Time‐calibrated phylogeny of the woody Australian genus Hakea (Proteaceae) supports multiple origins of insect‐pollination among bird‐pollinated ancestors

Abstract

A past study based on morphological data alone showed that the means by which plants of the Australian genus Hakea reduce florivory is related to the evolution of bird pollination. For example, bird pollination was shown to have arisen only in insect-pollinated lineages that already produced greater amounts of floral cyanide, a feature that reduces florivory. We examine a central conclusion of that study, and a common assumption in the literature, that bird pollination arose in insect-pollinated lineages, rather than the reverse. We combined morphological and DNA data to infer the phylogeny and age of the Australian genus Hakea, using 9.2 kilobases of plastid and nuclear DNA and 46 morphological characters from a taxonomically even sampling of 55 of the 149 species. Hakea is rooted confidently in a position that has not been suggested before. The phylogeny implies that bird pollination is primitive in Hakea and that multiple shifts to insect pollination have occurred. The unexpectedly young age of Hakea (a crown age of ca. 10 Ma) makes it coincident with its primary bird pollinators (honeyeaters) throughout its history. Our study demonstrates that Hakea is an exception to the more commonly described shift from insect to bird pollination. However, we note that only one previous phylogenetic study involved Australian plants and their honeyeater pollinators and that our finding might prove to be more common on that continent.