To examine whether ecological traits associated with the New Zealand flora might influence species richness, I used published molecular phylogenies to compare traits associated with species richness of monophyletic groups in New Zealand and the relative species richness of New Zealand and their sister lineages. Species richness in New Zealand lineages tended to be lower than but not significantly different from their sister lineages. New Zealand lineages with fleshy fruits have lower numbers of species than their sister lineages, suggesting that regional differences in community processes can influence speciation or extinction. Lineages with sister taxa found exclusively on islands are characterized by low species richness both in New Zealand and elsewhere. In addition, species number was higher in insect-pollinated New Zealand lineages than in wind- or bird-pollinated lineages. There was no association with other correlates of mating system, including plant woodiness, gender dimorphism, and floral display. These results suggest that long-distance dispersal, dependence on abiotic disperser or pollinator, and time since diversification all contribute to the species richness of a lineage.
