Should species with smaller distribution ranges always be prioritised for conservation?

Results and Scripts related to the Paper "Should species with smaller distribution ranges always be prioritised for conservation?" submitted to the Journal Bodiversity and Conservation 

Abstract 

Alarming trend in biodiversity decline has been observed due to anthropogenic drivers, reinforcing the need to identify priority species for conservation. We discuss the prioritisation of species with small distribution sizes for conservation through two often-neglected perspectives: exposure to human-driven threats and importance to biodiversity. To evaluate species exposure, we estimated the amount of human pressure within their distribution ranges. To estimate species distinctive contributions to ecosystem functions and services, we calculated decreases in phylogenetic diversity after sequential species exclusion. We found that species with smaller distribution ranges are not the most exposed to human-driven threats, as phylogenetic diversity is not always affected by the loss of these species when compared to species with broader distribution ranges. We propose conservation strategies to cope better with species vulnerability and to identify species with higher conservation needs. Species undergoing high exposure to human-driven threats would benefit from conservation initiatives distinguishing the causes of smaller range size. Ecosystem management could focus on species whose distribution is mostly limited by abiotic suitability, while species management could be more adequate for species whose distribution is mostly limited by accessibility. We also discuss the use of a response–effect framework to improve our capacity to identify species more negatively impacted by human-driven threats and with more distinctive effects on ecosystem processes. Species with smaller distribution ranges should be prioritised for conservation when a negative correlation between species' ability to cope with environmental change and the distinctiveness of their effects on ecosystem processes is found.