Human-introduced non-native species are a significant factor in the decline of global biodiversity, contributing to about 60 percent of recent extinctions worldwide. In Central Europe, some of these non-native mammals include the Norway rat, mouflon, and mink. A recent study conducted by researchers from the University of Vienna and La Sapienza University in Rome indicates that several of these non-native species are actually endangered in their places of origin. This research was published in the latest issue of the journal Conservation Letters.
The ongoing globalization of our planet is leading to the introduction of various animal and plant species into new environments. These invasive species often outcompete native species or introduce new diseases. Interestingly, some non-native species are themselves at risk of extinction in their native habitats. This situation creates a conservation dilemma: Should we protect or manage non-native populations of species that are endangered in their original environments? Until now, it was unclear how many non-native mammal species fell into this category. The new study aims to clarify this issue and provide insights into the paradox.
Many non-native mammal species face threats in their original habitats
Currently, a total of 230 non-native mammal species have been introduced by humans to various locations around the globe, where they have established permanent populations. “We were curious to determine how many of these species are threatened in their native ranges,” stated Lisa Tedeschi from La Sapienza University and the University of Vienna, who led the study. The researchers found that 36 of these non-native mammals are endangered in their original habitats, confirming the existence of this conservation paradox. “We were taken aback by this high number, as we expected that invasive species were prevalent in their native regions as well,” Tedeschi added.
Invasive species may help avert extinction for some
A notable example of a mammal under threat in its natural environment is the crested macaque, whose population on Sulawesi has diminished by 85 percent since 1978, even as it has established stable populations on neighboring islands. Similarly, the wild rabbit is endangered in Europe, yet in places like Australia, introduced populations far exceed those in Europe. Many of the threatened species in their native habitats originate from tropical Asia, primarily due to extensive deforestation and overhunting. Thus, these introduced populations might play a crucial role in helping some species avoid extinction.
The challenges for conservation in the age of globalization
When evaluating the global risk of extinction, non-native populations are typically not considered. The findings from this study reveal that the conservation status of certain species could improve if non-native populations were factored in. “For 22 percent of the species we analyzed, acknowledging non-native occurrences would decrease their global extinction risk,” explained Franz Essl, a biodiversity researcher from the University of Vienna and a co-author of the study. This underscores the significant role of non-native populations in conserving endangered species, particularly where native habitats are under severe threat.
However, the inclusion of non-native populations in threat assessments comes with drawbacks, such as the potential neglect of endangered native populations. Additionally, non-native populations may adversely affect other species. “Our primary focus should continue to be on the preservation of species in their native habitats. Nonetheless, as time progresses, more species may face endangerment in their original ranges while thriving in new environments. This presents a complex challenge for conservationists, who must balance the advantages and disadvantages,” concluded Franz Essl. “This is a reflection of how globalization influences species distribution.”
