Focus on populations, not species, to protect nature

Rapid climate change is placing significant stress on many of our planet’s plants and animals. In fact, many scientists argue that we are currently in the midst of the sixth mass extinction, with entire species disappearing up 10,000 times faster than before the industrial era. However, experts have been uncertain which ecosystems and species are most at risk. 

According to a new study led by the University of Massachusetts, Amherst, the focus on species-level risk obscures a wide variability in temperature tolerance, even within the same species. Moreover, this variability appears to be greater for marine species than for terrestrial ones. These findings have important implications for conservation and management practices and offer a window of hope in our effort to adapt to a rapidly warming world.

“One of the most important biological discoveries in the last century is that evolution can happen much more quickly than previously thought,” said study senior author Brian Cheng, a professor of Marine Ecology at UMass Amherst. “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.”

By conducting a metanalysis of 90 previous studies, the scientists collected data on 61 animal species, and constructed a set of “upper thermal limits,” or specific temperatures above which each species could not survive. Yet, by zooming in further and identifying 305 distinct populations drawn from these species, the experts were surprised to find that different populations of the same species often had highly different thermal limits, particularly in the case of marine wildlife. 

However, although terrestrial species appear to exhibit far more homogeneity in their thermal limits – and thus may be more sensitive to rising temperatures – they can nevertheless take advantage on microclimates to avoid extreme temperatures and cool down, such as by moving into shady areas.

These discoveries suggests that some populations have evolved different abilities to tolerate high temperatures. Thus, a key aspect of conservation practices would be to keep different populations of the same species connected, in order for those that have adapted to higher temperatures to pass this advantage on to populations with lower thermal limits.

Taken together, these findings show that a one-size-fits-all species-focused approach to conservation and management will most likely not work. Instead, in order to predict their vulnerability to changing conditions, we have to understand how populations have adapted to their local environments. “The glimmer of hope here is that with conservation policies tailored to individual populations, we can buy them time to adapt to the warming world,” Cheng concluded.

The study is published in the journal Nature Climate Change.

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By Andrei Ionescu, Earth.com Staff Writer

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