Invasive species hit the Global South significantly harder than previously assumed
Study involving JLU corrects previous assumptions regarding invasive species and shows paths for a new international environmental policy to reduce species extinction
Nr. 109 • 24. Juli 2026 (deutsche Version hier)
Invasive alien species are one of the world's largest drivers of species extinction. However, previous global assessments of the geographical distribution of these damages suffered from a systematic "research bias": because significantly more research is conducted and documented in Global North countries such as North America and Europe, these areas also showed the highest numbers of invasive species and, consequently, the most damage reports. A new study involving Prof. Dr. Hanno Seebens, Professor of Modeling Biological Systems at Justus Liebig University Giessen (JLU) and the Senckenberg Society for Nature Research, now shows: in countries of the Global South, invasive species cause significantly higher damage than in the Global North. This is due to a combination of rapid economic growth and insufficient state governance. The study, which also involved researchers from Switzerland and the Czech Republic, has been published in the journal "Science."
Measuring damage instead of counting species
The international research team led by Prof. tit. Dr. Sven Bacher (University of Freiburg, Switzerland), Prof. Dr. Petr Pyšek (Czech Academy of Sciences), and Prof. Seebens used a new methodological approach: instead of merely counting the presence of the invasive species, the scientists developed a new metric, the "average impact severity". This indicator relates the number of severe impacts – such as the local extinction of native populations – to all reported local ecological impacts. This makes the indicator independent of "research bias." The basis of the work is the new database "Global Impacts Dataset of Invasive Alien Species (GIDIAS)," which comprises over 22,000 documented impacts of invasive species in 172 countries.
The result is a scientific correction of previous assumptions regarding the consequences of invasive species: while the absolute number of reported species and reports is high in the Global North, the relative severity of the impact is significantly more pronounced in the Global South. "This is even evident in individual species," explains Prof. Seebens. "Invasive species that cause damage in both the Global South and the Global North do 50% more harm in countries of the Global South compared to countries of the Global North. Particularly in emerging economies of South America, Africa, and Asia, invasions more frequently lead to catastrophic ecological consequences."
Emerging economies particularly affected
The study also provides an explanation for this phenomenon, which primarily affects emerging economies: these countries experience high economic growth and intensive global trade, which massively accelerates the introduction of new invasive species. At the same time, they often have less developed state structures, higher corruption rates, and lower capacities in the management of biological invasions.
"While countries of the Global North do have many invasive species, intensive ecosystem management prevents them from having massive impacts," says Prof. Bacher, lead author of the study. "In contrast, the rising economic potential of emerging economies acts as an accelerator for the introduction of invasive species, while the institutional ability to respond lags behind." Using complex statistical models, the study shows that good governance and proactive management can effectively reduce the severity of biological invasions. In countries of the Global South, these mechanisms are often lacking, which allows invasive species to cause devastating ecological damage unchecked.
Consequences for international environmental policy
The results of the study have far-reaching consequences for international environmental policy. "Prevention is the most efficient way to prevent the consequences of invasive species, but this requires effective management structures in every country and intensive international cooperation," emphasizes Prof. Bacher. "If we want to overcome the global biodiversity crisis, we must close the management gap between North and South and stop marginalizing the regions most affected by invasive species." The researchers point out that it is not enough to monitor the spread of species globally. "We must not allow the environmental damage in regions of the Global South – many of which are home to the greatest biodiversity – to become irreversible," says Prof. Seebens.
Publication
Sven Bacher et al.: Invasive species’ environmental impacts are more severe in the Global South. Science393, 376-380 (2026)
https://doi.org/10.1126/science.aed0603
Kontakt
Prof. Dr. Hanno Seebens
Institut für Bioinformatik und Systembiologie
Telefon: 0641 99-35726
E-Mail: hanno.seebens
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