Urban herpetofaunal assemblages: The value of novel ecosystems for conservation
Urbanization is the dominant trend of land transformation around the world. It replaces natural habitats with urban infrastructure and can reduce the diversity and abundance of native plant and animal communities, and also create new communities. Often those novel communities are the result of introductions and establishment of exotic, and domesticated plants and animals. The capacity of novel ecosystems to sustain wild populations from different groups, including reptiles and amphibians, is not well understood. However, studies around the world show that urban habitats can sustain substantial biodiversity. Currently, the herpetofauna is considered as the most threatened vertebrate group worldwide. Based on these premises, our study approached the following topics related with the effect of urbanization on herpetofaunal diversity in an island ecosystem: 1) what are the species‘ responses to variables acting in the habitat at the local-level, and 2) how they interact to maintain diverse assemblages in the landscape. We selected 30 study sites distributed in suburban and urban areas representing five (5) land covers (mature forest, young forest, shrubland, pasture, and yard) in the northeast of Puerto Rico.
Between November 2011 and October 2012 we observed 25 species representing 96.15% of the potential species for the study area. Twenty one (21) of them corresponded to native species. We recorded a new, exotic snake species for Puerto Rico, and the Western Hemisphere (Xenochrophis vittatus) in suburban and urban areas. The presence of terrestrial herpetofauna in the study area was the result of process occurring at different levels. At local-level, habitat structural complexity was the most important for the occurrence of species. At regional level, differences in species ability to respond at the effects of urbanization probably generate differences in the assemblage structure between areas. It means that some species were better represented in some habitats than other based on the different responses that species exhibit to the urbanization. Our results support the idea that novel ecosystems sustain high biodiversity and highlight the importance of urban systems for conservation. This information contribute to improve our capacity to understand the dynamics of biotic assemblages in urban ecosystems, and it can be used by conservation managers and planners to conserve biodiversity in the urban scenery.