Functionally unique, specialised, and endangered (FUSE) species: towards integrated metrics for the conservation prioritisation toolbox

Abstract

Identifying species with disproportionate contributions to biodiversity can lead to effective conservation prioritisation. Despite well-established methods for identifying endangered species adding inordinately to evolutionary diversity, in this context functional diversity has been overlooked. Here, we compare different metrics designed to identify threatened species that contribute strongly to functional diversity. We use the diverse and threatened global marine megafauna as a case study. We found that functional contributions of species are not fully captured in a single metric. Although we found a very strong correlation between functional specialisation and distinctiveness, functional uniqueness was only moderately correlated with the other two metrics and identified a different set of top-10 species. These functional contributions were then integrated and combined with extinction risk to identify species that are both important contributors to functional diversity and endangered. For instance, the top-10 Functionally Unique Specialized and Endangered (FUSE) species contains three critically endangered, five endangered and two vulnerable species whichdespite comprising only 3% of species -are among the top 10% most functionally unique and hold 15% of the global functional richness. The FUSE index was remarkably robust to different mathematical formulations. Combining one or more facets of a species contribution to functional diversity with endangerment, such as with the FUSE index, adds to the toolbox for conservation prioritisation. Nevertheless, we discuss how these new tools must be handled with care alongside other metrics and information.

Loss of functional diversity through anthropogenic extinctions of island birds is not offset by biotic invasions

“…Our analyses suggest that anthropogenic extinctions tend to remove functionally distinctive species from island ecosystems and that the ecological impacts of these losses are only partially offset by anthropogenic species introductions. These findings support calls to focus conservation efforts ( 36 , 73 ) on preserving functionally distinct threatened species ( 65 , 73 ), an important step toward minimizing further erosion of unique ecological functions that underpin the diversity and resilience of ecosystems. More generally, our study highlights how emerging global datasets of functional traits offer a tool for assessing the impacts of species turnover in assemblages, particularly when traits can be estimated from living organisms and the fossil record.…”

Combined effects of bird extinctions and introductions in oceanic islands: Decreased functional diversity despite increased species richness

“…Functionally unique species have recently been considered key for effective conservation because they represent distinct ecological strategies and often have a disproportionally high extinction risk (Carmona et al., 2021; Griffin et al., 2020). However, in order to preserve the global diversity of ecological strategies, conservation efforts have to integrate complementary metrics, such as functional richness and functional uniqueness at multiple scales (Cooke et al., 2020).…”

Combined effects of bird extinctions and introductions in oceanic islands: decreased functional diversity despite increased species richness

“…Functionally unique species have recently been considered key for effective conservation because they represent distinct ecological strategies and often have disproportional higher extinction risk (Griffin et al, 2020; Carmona et al, 2021). However, in order to preserve the global diversity of ecological strategies, conservation efforts have to integrate complementary metrics, such as functional richness and functional uniqueness at multiple scales (Cooke et al, 2020).…”