I compared the abundance and distribution of vascular plant species found in tortoise (Chelonoidis nigra) dung piles. A total of 228 dung piles were sampled along an altitudinal gradient of 0-400m covering three vegetation zones of Santa Cruz Island, Galapagos, Ecuador. At least 68 non-grass species are eaten and dispersed by tortoises. Potential range extension through long distance dispersal was found in all common vascular plant species dispersed by tortoises. Additionally, each the current and future climatic suitability of two invasive plant species dispersed by tortoises was modeled with Maxent under two different climate change scenarios for 2050 and 2070. Results suggest a potential range shift under climate change in both test species, and a strong increase in suitability for Psidium guajava under both climate change scenarios for 2050 and 2070 alike. Common guava and its arrival to protected areas of the Galapagos National Park in Santa Cruz may be boosted due to long distance dispersal through Galapagos tortoises. Here I show an example of an endemic reptile enhancing the distribution of an invasive plant that is considered to be among the 100 worst invasive species. Eradication methods of these species will be harder under climate change and more advanced stages of invasion in the Galapagos archipelago.

Inglés