Is the ‘Lost World’ Lost? High Endemism of Aphibians and Reptiles on South American Tepuís in a Changing Climate

Abstract

The Pantepui region of the Guyana Shield of Northern South America harbors a unique biota. It is characterized by high local species endemism, especially applicable to its table mountain-like outcrops, the tepuis. For this region, also known as the ‘Lost World’, different hypotheses have been proposed to explain its Biogeography. We suggest that the amphibian and reptile communities’ suit well as target group to study the hypotheses since these vertebrates are relatively well documented through comprehensive species lists and are less mobile than other terrestrial vertebrates. However, records for the majority of endemic amphibian and reptile species naturally numbered only a few. We hence used extant dimensions of the vegetation zones associated to amphibians and reptiles. By running maximum entropy-based Climate Envelope Distribution Models (CEDM), these were projected to climatic scenarios as suggested for the Last Glacial Maximum (LGM, 21,000 years BP). Our results promote the Cool Climate hypothesis for diversity and distribution of amphibians and reptile communities in the Pantepui region, in which species’ geographic ranges were displaced followed by speciation along with the climate change during glacial-interglacial Quaternary cycles. Moreover, we studied the impact of expected future anthropogenic global warming on these vegetation zones. Climate change scenarios used, consider demographic, politico-economic, social and technological futures at different degrees with either more or less environmentally conscious, regionalized solutions to economic, social and environmental sustainability. For the ‘Lost World’, our CEDM results demonstrated a strong impact of climate change to vegetation zones resulting in a considerable decrease during future anthropogenic global warming in terms of habitat suitability. For amphibians and reptiles this may mean habitat loss and decline or extinction. However, nothing is known about specific climatic niche breadths (which may be great due to survival under climatic conditions with considerable daily change) or the possibility to adapt over generations (which may be unlikely due to the rapid warming expected) of Pantepui amphibians and reptiles. Further studies and monitoring efforts are necessary towards a better understanding of the problem and to develop conservation action plans.