title: Increasing frequency of low summer precipitation synchronizes dynamics and compromises metapopulation stability in the Glanville fritillary butterfly.
abstract: Climate change is known to shift species' geographical ranges, phenologies and abundances, but less is known about other population dynamic consequences. Here, we analyse spatio-temporal dynamics of the Glanville fritillary butterfly (Melitaea cinxia) in a network of 4000 dry meadows during 21 years. The results demonstrate two strong, related patterns: the amplitude of year-to-year fluctuations in the size of the metapopulation as a whole has increased, though there is no long-term trend in average abundance; and there is a highly significant increase in the level of spatial synchrony in population dynamics. The increased synchrony cannot be explained by increasing within-year spatial correlation in precipitation, the key environmental driver of population change, or in per capita growth rate. On the other hand, the frequency of drought during a critical life-history stage (early larval instars) has increased over the years, which is sufficient to explain the increasing amplitude and the expanding spatial synchrony in metapopulation dynamics. Increased spatial synchrony has the general effect of reducing long-term metapopulation viability even if there is no change in average metapopulation size. This study demonstrates how temporal changes in weather conditions can lead to striking changes in spatio-temporal population dynamics.
authors: Metapopulation Research Centre, Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), Helsinki 00014, Finland Department of Ecology, Environment and Plant Sciences, Stockholm University, Lilla Frescati, Stockholm 106 91, Sweden.
authors: Ayco J M
authors: http://orcid.org/0000-0002-3550-1070
authors: AJ
authors: Tack
authors: Metapopulation Research Centre, Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), Helsinki 00014, Finland Department of Neuroscience and Biomedical Engineering, Aalto University, PO Box 12200, Aalto 00076, Finland.
authors: Tommi
authors: T
authors: Mononen
authors: Metapopulation Research Centre, Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), Helsinki 00014, Finland ilkka.hanski@helsinki.fi.
authors: Ilkka
authors: I
authors: Hanski
mesh_terms: D000818:Animals; D002080:Butterflies / Q000254:growth & development / Q000502:physiology*; D057231:Climate Change; D005387:Finland; D007814:Larva / Q000254:growth & development / Q000502:physiology; D011157:Population Dynamics; D011891:Rain; D012621:Seasons
keywords: Glanville fritillary; climate change; climatic extremes; metapopulation; population dynamics; spatial synchrony