No, I don’t mean a slurry of slugs and snails. I’m talking about spatial homogenization of biodiversity on a global scale. Capinha et al. (2015) just got a paper in Science (good for them!) reporting global distributions of native and non-native gastropods (Title: The dispersal of alien species redefines biogeography in the Anthropocene). The results are stark.
The image above, Fig 2 from Capinha et al. (2015), shows how species composition changes with distance for species in their native ranges (A) and in their current ranges (B). Native ranges were determined by comparing records human introductions from 1500CE to present with current distributions. If there was no record post-1500CE of a given species being introduced to a region, but the species is found there, then this region is considered to be part of the native range. This is a clever method for generating a conservative estimate of native status. It’s a conservative estimate because there are probably a lot of introduced species that were never reported as such.
What’s the Anthropocene? Read this.