Date Published: June 13, 2019
Publisher: Public Library of Science
Author(s): Miguel de Luis, Julio Álvarez-Jiménez, Juan Manuel Martínez Labarga, Carmen Bartolomé, Inés Ibáñez.
Climate change has altered the global distribution of many species. Accordingly, we have assessed here the potential shift in the distribution of Gypsophila bermejoi G. López under distinct scenarios of future climate change, this being a species endemic to the Iberian Peninsula. For strict gypsophiles, climatic changes affecting their potential area of distribution could be critical if the new range is not overlapped with suitable soils. Thus, the narrow bioclimatic niche and the endemic nature of this plant could make this species particularly vulnerable to climate change. We used the Maximum Entropy (MaxEnt) method to study the potential distribution of this taxon under four different scenarios of climate change, pin-pointing relevant changes in the potential distribution of this plant and enabling possible future areas of refuge to be assessed. Such scenarios are defined according to four Representative Concentration Pathways (RCPs) [, which represent different trends in the concentration of atmospheric carbon dioxide. As a result, we predict notable changes in the potential distribution of G. bermejoi, and the overlap between soil and bioclimatic suitability would be affected. We also used a Principal Component Analysis (PCA) to model the bioclimatic niche of this species, comparing it with that of its parental taxa. The evolution of bioclimatic suitability was assessed at the current locations of G. bermejoi and as this plant is a strict gypsophile, we generated suitability maps for sites with gypsum soils. Ultimately, this study identifies relevant changes in the potential distribution of G. bermejoi under specific climatic scenarios, observing remarkable differences in the outcomes of the different climate change scenarios. Interestingly, in some scenarios the bioclimatic suitability of G. bermejoi will be enhanced at many locations and even in the worst scenario some possible refuge areas were identified. G. bermejoi behaves more like a hardy survivor than as early victim.
The average global temperature has increased greatly over the last 100 years and a higher rate of warming has been projected in the future . Shifts in temperature have affected the habitats of a wide range of species  and accordingly, climate change has already altered the distribution of species in several regions around the world . Shifts in the range of some plant species have been highly significant, averaging 6.1 km per decade towards the poles, and a significant mean advancement of spring events by 2.3 days per decade has also been recorded .
The potential distribution of G. bermejoi was first obtained on the basis of the bioclimatic variables and later, we studied the suitability of the habitat at the sites where the soil favors these species. We did this for the current climatic conditions, and with the projections for 2050 and 2070. In order to locate suitable sites, we used data on the presence of Ononis tridentata L., a common and widespread species that lives on more or less pure gypsum soils and on gypsiferous loams [41,42].
From the MaxEnt models generated for the species studied, the AUC value obtained was 0.965, high enough to validate the models. The TSS value for the same species was 0.810, with values above 0.6 considered to be good and those of 0.2–0.6 to be fair to moderate.
Unusual bedrock and special soil areas, like gypsum or serpentine outcrops, are given high priority for biodiversity conservation. From the point of view of biogeography, such habitats can be considered as edaphic archipelagos , and they can be seen as natural laboratories to study evolutionary and ecological processes . In addition, they harbor a large number of endemic taxa and rare species. When considering the conservation of these species and communities, it is crucial to assess possible shifts in the optimum climatic areas and the relationship of these changes to their suitable soils. In this study, we examined the evolution of bioclimatically suitable areas for G. bermejoi under four different scenarios of climate change. As for other species adapted to such specialized soils, if the bioclimatic suitability area does not overlap with the location of suitable soils, this species could be committed to extinction. As such, the bioclimatic niche of this plant was also considered, indicating that this plant has a narrower niche when compared to other closely related taxa, which could make it particularly vulnerable to climate changes. If so, this species should receive special attention in conservation programs. Nevertheless, we should stress that a proper assessment of the extinction risk for this species would require further studies and that this was not the goal of the present study.
From the results obtained, we can draw the following conclusions: