Shifts in the timing of life cycle events – known as phenology - of interacting species, such as predator versus prey and plant versus pollinator, are often listed as a consequence of climate change.
New research by University of Ottawa professor Heather Kharouba shows that shifts in the relative timing between key biological events are greater in magnitude than before recent climate change began. This suggests that there will be widespread climate change-related shifts in the synchrony of species interactions in the future.
“We were able to show that on average the relative timing between key biological events, such as the date of first flower vs. when insects emerge in the spring, is different than it was before the early 1980s,” explains Dr. Kharouba.
Using a new global database they put together on the seasonal timing of biological events for pair-wise species interactions, Kharouba and colleagues compared changes in the relative timing of 54 interrelating species pairs, both terrestrial and aquatic, between 1951 and 2013. The authors found that on average, individual species shifted their phenology four days earlier per decade after 1981, compared to 2.7 days per decade before 1981. Synchrony between species pairs has changed on average from 0.97 days/decade pre-1981 to 6.1 days/decade post-1981.
“Changes at the bottom of the food chain could have a domino effect. For example, the relative timing of the blooms of unicellular plant-like organisms and microscopic animals at the bottom of Lake Washington, WA, US is now off by almost 34 days,” adds Dr. Kharouba.
Interestingly, for some pairs of species, there are now more days between events than there were 35 years ago whereas for other pairs, these events now occur closer together within a season.
“Yet, many questions remain: how is pollination going to be affected? Will there be more or fewer predators? I'm working on this question now,” concludes Kharouba.
The full research paper: Global shifts in the phenological synchrony of species interactions over recent decades is published in PNAS.
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