Global distribution and conservation status of ecologically rare mammal and bird species

Nicolas Loiseau,Cyrille Violle,Wilfried Thuiller,Maya Guéguen,Julien Renaud,Nicolas Casajus,David Mouillot,Laure Velez,Matthias Grenié,Caroline Tucker,Brian Maitner,Nicolas Mouquet,Annette Ostling

doi:10.1038/s41467-020-18779-w

Abstract

Identifying species that are both geographically restricted and functionally distinct, i.e. supporting rare traits and functions, is of prime importance given their risk of extinction and their potential contribution to ecosystem functioning. We use global species distributions and functional traits for birds and mammals to identify the ecologically rare species, understand their characteristics, and identify hotspots. We find that ecologically rare species are disproportionately represented in IUCN threatened categories, insufficiently covered by protected areas, and for some of them sensitive to current and future threats. While they are more abundant overall in countries with a low human development index, some countries with high human development index are also hotspots of ecological rarity, suggesting transboundary responsibility for their conservation. Altogether, these results state that more conservation emphasis should be given to ecological rarity given future environmental conditions and the need to sustain multiple ecosystem processes in the long-term.

Highlights

Identifying species that are both geographically restricted and functionally distinct, i.e. supporting rare traits and functions, is of prime importance given their risk of extinction and their potential contribution to ecosystem functioning
For a global assessment of ecological rarity, it is necessary to build the functional space of species worldwide based on their relative position in the Eltonian niche space[18,19,20] known as the trophic niche space, which focuses on traits related to biotic interactions and resource–consumer dynamics[21]
We found that the first axis (PC1) was not correlated to functional distinctiveness which was mostly explained by the second and third axes for mammals and by the second and fourth axes for birds

Summary

Introduction

Identifying species that are both geographically restricted and functionally distinct, i.e. supporting rare traits and functions, is of prime importance given their risk of extinction and their potential contribution to ecosystem functioning. We find that ecologically rare species are disproportionately represented in IUCN threatened categories, insufficiently covered by protected areas, and for some of them sensitive to current and future threats While they are more abundant overall in countries with a low human development index, some countries with high human development index are hotspots of ecological rarity, suggesting transboundary responsibility for their conservation. Recent findings showed that threatened birds and mammals are more functionally distinct than non-threatened species[14] Taken together these results call for a global assessment of both facets of rarity, which will be facilitated by the development of a theoretical corpus and associated methodology[13,15]

Methods

Results

Conclusion