Conservationists should focus on populations, not species, report finds

There could be wider variations in temperature tolerance, even within animals of the same species, a new report has revealed.

The findings offer conservationists optimism, as the scientific consensus is that the climate crisis is pushing the world into its ‘sixth extinction’ event, where species are going extinct 10,000 times faster than before the industrial era.

Scientists have been struggling to identify which species are most at risk of rising temperatures and research published in Nature Climate Change suggests a way forward could be focusing on populations rather than species.

‘One of the most important biological discoveries in the last century is that evolution can happen much more quickly than previously thought,’ explained Brian Cheng, professor of marine ecology at the University of Massachusetts Amherst and the paper’s senior author. ‘One of the implications of this is that different populations of the exact same species can adapt to their local environments more readily than traditional biology would have thought possible.’

Data on 61 species was collected from a metanalysis of 90 published studies to allow scientists to construct ‘upper thermal limits’ – specific temperatures above which each species could not survive.

The team then looked at 305 populations from the pool of species and found different populations of the same marine species had widely differing thermal limits. This suggests populations have evolved differently to high temperatures.

It’s thought that keeping different populations of the same species connected could ensure better adapted populations can pass on their advantage to populations with lower thermal limits.

‘Scale matters,’ says Matthew Sasaki, a marine biologist and evolutionary ecologist and lead author of the study. ‘The patterns you see across species aren’t the same you see within species, and the big-picture story doesn’t necessarily match what is happening on the local level.’

Additionally, researchers discovered this intra-species variability was most common among of marine animals, as animal populations living on land or in freshwater habitats had more similar thermal limits.

This means they could be more sensitive to temperature rises, but they do have better access to shade to cool down and avoid extreme temperatures.

Authors of the study suggest a better understanding of differences between populations of the same species is needed for a more effective approach to conservation. On the other hand, patches of microclimates, such as forests, could offer protect terrestrial animals from extreme heat.

Photo by Sebastian Pena Lambarri