Costs of coexistence along a gradient of competitor densities: an experiment with arvicoline rodents
Article first published online: 20 DEC 2006
Journal of Animal Ecology
Volume 76, Issue 1, pages 65–71, January 2007
How to Cite
ECCARD, J. A. and YLÖNEN, H. (2007), Costs of coexistence along a gradient of competitor densities: an experiment with arvicoline rodents. Journal of Animal Ecology, 76: 65–71. doi: 10.1111/j.1365-2656.2006.01175.x
- Issue published online: 20 DEC 2006
- Article first published online: 20 DEC 2006
- Received 30 March 2006; accepted 4 September 2006
- Clethrionomys glareolus;
- density dependence;
- interspecific competition;
- life history;
- Microtus agrestis
- 1Costs of coexistence for species with indirect resource competition usually increase monotonically with competitor numbers. Very little is known though about the shape of the cost function for species with direct interference competition.
- 2Here we report the results of an experiment with two vole species in artificial coexistence in large enclosures, where density of the dominant competitor species (Microtus agrestis) was manipulated. Experimental populations of the subordinate vole species (Clethrionomys glareolus) were composed of same aged individuals to study distribution of costs of coexistence with a dominant species within an age-cohort.
- 3Survival and space use decreased gradually with increasing field vole numbers. Thus, responses to interference competition in our system appeared to be similar as expected from resource competition. The total number of breeders was stable. Reproductive characteristics such as the timing of breeding, and the litter size were not affected. In the single species enclosures a proportion of surviving individuals were not able to establish a breeding territory against stronger conspecifics. Under competition with heterospecifics such nonbreeders suffered high mortality, whereas the breeders survived.
- 4Combined interference of dominant conspecifics and heterospecifics probably increased the frequency of aggressive interactions, social stress and mortality for the weaker individuals within a homogeneous age cohort of the subordinate competitor population.
- 5Our results suggest, that in open systems where bank voles are outcompeted over the breeding season by faster reproducing field voles, animals able to establish a territory may be able to withstand competitor pressure, while nonbreeding bank vole individuals are forced to emigrate to suboptimal forest habitats.