Data from: Conserving phylogenetic diversity can be a poor strategy for conserving functional diversity

For decades, academic biologists have advocated for making conservation
decisions in light of evolutionary history. Specifically, they suggest
that policy makers should prioritize conserving phylogenetically diverse
assemblages. The most prominent argument is that conserving phylogenetic
diversity (PD) will also conserve diversity in traits and features
(functional diversity [FD]), which may be valuable for a number of
reasons. The claim that PD-maximized (“maxPD”) sets of taxa will also have
high FD is often taken at face value and in cases where researchers have
actually tested it, they have done so by measuring the phylogenetic signal
in ecologically important functional traits. The rationale is that if
traits closely mirror phylogeny, then saving the maxPD set of taxa will
tend to maximize FD and if traits do not have phylogenetic structure, then
saving the maxPD set of taxa will be no better at capturing FD than
criteria that ignore PD. Here, we suggest that measuring the phylogenetic
signal in traits is uninformative for evaluating the effectiveness of
using PD in conservation. We evolve traits under several different models
and, for the first time, directly compare the FD of a set of taxa that
maximize PD to the FD of a random set of the same size. Under many common
models of trait evolution and tree shapes, conserving the maxPD set of
taxa will conserve more FD than conserving a random set of the same size.
However, this result cannot be generalized to other classes of models. We
find that under biologically plausible scenarios, using PD to select
species can actually lead to less FD compared with a random set.
Critically, this can occur even when there is phylogenetic signal in the
traits. Predicting exactly when we expect using PD to be a good strategy
for conserving FD is challenging, as it depends on complex interactions
between tree shape and the assumptions of the evolutionary model.
Nonetheless, if our goal is to maintain trait diversity, the fact that
conserving taxa based on PD will not reliably conserve at least as much FD
as choosing randomly raises serious concerns about the general utility of
PD in conservation.