The most effective conservation strategies for protecting vertebrates on a global scale are those aimed at mitigating the effects of overexploitation, habitat loss and climate change, which are the most widespread threats with the greatest impact across the planet. This is one of the main conclusions of an article led by researchers Pol Capdevila, from the Faculty of Biology and the Biodiversity Research Institute (IRBio) at the University of Barcelona, and Duncan O’Brien, from the University of Bristol (United Kingdom).
The study, published in the journal Science Advances, highlights the importance of climate policies in reversing biodiversity loss across the planet, and points to amphibians as the group of vertebrates particularly affected by the combined effects of multiple threats.
Interestingly, the study points out that populations affected solely by habitat loss or exploitation do not show the most pronounced declines. “The decline in vertebrate populations is much faster when they face several simultaneous threats (disease, invasive species, pollution or climate change, etc.) than when they are exposed to just one,” says Pol Capdevila, lead author of the article and member of the Department of Evolutionary Biology, Ecology and Environmental Sciences at the UB.
“However, in the study we also show that to shift biodiversity trends from negative to positive, conservation strategies must address multiple threats simultaneously,” says the author.
A paradigm shift from the more traditional view
The study is based on the analysis of 3,129 time series of vertebrate populations distributed across all continents and across the three systems (freshwater, marine and terrestrial). The conclusions indicate that these threats generally add to each other’s impact, rather than multiplying it.
This study represents a turning point from the traditional perspective on threats to vertebrates, particularly in three main aspects. “Firstly, the most frequent threats (habitat loss and overexploitation) are not those that cause the most rapid declines,” says Capdevila.
“Traditionally, habitat loss and exploitation have been considered the main causes of the biodiversity crisis because they are the most prevalent. However, our results indicate that biological invasions, diseases, pollution and climate change are associated with faster population declines than these more classic threats.”
The study also shows that interactions between threats are more decisive than spatial or temporal variability. “We also demonstrate that the combination of several pressures contributes more to population decline than other factors such as spatial or temporal autocorrelation, reinforcing the idea that multiple impacts are essential in the current loss of biodiversity.”
Furthermore, conservation focused on a single threat is insufficient. “The results also show that focusing efforts on reducing a single threat would not reverse the global decline of vertebrates. Only the simultaneous mitigation of multiple threats can bring population trends to non-negative values,” concludes the researcher.