Introduction effort, climate matching and species traits as predictors of global establishment success in non-native reptiles

Abstract

Aim: Non-native reptiles are often detrimental to native communities and ecosystems and can be extremely difficult to manage once established. Thus, there is considerable interest in predicting the likelihood of establishment of non-native reptiles. We assessed three hypotheses describing possible factors contributing to the successful establishment of introduced reptiles in an effort to better identify potential invaders. Location: Worldwide. Methods: Using a global invasion database (1307 introductions of 398 species) and Bayesian generalized linear mixed models, we tested the relative importance of event-level (e.g. propagule pressure), location-level (e.g. climate matching) and species-level (e.g. parthenogenesis) factors in reptile establishment success. Results: The factors that positively influenced establishment success included: (i) Event-level: longer time since initial introduction, greater number of introduction events and intentional introductions; (ii) Location-level: smaller differences in latitude between native and introduced ranges and the presence of native congeners in the introduced range; and (iii) Species-level: smaller body size, herbivores, larger native range size, parthenogenesis and high fecundity. Main conclusions: We found that location-level factors were most important in describing reptile establishment success, followed by event- and species-level factors, respectively. This pattern matches closely with what others have found in a variety of vertebrate taxa. However, the importance of species traits may be underestimated considering the insufficient knowledge of reptile life history within introduced ranges. Importantly, individual variables from all three hypotheses contributed to global reptile establishment. Managers should be especially cognizant of small herbivorous and fecund reptiles that are frequently introduced into areas with a strong climate match to their native range. Further, parthenogenesis greatly facilitated establishment, indicating that obligate parthenogenetic species may become ubiquitous through modern globalized trade.