NON-NATIVE SPECIES: POTENTIAL SURVIVORS IN CHANGING CLIMATIC CONDITIONS

Conventional biological thought states that non-native species cause loss of biological diversity (genetic, species, and ecosystem diversity) and threaten the well-being of humans when they become invasive. However, recent studies have shown that not all non-native species cause biological or economic harm, and only a fraction become established and have an effect that is considered harmful. In some cases, however, this study shows that some exotics can also provide conservation benefits.

A subset of non-native species will undoubtedly continue to cause biological, economic, and social harm. But other non-native species could become increasingly appreciated for their tolerance and adaptability to novel ecological conditions and their contributions to ecosystem resilience and to future speciation events. A research paper by Schlaepfer and colleagues outlines their roles and advantages. The ways in which non-native species were found to contribute to conservation objectives were:

• By providing shelter and food for native species
• Catalysts for restoration
• As ecosystem engineers
• As ecosystem service providers
• By taxon substitution within ecosystems

Ecological roles in rapidly changing ecosystems

Non-native species are potential survivors of future climatic scenarios given their ability to tolerate and adapt to a broad range of biotic and abiotic conditions, as well as to expand their ranges rapidly. They can contribute to ecosystem resilience and stability. They can also be expected to contribute to some of the putative benefits of speciesrich ecosystems, such as increased productivity and stability.

Novel evolutionary lineages

Given sufficient time, non-native species can increase global species richness through speciation. Nonnative species can also contribute to the formation of novel evolutionary lineages among native species. They can also catalyse hybridisation events between native species that result in novel evolutionary lineages. Speciation events can also result from hybridis`ation between certain non-native and native species and between pairs of non-native species.

Thus, it becomes essential to manage non-native species well. The management of non-native species and their potential integration into conservation plans depends on how conservation goals are set in the future. A fraction of non-native species will continue to cause biological and economic damage, and substantial uncertainty surrounds the potential future effects of all non-native species. Nevertheless, the prediction is that the proportion of non-native species that is as benign or even desirable will slowly increase over time as their potential contributions to society and conservation become well recognised and realised.

Further reading:

Schlaepfer MA, Sax FD & JD Olden. 2011. The potential conservation value of non-native species. Conservation Biology 25(3):428-437.