The conservative low‐phosphorus niche in Proteaceae

Abstract

Proteaceae are an ecologically distinctive family, with largest radiations in the sclerophyll vegetation types of Australia and South Africa. This brief paper comments on Hayes et al. (2021), who have mapped leaf phosphorus concentration on to the phylogenetic tree for the family. Considered across all seed plants worldwide, Proteaceae contribute most of the lowest leaf nitrogen (N) and phosphorus (P) concentrations known. Hayes et al. concluded that they have used low-phosphorus strategy from their origins ca. 100 My ago. Occasional excursions into higher leaf P have been relatively recent and have not produced many species. The family as a whole is an instance of phylogenetic niche conservatism. The conservatism arises not from trait inertia but from the intensity of competition in continental vegetation, giving Proteaceae competitive advantage within distinct niches and inhibiting them from radiating into other ways of life. When a distinct niche is concentrated into a single clade in this way, quantitative methods that test for replicate patterns across multiple clades will not detect strong signal. However, niche-conservative clades make important and distinctive contributions to the world’s ecology.