalis. Proceedings of the Royal Society of London B, 276, 1921–1927



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