Population and community Ecology

We work mostly on the roles of species interactions among individuals that go on to influence populations and communities. Much of our research has been focused on the effects of the spatial configuration of the environment on these. We test ecological theory using detailed study of the behavior and natural history of species, monitoring of interacting species in the wild, manipulative experiments, and population genetics tools. 

A main long term research system has been the plant-Glanville fritillary butterfly-parasitoid wasp community in the Åland islands, Finland.  Since we moved to the The Centre for Ecological Sciences at the Indian Institute of Science in Bangalore, India in autumn 2021, research based in India is just beginning, which is very exciting. 

Highlights from recent publications

Higher trophic level species, such as parasitoids, only persist in habitat patch networks with a high host occupancy

Wang, S., Brose, U., van Nouhuys, S., Holt, R. D. and Loreau, M. 2021 Metapopulation capacity determines food chain length in fragmented landscapes. Proceedings of the National Academy of Sciences, 118, e2102733118.
_______________________________________________

Long term population genetic structure of interacting species

The genetic signature of introduced parasitoid wasp lineages gives us a window into what has happened in an island archipelago over the 25 years since their accidental introduction, including persistence through population bottlenecks, dispersal and interbreeding, as well as sorting among lineages depending on interaction between a hyperparasitoid and bacterial symbiont. @duplouy_anne @abhevo @Saskyavn @ParasitoidEcol

Press release in English or in Swedish

Article about it in The Guardian

The article:
Duplouy A., Nair A., Nyman T., and van Nouhuys S. (2021). Long-term spatio-temporal genetic structure of an accidental parasitoid introduction, and local changes in prevalence of its associated Wolbachia symbiont. Molecular Ecology. doi: 10.1111/mec.16065

_______________________________________________

Strong direct and indirect interactions between species impact the performance of individuals. However, their impact is mostly swamped out by spatial and temporal variation of host plant quality.

Long term population genetic structure of interact species

We assessed the potential long term and landscape-level effects of plant-pathogen herbivore-parasitoid interactions on their dynamics. We found that while there are strong and weak interactions between species, most are swamped out by spatial and temporal variation of host plant quality.

Opedal, Ø., Ovaskainen, O., Saastamoinen, M., Laine, A-L., van Nouhuys, S. (2020) Host plant availability drives the spatio-temporal dynamics of interacting metapopulations across a fragmented landscape.
Ecology, 101(12):e03186. 10.1002/ecy.3186

_______________________________________________

Causes of spatial synchrony of butterfly population dynamics

During the last 20 years the population dynamics of the Glanville fritillary butterfly has become increasingly spatially synchronized over the Åland islands. We tested several possible mechanisms for this increased spatial synchrony and found that it is closely associated with increased synchrony of some aspects of weather, and is not driven by other aspects of weather, or by natural enemies.

Kahilainen, A., van Nouhuys, S., Schulz, T. & Saastamoinen, M. (2018) Metapopulation dynamics in a changing climate: Increasing spatial synchrony in weather conditions drives metapopulation synchrony of a butterfly inhabiting a fragmented landscapePDF
Global Change Biology, doi:10.1111/gcb.14280

_______________________________________________

Pattern of specificity of a generalist parasitoid wasp

Host species isn’t very important to this generalist parasitoid, but the plant species is, and so is the surrounding environment

The generalist pupal parasitoid Pteromalus apum uses both M. cinxia and M. athalia butterflies as hosts. We found that these two hosts are equivalent with respect to the preference of the mother, development of the offspring and brood sex ratio. However, the host plant species the pupa is on, and where in the environment determined rate of parasitic and sex ratio of the broods.

Reudler J. H., van Nouhuys, S.  (2018) The roles of foraging environment, host species and host diet for a generalist pupal parasitoid. PDF
Entomologia Experimentalis et Applicata, 10.1111/eea.12657