How will mammals respond to climate change?

As the ramifications of climate change become increasingly more apparent, our understanding of its complex impacts on mammals still has major gaps, according to a comprehensive review published in the Journal of Animal Ecology.

According to lead author Maria Paniw from Switzerland’s University of Zurich, changing climates affect animals in myriad ways, but this complexity has only been considered for less than 1% of all mammal species, impeding efforts to protect them.

“Assessments of the fate of natural mammal populations under climate change need to account for multiple demographic responses,” Paniw explains.

“We need to prioritise more holistic approaches and data collection, or integration, to understand the mechanisms that drive population persistence for evidence-based conservation.”

Climate change doesn’t always threaten natural populations, according to the review – impacts can be positive or negative depending on the life-cycle stage or the ecological context, giving animals some flexibility in how they respond.

This applies particularly to the divergence between survival and reproduction, for which the researchers found the effects were highly context dependent.

“So, say, a negative effect of higher temperatures on the number of offspring does not necessarily affect population size if having fewer offspring is compensated by higher survival of the remaining offspring,” says Paniw.

Despite this complexity, her team, which included 15 researchers across Europe, Australia and the US, discovered that most studies reported results on one or the other. Only 106 studies modelled both survival and reproduction at the same time as a function of climate variables such as temperature and rainfall, covering just 87 out of 5728 species reviewed.

There was a particular dearth of research on regions most sensitive to climate-driven extinction, such as those in high altitudes.

“Worse yet, we know very little about this complexity in the most climate-vulnerable regions of the globe,” says Paniw. “In our review, we had a few alpine species, such as yellow-bellied marmots and plateau pikas, but I was expecting a study or two on iconic species such as snow leopards.”

Many of the most vulnerable regions are hotspots for biodiversity, according to the review, and are further stressed by human activities.

The researchers say the knowledge gaps likely apply to other animal groups such as insects and amphibians, which are far less well-studied than mammals yet also vulnerable in the face of the Earth’s unfolding mass extinction.

Acknowledging the importance of the work that has been done, they call for greater collaboration to get a better grasp of animals’ plight. Paniw concludes: “Perhaps our review can give another perspective to support the argument that we need ‘more boots on the ground’, if we want to understand the mechanisms that drive biodiversity change in the Anthropocene.”

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