Phylogenetic diversity does not capture body size variation at risk in the world's mammals

Abstract

Mammals contribute to important ecosystem processes and services, but many mammalian species are threatened with extinction. We compare how global patterns in three measures of mammalian diversity-species richness, phylogenetic diversity (PD) and body mass variance (BMV)-would change if all currently threatened species were lost. Given that many facets of species' ecology and life history scale predictably with body mass, the BMV in a region roughly reflects the diversity of species' roles within ecosystems and so is a simple proxy for functional diversity (FD). PD is also often considered to be a proxy for FD, but our results suggest that BMV losses within ecoregions would be much more severe than losses of PD or species richness, and that its congruence with the latter two measures is low. Because of the disproportionate loss of large mammals, 65 per cent of ecoregions would lose significantly more BMV than under random extinction, while only 11 per cent would lose significantly more PD. Ecosystem consequences of these selective losses may be profound, especially throughout the tropics, but are not captured by PD. This low surrogacy stresses a need for conservation prioritization based on threatened trait diversity, and for conservation efforts to take an ecosystem perspective.

The future of evolutionary diversity in reef corals

“…Reductions in PD and PSV, as well as associated changes in tree shape, were compared with a null model of the same level of random species loss (1000 replicates) [36,43,44,73]. To quantify the declines in PD and PSV specifically, we computed the excess loss of each metric under the 'observed' scenario relative to random, as a percentage of the random result [74].…”

“…PD [4] was computed as the sum of all branch lengths of the phylogeny of species present in an ecoregion [44,66]. The second metric, PSV [39], estimates the degree of phylogenetic disparity (or the lack of evolutionary redundancy) among species by quantifying the variance of a hypothetical neutral trait that is shared by all species in an ecoregion (see also [41,42]).…”

“…However, PD may be a poor predictor of trait variation present in a region [44,45]. Because maintenance of traits and associated functional diversity is critical for the resilience of complex ecosystems such as coral reefs [24,46,47], we use the PSV metric, which might be a better proxy of functional variation under phylogenetic conservatism [48,49], to quantify the effects of species loss on evolutionary disparity of corals.…”

Phylogenetic and functional diversity in large carnivore assemblages

“…Unfortunately, there are still no unified metrics that includes all aspects of biodiversity [10], and the use of PD as a proxy for FD is not unequivocally supported [2,11,12]. Because it may not be possible to simultaneously optimize conservation of all aspects of biodiversity, it is important to recognize the value of each component.…”

Sex‐biased breeding dispersal is predicted by social environment in birds

“…To test phylogenetic signal in the sign of sex‐biased dispersal, we retrieved the values of λ from PGLS models and performed D ‐statistics, a further measure of the strength of phylogenetic signal, presented in Appendix S5. D provides a measure of the phylogenetic signal in a binary trait, calculated as the sum of changes in estimated nodal values of that trait along edges in a phylogeny (Fritz and Purvis, 2010). Specifically, D ‐test compares the observed D ‐value for a binary trait on a tree to the value of D found using an equal number of simulations considering each of two models: (1) phylogenetic randomness, where trait values are randomly permuted among the tips of the phylogeny ( D  = 1), and (2) Brownian threshold model, where a continuous trait evolved along the phylogeny following Brownian process and then converted to a binary trait using a threshold providing the relative prevalence of the observed trait ( D  = 0).…”