Plant and animal populations, including humans, show strong seasonal cycles in health, behaviour and abundance, but these “rhythms of life” are being disrupted, reports a study published today (14 October 2015) in the journal Proceedings of the Royal Society B.

The paper, led by researchers at the University of Aberdeen and Glasgow, resulted from international collaboration between 26 universities and research institutes across the UK, continental Europe, United States, Australia, India and Japan. CEH scientists Dr Stephen Thackeray and Dr Alistair Dawson were part of the cross-disciplinary “Seasons of Life” initiative of the University of Glasgow, established to address the major challenges posed by environmental change to human and ecosystem health.

Parus major, great tit, on a branchBy bringing together examples from different terrestrial and aquatic ecosystems, including birds such as great tits (pictured right), the authors document widespread evidence of seasonality in physiology and behaviour ranging from birth and death rates in humans, to breeding success and immunity in wild species such as birds and grazing mammals. They highlight growing evidence that disruptions to these seasonal rhythms imposed by environmental change have negative health impacts.

Contributing author Dr Stephen Thackeray from the Centre for Ecology & Hydrology (CEH) said, “There is mounting evidence that the ecological seasons are changing, and so we must prioritise research into the possible impacts that these changes have. We need to know the extent to which species are resilient, or vulnerable, to seasonal disruption.”

Contributing author Dr Alistair Dawson of CEH said, “All species on our planet have co-evolved in environments that change seasonally during the year. Their life cycles are finely tuned to adapt to, and benefit from, seasonality. The potential impacts of anthropogenic disruption of seasonality on ecosystems are wide-ranging, complex and little understood.”

Uniquely, the study complements findings from ecosystems and physiology by assessing the impact of disrupted seasons on the spread of infectious diseases to people, livestock and wildlife.

Humans may also be directly affected by disrupted seasonal cycles. The disruption of ancient seasonal rhythms by life-style changes has disconnected us from seasonal variations in the natural environment, buffering us within a state of “eternal summer”. Furthermore, we are all dependent upon natural seasonal cycles that are critical to the production of food by agriculture and fisheries.

"The potential impacts of anthropogenic disruption of seasonality on ecosystems are wide-ranging, complex and little understood.” Dr Alistair Dawson, CEH

Lead author Dr Tyler Stevenson, of the University of Aberdeen, said that “the collective nature of our work highlights that humans are not simply passive responders to seasonal climates, and the challenges we face now are in identifying how humans and other animals maintain seasonal time at a genetic level”.

This research shows that seasonal disruption is a common challenge that faces human and wild plant and animal populations alike. To meet this challenge, there is a clear need to work across disciplines to fully understand the impacts of seasonal disruption, and the extent to which we can adapt to change.

Additional information

The University of Glasgow issued a press release for this story.

Full paper reference: Disrupted seasonal biology impacts health, food security and ecosystems, Royal Society Proceedings B, 2015, T J Stevenson et al. doi: 10.1098/rspb.2015.1453 (open access)

Dr Stephen Thackeray led the Shifting Seasons & ecosystem consequences project at CEH

Staff page of Dr Stephen Thackeray