Fire ant (Solenopsis invicta). Jesse Rorabaugh

One major environmental concern is the inability of native flora and fauna to shift their ranges quickly enough to keep up with rapid climate change, which increases the risk of species’ extinction. Many populations of non-native species already have advantages over native species. To explore this further, Spanish and American researchers have reviewed studies of more than 6,000 native and non-native species of flora and fauna, including observed (682 species of study) and modelled changes (5571 species of study) of their spread range.

This study, published in the journal Annual Review of Ecology, Evolution, and Systematics and with the participation of two institutes of the Spanish National Research Council (CSIC), concludes that non-native species are spreading their ranges faster than native species. This shows that humans contribute to the expansion of invasive species, favouring repetitive introductions within their new distribution range. In addition, invasive species could have traits that enable them to spread faster than native species.

Montserrat Vilà, Professor of Research in the Doñana Biological Station (EBD-CSIC), summarizes the results with these figures: “Spread rates due to human introductions are a 1000 bigger than natural spread rates of native species. Within the introduced range, non-native species can spread over 20 times faster than native species.”

In addition, they further showed that non-native species have larger potential ranges and range expansions with climate change, probably due to a combination of widespread introduction and broader climatic tolerances. Also, due to climate change, native species are projected to have a larger range contraction, leading non-native species to win more and lose less space than native ones. 

Clearly, with faster spread rates and a major potential to persist or expand, non-native species’ populations have a decisive advantage in a changing climate. It is an environmental alarm since many of these species cause important environmental and socioeconomic impacts in the reception ecosystems. Belinda Gallardo, tenured scientist in the Pyrenean Ecology Institute (IPE-CSIC) says: “As society, we often refuse the risks associated with the relocation of native species beyond their natural ranges in response to climate change, while we transport non-native species all over the world without any concern.”

“A greater focus on spread mechanisms would help us to identify vulnerable native species and non-native species with high risk of expansion due to climate change,” Vilà says.