Stable population trends are a prerequisite for species' range expansion, according to new research led by scientists at the University of York.
The climate in Britain has warmed over the last four decades, and many species, including butterflies, have shifted their distributions northwards. The extent of distribution changes has varied greatly among species, however, with some showing rapid expansion and others showing none at all. But this variation can be explained by taking into account the abundance trends of species.
The study by researchers in Department of Biology at York, Butterfly Conservation and the Natural Environment Research Council (NERC) Centre for Ecology and Hydrology showed that butterflies were able to expand their distributions only if they had stable (or increasing) abundance trends. It is published by Nature Climate Change.
For those species with stable or increasing population trends that have been expanding their distributions, the amount of suitable habitat available in the landscape is important. The more habitat that is available, the faster a species can expand its distribution area.
Using data on butterfly distributions and abundances, collected by members of the public since the 1970s through 'citizen science' schemes, Louise Mair, a PhD student in Biology at York, and her colleagues examined factors limiting butterfly range expansion. These data reveal that species that were previously restricted to southern England are colonising northern England and Scotland. Butterflies have extended their distributions in this way because warmer climates have made northern regions increasingly more hospitable for these temperature-constrained insects.
The study concludes that conservation management must consider existing populations and ensure that species abundances are stable or increasing in order for them to be able to respond to climate change. Increasing the amount of natural habitat in the landscape is an
|Contact: David Garner|
University of York