Land use change and invasive species are two of the greatest threats to biodiversity and may interact to further threaten native biodiversity. South Florida (USA) has become the global hotspot for the introduction of non-native reptile and amphibian species and has experienced major land use change over the past century. Many non-native species that arrive in Florida persist and establish populations, while many native species are now seldom seen. Native species may be adapted to the specific and rare habitats of South Florida such as the Pine Rocklands, which have been reduced to 2% of their original extent. Miami-Dade County has established the Environmentally Endangered Lands (EEL) Program to protect remnant native habitats. To determine whether native herpetofauna are persisting in areas where native habitat is preserved, we conducted visual encounter surveys for reptiles and amphibians in 15 native and 15 non-native parks. Native and non-native parks varied in size while spanning similar areas, and both covered the same geographic area in Miami-Dade County.
Results/Conclusions
Less than 10% of the individuals that we recorded were native, and we found no difference in the relative abundance or richness of native species between native and non-native parks (P = 0.28 and P = 0.31, respectively). Community analyses indicate that only 9% of the total variance in herpetofaunal community composition is between native and non-native parks (P = 0.0002), and that even this difference is driven by non-native species, with brahminy blind snake (Ramphotyphlops braminus), the most widely introduced species of snake in the world, being the best indicator of native habitat patches (P = 0.0094), and two invasive lizards from the Caribbean (Anolis sagrei and A. equestris) being the best indicator of non-native habitat (P = 0.041 and P = 0.0058, respectively). These results demonstrate that non-native reptiles and amphibians dominate both non-native and native habitat patches in Miami-Dade County. These findings could be the result of non-native species outcompeting native species even within native habitats. Alternatively, as non-natives have previously been demonstrated to dominate in altered ecosystems, these results could be due to a continuous influx of non-native species into native habitat from the surrounding urban matrix.