To answer the first question, this MSCA project has finished the compilation of the world’s largest database on animals’ thermal tolerance to date and of the geographic thermal limits for these species. With these datasets, we have carried over a series of analyses to identify: : a) whether species’ heat tolerance restricts maximum environmental temperatures at each species’ known warm edges during the hottest time of the year (hereafter Tmax), using different estimates of heat tolerance and Tmax; b) whether Tmax values correlate across species’ geographic thermal limits; and, c) whether restrictions will be stronger for species whose thermal tolerance is more challenged by Tmax.
Heat tolerances, in so far measured, very often restrict the geographic thermal limits of animals (Ex. Fig. 1). Yet it does it heterogeneously, restriction is always stronger for those species that face higher temperatures for their tolerance, at their warm edges. In the figure, these taxa are represented by a red line, while species less challenged by high temperatures at their warm edges are represented by the orange and blue lines. Strikingly, reptiles appear as less geographically bound by their thermal tolerance than other taxa. Also, many fish have attained so high CTmax that free them from heat constrains on geographic distribution, contributing to a sigmoid relationship of CTmax with Tmax that contrast with terrestrial taxa. The relationships found undermine widespread practices for estimating shifts in species ranges and climatic vulnerability based on less useful parameters of thermal tolerance, or on purely geographic models.
Global patterns of heat restrictions on species geographic ranges should be refined once potential confounding factors can be further controlled (Ex. plasticity, local adaptation, biotic interactions), particularly for species groups and parameters that showed weaker correlations. For that, collecting further experimental data on heat tolerance at species’ geographic thermal limits remains paramount.
The second problem has been addressed comparing for the first time how different representations of thermal tolerance (different parameters of thermal tolerance versus a curve of time to death x temperature) could detect different geographic patterns in expected thermal vulnerability. These studies comprise:a) a North American lizard, analyzing how dehydration altered its thermal tolerance; b) the geography of thermal vulnerability for tropical ants and lizards, and, c) observing the timeframes of thermal acclimation in tropical tadpoles. The results of these studies suggest that the geography of estimations of thermal vulnerability are very sensitive to the parameter used and its intrinsic variability. Therefore, future reports on species’ thermal vulnerability must balance the need for a comprehensive representation of thermal tolerance, which is slow to obtain and stressful for the animals because it implies in more tolerance experiments for them, with the need of making useful predictions based on more practical and less stressful measures of thermal tolerance.
Finally, to make use of the gained understanding, and to disseminate robust and ethical methods to measure thermal tolerance, this project led to the creation of the VulneraWeb platform (www.vulneraweb.com). This is an online collaborative platform that uses supercomputing power provided by CSIC’s Finis Terrae III facility (
https://www.cesga.es/cesga/el-cesga/(se abrirá en una nueva ventana)) to map climatically vulnerable animal populations from all across the world (ex. Fig. 2). Different aspects of the problem of species’ vulnerability to climate change and the capabilities of the platform have been showed both in person and online from local to international scales through talks for schools, international online seminars and congresses. The platform and its channels in Instagram (vulnerawebglobal) and Twitter (Vulneraweb) have been created and updated with news, with the participation of a gender balanced team of international students.
