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The Effects of Extreme Weather Events on Ectothermic Species

Paper Reviewed
Malinowska, A.H., van Strien, A.J., Verboom, J., WallisdeVries, M.F. and Opdam, P. 2014. No evidence of the effect of extreme weather events on annual occurrence of four groups of ectothermic species. PLOS ONE 9: e110219.

Noting that regional population dynamics are important for the conservation of species in a time of climate change, especially in temperate Europe where natural habitats are highly fragmented and immersed in an inhospitable landscape matrix, Malinowska et al. (2014) investigated "how weather variability affects the probabilities of occupancy, colonization and persistence of four different groups of organisms -- Odonata (58 dragonfly and damselfly species), Orthoptera (32 grasshopper and cricket species), Lepidoptera (37 butterfly species) and Reptilia (7 reptile species) -- over the entire expanse of the Netherlands on a 1x1-km grid base from 1990 up to the present, while corresponding weather data acquired at De Bilt (which represent the country's general weather pattern) were obtained from the Royal Netherlands Meteorological Institute.

This work revealed, according to the five Dutch scientists, that (1) "all groups, except butterflies, showed more positive than negative trends in meta-population metrics," that (2,3) they "did not find evidence that the probability of colonization or persistence increases with temperature nor that extreme weather events are reflected in higher extinction risks." And, last of all, they report that (4) they "could not prove that weather extremes have visible and consistent negative effects on ectothermic species in the temperate northern hemisphere."

In further discussing these observations, Malinowska et al. say they "do not confirm the general prediction that increased weather variability imperils biodiversity." And they therefore conclude that (5) "weather extremes might not be ecologically relevant for the majority of species," and that (6) "populations might be buffered against weather variation (e.g. by habitat heterogeneity)," or that (7) "other factors might be masking the effects (e.g. availability and quality of habitat)."

And based on these several real-world observations, the five researchers conclude that weather extremes have less - or different - impacts on real-world meta-populations "than theory and models suggest."

Posted 20 March 2015