Quantifying Global Colonization Pressures of Alien Vertebrates in Trade

Abstract

The increased trade in live wildlife for pets and other uses potentially elevates colonization pressure, and hence the risk of invasions. Yet, we have limited knowledge on number of species traded outside their native ranges as aliens. We create the most comprehensive global live terrestrial vertebrate trade database, and use it to investigate the richness of alien species in trade, and correlates of establishment richness, for aliens across countries worldwide. We identify 10,378 terrestrial vertebrate species in the live wildlife trade globally. Approximately 90.1% of these species are aliens, and 9.1% of the aliens establish populations. Large numbers of alien species have been imported to countries with high incomes and large areas. Such countries are also hotspots for establishment, along with some island nations. Colonization pressure and insularity consistently promote establishment richness across countries. Socio-economic and climatic factors are also associated with establishment richness for different taxa. This study identifies daunting challenges to global biosecurity from future invasion risks posed by wildlife trade.

Elevated human impact on islands increases the introduction and extinction status of native insular reptiles

“…Viviparous species were neither less-prone to extinction nor more likely to be introduced. The effect of clutch size on introductions is likely accentuated by the pet and wildlife trade (Li et al 2023). Pet breeders focus on species who reproduce more, and pet introductions are a major invasion pathway for squamates (Perella & Behm 2020; Stringham & Lockwood 2018).…”

“…Islands have consistently been found to have more established alien species than the mainland (e.g., Li et al 2023). What we found here was that islands also generate more introduced species than the mainland.…”