Climate matching - the environmental similarity between the native and non-native region of an introduced species - is one of the main drivers of biological invasions. Climate matching assumes niche conservatism, which is the retention of a species ecological niche through time and space, and studies have pointed out that niche shifts are rare in biological invasion. However, propagule pressure also plays an important role in the establishment of introduced species. At larger spatial scales, species introductions seem to be associated with humans’ facilities and maritime ports could be one main global pathway for the transport species. Therefore, if maritime ports are the entry points for introduced species, the number of docked cargo ships could indicate an indirect measure of propagule pressure. Here, we evaluate the role of climate matching and introduction effort in the invasion process of introduced terrestrial vertebrates of Brazil. We used species distribution models to measure how similar the climate in the introduced region was to the species’ native region and, obtained data on the number of international cargo ships that docked at Brazilian ports between the years 2010 – 2017. If both hypotheses are important predictors in the successful establishment of introduced species, then we expect to find a positive association between suitability values (obtained from species distribution models) and the number of docked cargo ships along the coast of Brazil.
Results/Conclusions
We found a significant positive association between the number of docked cargo ships with mean environmental suitability (z = 3.863, p=0.0001, Pseudo R² = 0.47). Our results support the hypothesis that in the first stage of the invasion process both climate matching and introduction efforts are important for the establishment of introduced species. This is supported by the similar suitability values of the first location the species was detected and the closest port (W = 133, n1 = 16, n2 = 16, p = 0.864). Taken together, our results reinforce the interactive role of several ecological factors in the establishment of introduced species. Although, ports have been shown as important hubs for the introduction of aquatic organisms, our data also support the idea that ports are important entry points of terrestrial vertebrates. However, it is still necessary to untangle the role of propagule pressure and climate matching with the role of different pathways such airports, mail and other forms of transportation.