The massive losses predicted have also been found by previous scientific work. For desert species this may be explained by many already living at or near their upper thermal limits, meaning they can’t adapt to even more extreme temperatures.
Range losses
For birds, the most vulnerable class predicted by my results, prior research found a much higher “cooling cost” (i.e. amount of water required for evaporative cooling of the body to maintain homeothermy) than for mammals, as well as climate warming having a bigger impact on this cooling cost in birds. This could explain why they were predicted to lose the most range. However, other work argued that they exhibit characteristics with the capacity to disperse and colonise remaining suitable habitat. Although research previously concluded small mammals to be one of the most vulnerable functional groups in their work, small mammals are known to tolerate high internal and external temperatures. Reptiles tend to have small home ranges, small body sizes, low adaptive capacities, and are highly sensitive to temperature changes as ecotherms. Such previous research explains why I found birds to be most vulnerable, followed by the reptiles, and mammals to be least vulnerable.
The difference found between threatened and non-threatened species are likely due to the lack of research of Saharan biodiversity, as many are still considered unevaluated and data-deficient. Nonetheless, predictive models with the limited available data could be an effective tool to forecast potential changes in threat level of species, allowing for reevaluation and increased pressure for conservation action.
Flagship species showed overall higher species richness and suitability across the Sahara than non-flagships. This suggests that conservation monitoring focused on flagships alone may underestimate the overall ecosystem effects. However, the average spatial differences in risk to losing suitability was marginally different, as were the trend of range loss in percentage. With limited funding and resources available for monitoring, the use of flagships as an overall representation of the ecosystem doesn’t appear to be detrimental for non-flagship species.
Potential refugia
Spatially, birds were largely restricted to the coasts, whereas reptiles and mammals were also found all across the northern Sahara and, to a lesser extent, the mountain ranges. The higher maintained suitability and richness along the coasts is likely due to the “oceanic buffering effect”, which results in somewhat milder conditions and more humidity, allowing for higher productivity. Additionally, these areas are pary of major migratory routes, including the Atlantic corridor and Red Sea corridor. Indeed, corridors are hugely important for dispersal of species, in order to colonise new habitats, but also for finding food and mates.
However, the rising sea-levels and increasing human presence and pressures (incl. urbanisation, off-shore wind farms, fishing and overhunting) at the coasts are still likely to impact the leftover suitable habitat in the areas. In addition, these areas still lack widespread protection and have suffered from long periods of armed conflict, which continue to threaten local biodiversity and the effectiveness of the few existing protected areas.
As my work showed differences in threats between the classes, conservation planning ought to consider the areas of importance for the specific groups and response of individual species in question, especially the more vulnerable ones, rather than using an average of the community.
Conclusion
My work predicted Saharan biodiversity to be under great threat to future range losses, with predicted refugia still underprotected. I concluded that a focus of flagships in conservation planning could act as great tool to increase the effectiveness of conservation efforts in the Sahara, though this is depends on the specific area and does require increased monitoring of Saharan flagships. Overall, I conclude a need, and advocate, for more protected areas, specifically at the Atlantic and Red Sea coasts.