Broad-scale destruction of natural habitats, in particular tropical forest, overexploitation of natural resources, and competition with/predation by introduced species are the primary sources of terrestrial biodiversity loss. Since the 1970s the human population has doubled, leading to increased anthropogenic pressures that have caused the size of animal populations to fall by almost half. However, the relationship between human activities and species distribution and abundance is complex. Every species has a climatic niche, which is the set of large-scale precipitation and temperature conditions where that species occurs. The niche can reflect physiological tolerances to these climatic conditions (fundamental niche), but can also be influenced by other factors, such as biotic interactions or human activities (realized niche). The latter is usually measured through models that relate the geographical distribution of species with climate in a given time. This implies that, according to the factors limiting the distribution of species in the time interval considered, the modelled realized niche of a species can vary.
In this project I plan to collect historic (1970s) and current distributions of terrestrial mammals and use them as a basis for building the climatic niche of species. I will compare the two niches of each species to identify changes in their breadth. I will then identify the climatic areas lost to understand niche breadth change, and will use anthropogenic factors (e.g. land use change, change in human population density) as correlates of this change. This will enable me to understand which variables have been more important in shaping the climatic niche of species, thus allowing more accurate predictions of their future potential distribution. I will focus my analyses on mammals because they have greater availability of historical distribution data and show also the largest contractions in their distribution compared to other taxonomic groups.
The EU 2020 Biodiversity strategy and the Convention on Biological Diversity (CBD) share the targets of reversing the rate of decline of species and preventing their extinction by 2020. Since it is believed that future climatic changes will likely exacerbate the effects of direct human pressure on the environment (e.g. land use changes; Visconti et al. 2016), there is urgent need to identify optimal methods for preventing the extinction risk of species due to global change. This project will provide one such method, combining niche change modelling with statistical methods aimed at assessing the impacts of human pressures on niche breadth, and testing the efficiency of commonly used methods to project the climatic niche into the future. This project is novel in relying on information on recent changes in species realized niche to obtain more reliable projections in view of future climate change. The main novel concepts, approaches and methods that will be employed include:
- Integrating climate change risk assessments with macroecology. This project brings together information on past and current species distribution into one coherent approach, improving our understanding on the climatic tolerances of species and providing information on how human pressures have impacted niche breadth, in order to prevent their extinction when using socio-economic scenarios.
- Adding an important dimension to the global debate on climate change vulnerability assessments ¿ This project aims to understand the conditions in and species for which bioclimatic envelope models can be used to model the climatic niche of mammals. This will provide a solid basis, which relies on observed data, to project their niche also into the future and evaluate their ability to adapt to future climatic conditions.
- Promoting the implementation of proactive conservation policies. An improved knowledge of how risk to biodiversity can be prevented cost-effectively will allow anticipating future biodiversity decline, by exploring the potential effects of current policy decisions.
The goal of this project is to define an approach that minimises species vulnerability to climate change by maintaining adaptive capacity and reducing exposure where possible. The proposed project addresses risk in a multidisciplinary way, spanning macroecology and conservation biology on the one hand and providing good basis to use socio-economic scenarios on the other hand. An improved understanding of how risk to biodiversity can be prevented cost-effectively, and how vulnerability signals can be identified, will shed light on the potential future effects of current policy decisions. This is associated to analyses of human pressures (e.g. land-use and climate change), with links with disciplines such as agricultural science and forest science (which study the drivers of global change). Collaboration with scientists from these disciplines will be facilitated thanks to my involvement in multidisciplinary initiatives such as the ISIMIP (The Inter-Sectoral Impact Model Intercomparison Project).