Population Ecology

Population ecology is the study of how and why the size, density, and structure of populations change. We study several aspects of population ecology.

Spaital population ecology of interacting species: The spatial population dynamics of closely interacting species in a fragmented landscape by examining their life history, behavior and natural history, and using population genetics tools. For instance, we have found that over the long term that (meta)population dynamics of the parasitoids of the butterfly Melitaea cinixa are influenced by host dynamics, dispersal ability, host plant species, hyperparasitism, competition, and temperature mediated phenology. For more details and references scroll down to The green titled section “The effects of species interaction and spatial structure of the landscape on population dynamics and genetic structure.”

Population ecology in the context of biological control of agricultural pests by parasitoids.

Jervis, M.A. Kidd, N.A.C., Mills, N.J., van Nouhuys, S.Singh, A., Yazdani, M. * 2023 Population Dynamics. In: Hardy ICW & Wajnberg E (Eds) Jervis’s Insects as natural enemies: practical perspectives.
Keasar, T., Wajnberg, E. Heimpel, G., Hardy, Ian C.W., Shaltiel, L., Gottlieb, D., van Nouhuys, S. 2023
Dynamic economic thresholds for agricultural pests and the importance of migration between field and off-field locations. Forum article in Economic Entomology. 116(2), 2023, 321–330
Hajek, A. E. and van Nouhuys, S. 2016
Fatal diseases and parasitoids: from competition to facilitation in a shared host
Proceedings of the Royal Society B 283, 10.1098/rspb.2016.0154

Populations dynamics in species invasion

Rao, N. N. and van Nouhuys, S. 2026. More invasive than non-invasive Asteraceae plants can reproduce uniparentally, Biological invasions, in press
van Nouhuys, S., Harris, D. C., Hajek, A. E. 2023
Population level interactions between an invasive woodwasp, an invasive nematode and a community of native parasitoids. Neobiota, 82: 67-88.
van Nouhuys, S., Harris, D. C., Stephen, F. M., Galligan, L. D., Hajek, A. E. 2022
Association of the native parasitic nematode Deladenus proximus with individuals and populations of the native woodwasp Sirex nigricornis. Agricultural and Forest Entomology, 24: 237-246.

Host-ednopsymbiont population dynamics

Duplouy, A., Nair, A.*, Nyman, T., van Nouhuys, S. 2021
Long-term spatiotemporal genetic structure of an accidental parasitoid introduction, and local changes in prevalence of its associated Wolbachia symbiont. Molecular Ecology, 30, 4368-4380
van Nouhuys, S. Kohonen, M*., Duplouy, A. 2016
Wolbachia increases the susceptibility of a parasitoid wasp to hyperparasitism
Journal of Experimental Biology, 219: 2984-2990
Summary feature in Inside JEB
Duplouy, A., Couchoux, C.*, Hanski, I., van Nouhuys, S. 2015
Wolbachia infection in a natural parasitoid wasp population
PLOS One, 10(8): e0134843, doi: 10.1371/journal.pone.013484

The effects of species interaction and spatial structure of the landscape on population dynamics and genetic structure.

The population dynamics of species depend on the distribution and stability of resources and enemies, population size and the extent to which individuals move between resource patches. It isn’t simple to disentangle what biotic and abiotic factors go into explaining the dynamics of species. A recent study showed that increasing synchrony of population dynamics of the butterfly M. cinxia can be explained by weather extremes, and not interaction with natural enemies

Increasing synchrony of butterfly population dynamics are associated with increasing synchrony in weather.

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 landscape

Global Change Biology, 24: 10.1111/gcb.14280

Multilocus genetic clusters for each species mapped onto the map of the Åland islands

We are also using Population genetics tools to exploring the association of population structure with environment (such a habitat connectivity), resource distribution (host population dynamics), life history (i.e. population size and sex ratio), and interactions such as competition (we are using primarily neutral microsatellite markers) of the butterfly M. cinxia and its parasitoids in a landscape.

One clear pattern is that higher trophic level species have lower spatial genetic structure. This is not surprising because as trophic level increases the resource becomes sparse and unpredictable, so individuals must be mobile, leading to population mixing.

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

Duplouy, A., Nair, A., Nyman, T., van Nouhuys, S. 2021

Long-term spatiotemporal genetic structure of an accidental parasitoid introduction, and local changes in prevalence of its associated Wolbachia symbiont. Molecular Ecology, 30, 4368-4380

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

55. Nair, A., Nonaka , E., van Nouhuys, S. 2018 Increased fluctuation in a butterfly metapopulation leads to diploid males and decline of a hyperparasitoid Proceedings of the Royal Society B, 285: 10.1098/rspb.2018.0372

Nair, A., Fountain, T., Ikonen, S., Ojanen, S. P., van Nouhuys, S. 2016. Spatial and temporal genetic structure at the fourth trophic level in a fragmented landscape. Proceedings of the Royal Society B, 283: 10.1098/rspb.2016.0668

Couchoux,, C., Seppä, P., van Nouhuys,, S. 2016. Strong dispersal in a parasitoid wasp overwhelms habitat fragmentation and host population dynamics. Molecular Ecology, doi: 10.1111/mec.13696

van Nouhuys, S. 2016. Diversity, population structure and individual behavior of parasitoids as seen using molecular markersCurrent opinions in Insect Science 14: 94-99.

Couchoux, C., Seppä, P., van Nouhuys, S. 2015. Microsatellites for the parasitoid wasp Hyposoter horticola.Conservation Genetics Resources, 7: 595-597

Nair, A., van Nouhuys, S. 2015. Microsatellite markers for a hyperparasitoid wasp from a fragmented landscape.Conservation Genetics Resources, 7: 565-586

Kankare, M., van Nouhuys, S., Gaggiotti, O., Hanski, I. 2005. Metapopulation genetic structure of two coexisting parasitoids of the Glanville fritillary butterfly. Oecologia, 143: 77-84

(image above) : Multilocus genetic clusters for each species mapped onto the map of the Åland islands