Proteaceae - Where are we?

Abstract

Developments in understanding of the Proteaceae since 1963 are briefly reviewed and discussed in relation to morphological interpretation, DNA studies, phytogeography and phylogeny. Some of the outstanding questions are highlighted.

Starting Point

More than 30 years ago, Barbara Briggs and I (Johnson and Briggs 1963) published a hypothesis of the phylogeny of Proteaceae, a family of great interest for which no reasonably acceptable evolutionary history had been proposed. Unfortunately, at the time we wrote this paper, we were misled by conservative geologists who had not got around to accepting continental drift, and our phytogeographic understanding was much distorted by this.

Twelve years later (Johnson and Briggs 1975) we refined our complex hypotheses of phylogeny and phytogeography, in a symposium celebrating the great botanist Robert Brown. At this time we had more information on morphology and also on karyology. The latter subject, dealing with chromosome size and number, is almost completely out of favour now; nevertheless, it embraces complex character-states that need to be taken into account and assessed as to synapomorphy.

In 1975, our approach was more explicitly one of phylogenetic analysis, although we were not in a position to carry this out rigorously throughout, and it was not computerised. We also accepted certain groupings of taxa that we in fact felt might be paraphyletic with respect to others. We certainly did not wish to include any polyphyletic groups, although it now appears that some of our tribes and subtribes will need amendment to render them pure in this respect.

The 1975 classification is of course definitely not now upheld by us in all respects. Forinstance, we consider Bellendena to be most appropriately treated as constituting a subfamily distinct from Persoonioideae and indeed we encouraged the publication of Bellendenoideae (Weston 1995). We are pleased to see that our 1975 classification and suggested phylogeny are still serving as a take-off point for current re-assessment and that a good deal of it stands up, but we do not take the formal view that it is in itself a hypothesis to be tested, in the Popperian sense. There is little point in indicating that parts of it are incorrect when in fact we have modified our own thinking considerably in the light of findings over the past two decades. Rather, concentration should be on honing and modifying such very complex hypotheses, not so much in the spirit of disproving or corroborating as in seeking closer approximations to the actual phylogeny and its representation, as far as possible, in a classification.

I shall discuss briefly the areas in which progress has been or needs to be made.