Name: Nogueira J

Biodeserts supervisor: JC Brito

Co-supervisor: Rebelo H

Title: Historical biogeography and climate change: application of ecological niche-based models and GIS to the conservation of African elephants and giraffes

Institution: University of Porto

Status: Completed

 

Abstract

Ecologists believe that biodiversity is under the sixth great extinction wave. Whereas climate has had an important role in previous extinction events, human activities are now assuming the front row. The interactions between climate change and habitat fragmentation are enhancing concerns on future species distribution and abundance. Habitat fragmentation is affecting negatively species already under pressure by precluding movements and dispersal. The human-induced climate change is expected to force species to shift their ranges or to modify their physiology and seasonal behavior. Attempts to address some of these issues have relied on ecological niche based models (ENN). With the assumption of niche conservatism (stability of species niches requirements), this approach combines species occurrences with a series of environmental variables to predict habitat suitability across landscapes. Uncertainties and errors related with modeling procedures, algorithms and assumptions have been raising questions about the impact on modeling results. The existence of long historical records and interactions with humans make the African elephant and giraffe ideal species to address methodological and ecological issues. The main goal of this thesis was to compare the effects of modeling partial niches in predictions of future species distributions. Current and historical distributions were used to test four modeling approaches regarding their sensitivity to climate change predictions, and to infer the effects of human activities. Results revealed great modeling performance with the exception for the Ecological Niche Factor Analysis and the Generalized Linear Models. The niche evolution of modeled species exposed a decreased in the climatic space that was more evident in giraffes. Regardless of the dataset used, predictions under climate change revealed an increase in suitable area for elephants. The giraffe’s predicted suitable area evolves differently according to datasets. Projections from historical data suggest an augment in distribution while projections made based on current distribution suggest a decreased in suitable areas. This study enlightens biogeographic patterns and future suitable areas under climate change. It also emphasizes the effects of human activities in species distributions and the consequences, limitations and uncertainties when modeling partial niches.