Species Turnover is Slowing, Not Speeding Up, New Study Suggests
A groundbreaking study by Queen Mary University of London researchers, published in Nature Communications, challenges a widely held ecological hypothesis. Contrary to expectations that global warming would accelerate changes in nature, the research indicates that species turnover in local habitats is actually slowing down. Ecologists have often theorized that rising global temperatures would lead to faster rates of species extinction and colonization in new areas.
The study analyzed a vast database of biodiversity surveys spanning marine, freshwater, and terrestrial ecosystems over the last century, revealing a significant deceleration in species turnover.
Dr. Emmanuel Nwankwo, the lead author, starkly described the finding: "Nature functions like a self-repairing engine, constantly swapping out old parts for new ones. But we found this engine is now grinding to a halt."
Key Findings from the Research
The research meticulously focused on the period since the 1970s, a time marked by a notable acceleration in global surface temperatures and environmental shifts. Researchers compared species turnover rates—the speed at which species replace one another—both before and after this intensified climate change era.
Data consistently showed that turnover over 1-5 year periods tended to become slower across various environments. This deceleration was evident in diverse ecosystems, from terrestrial bird communities to the seabed. Professor Axel Rossberg, a co-author, highlighted the extent of this trend, noting that turnover rates typically declined by one third.
The researchers propose that ecosystems are not merely passive reactors to external climate drivers. Instead, they appear to operate in a "Multiple Attractors" phase. This theoretical state, predicted by physicist Guy Bunin in 2017, describes how species continuously replace one another due to internal interactions, even without direct environmental changes. This study now provides compelling empirical evidence for this complex ecological phase.
Understanding the Implications of the Slowdown
The authors suggest that the observed deceleration in species turnover is a direct consequence of environmental degradation and the reduction of regional species pools. In a healthy "Multiple Attractors phase" ecosystem, a large reservoir of potential colonizers is crucial for supporting robust species turnover.
"However, human activity is thought to degrade habitats and reduce these regional pools, thereby critically slowing the rate at which species replace one another."
Dr. Nwankwo further commented on the human element, stating, "In other research we are seeing clear indications that human impacts cause the slowing of turnover. It is worrying." The study's critical conclusion is that a lack of observed change in local species composition should not be misinterpreted as a sign of stability or ecosystem health. Instead, this widespread slowdown may be a grave indicator of a loss of momentum in biodiversity due to the depletion of regional life.