Metacommunity structure

A central focus of community ecology is to distinguish between structure due to ecological interactions such as competition, predation and parasitism, and structure due to chance or to extrinsic factors such as habitat fragmentation. In a metacommunity differences among local communities can be used to disentangle these processes, and to assess the role of dispersal among patches in determining community dynamics.

The Glanville fritillary butterfly metapopulation in Åland, Finland is made up of local populations clustered into networks of populations that are dynamic and differ in size, connectivity and age . This is the context experienced by the parasitoids of M. cinxia, and natural variation within this system can be used to test predictions of (meta)community structure.

van Nouhuys, S., Hanski, I. 2005 Metacommunities of butterflies and their parasitoids. In Metacommunities: Spatial Dynamics and Ecological Communities (M. Leibold, R. Holt and M. Holyoak eds.). University of Chicago Press. pp. 99-121 PDF

Tscharntke, T., R. Bommarco, Y. Clough, T. Crist, D. Kleijn, T. Rand, J. Tylianakis, S. van Nouhuys, S.Vidal
2007. Conservation biological control and enemy diversity on a landscape scale.(authors alphabetical after Tscharntke).
Biological Control, 43: 294-309 PDF

Food web around the butterfly Melitaea cinxia in Åland, Finland

Food chain length and contrasting spatial scales of parasitoid populations One important prediction of metacommunity structure is that food chain length decreases with habitat fragmentation. That is, the negative affect of habitat fragmentation increase with trophic level. We approach this idea several ways using the plant-butterfly-parasitoid-hyperparasitoid food chains in Åland. van Nouhuys, S. & Hanski, I. 2002. Multitrophic interactions in space: metacommunity dynamics in fragmented landscapes. In Multitrophic level interactions (T. Tscharntke & B. A. Hawkins eds.) Cambridge University Press. pp. 124-147 PDF

Currently we are planning to take advantage of a large-scale genome scan of all populations of the Glanville fritillary in Åland with many SNPs (Single Nucleotide Polymorphisms) to, among other things, associate the occurrence of each parasitoid with relevant ecological factors including host population size, connectivity and population history.

A second approach is to compare food chain length in Åland with those in other checkerspot communities in less fragmented landscapes (such as in Estonia, Öland), as well as in more complex host butterfly communities (such as Catalonia, Spain).

Kankare, M., Stefanescu, C., van Nouhuys, S., Shaw, M. R. 2005. Host specialization by Cotesia wasps (Hymenoptera: Braconidae) parasitising species-rich Melitaeini (Lepidoptera: Nymphalidae) communities in north-eastern Spain. The Biological Journal of the Linnaean Society, 86: 45-65 PDF

Indirect interactions in the metacommunity
Species interact indirectly through shared enemies (apparent competition), or through intermediate species, such as an herbivore that is experienced by both its food plants and its parasitoids (Multitrophic interactions). These indirect interactions vary spatially, and can influence the large scale population dynamics of species and community structure.

van Nouhuys, S. & I. Hanski 2000. Apparent competition between parasitoids mediated by a shared hyperparasitoid. Ecology Letters, 3: 82-84 PDF

van Nouhuys, S. & I. Hanski 2002. Multitrophic interactions in space: metacommunity dynamics in fragmented landscapes. In Multitrophic level interactions (T. Tscharntke & B. A. Hawkins eds.) Cambridge University Press. pp. 124-147 PDF

The Glanville fritillary butterfly and the closely related Heath fritillary, M. athalia, overlap in distribution in Åland. Preliminary data show that these two butterfly species support the same pupal parasitoid species, but not in the same proportion. We will conduct field experiments are measuring the extent and symmetry of apparent competition between them. Based on the results of the experiment and the overlap in habitat use in Åland we will model this indirect effect of the presence of M. athalia on M. cinxia.

Shaw, M. R, Stefanescu, C., van Nouhuys, S. Parasitoids of European Butterflies in Ecology of Butterflies of Europe (eds. J. Settele, T. G. Shreeve, M. Konvicka & H. Van Dyck) Cambridge University Press, in press.

van Nouhuys, S., Hanski, I. 2004. Natural enemies of checkerspot butterflies. In On the Wings of Checkerspots: A Model System for Population Biology (P. R. Ehrlich & I. Hanski, eds.) Oxford University Press, pp. 161-180 PDF

Kuussaari, M., van Nouhuys, S., Hellmann, J., Singer, M. C. 2004. Checkerspot butterfly larval biology. In On the Wings of Checkerspots: A Model System for Population Biology (P. R. Ehrlich & I. Hanski, eds.) Oxford University Press, pp. 138-160 PDF

Reudler Talsma, J., Torri, K. van Nouhuys, S. 2008 Host plant use by the Heath fritillary butterfly, Melitaea athalia: plant habitat, species and chemistry. Arthropod-Plant Interactions, 2: 63-75 PDF