I officially retired from my job at The University of Melbourne in 2019, but I continue to write about ecology and to run international workshops to debate ecological issues. I am still with the University, as an Emeritus Professor and I go to the University occasionally.
I love plants! It does not embarrass me to say so. Plants are amazingly complex and highly diverse organisms on which life on earth depends. They display fascinating behaviour themselves – though the timescale for this may be quite long – while they depend upon (and in turn are depended upon by) a variety of other organisms. They are especially obliging to scientists because they (mostly) stay in the same place, they do not bite or sting and they do not require complex ethical procedures for their study! Depending on the research question, I used combinations of field and laboratory experiments, surveys and computer modelling to predict population change under different conditions and hence what action we might take to manage populations. My research often took me into natural ecosystems or into farmer’s fields, working with the people who manage the species, communities and ecosystems, and with people from various other disciplines, such as zoologists, geomorphologists and social scientists.
As a plant population biologist, I am interested specifically in the interacting processes that together determine the abundance and distribution of plant species. Thus, I studied rare species urgently requiring conservation, invasive species requiring eradication or containment, and abundant weeds that require control. My focus at the end of my career was on invasive plants and especially those invading our coastal fringe. Invasive species can have a wide variety of impacts on native plant and animal communities, geomorphology, ecosystem function, agricultural production, human health and our aesthetic appreciation of landscapes. They can also help us to understand basic population processes that apply to all organisms, such as competition, adaptation and dispersal.
The terrestrial coastal fringe is narrow but is of great ecological significance, being a habitat for plant and animal species found nowhere else and providing nesting sites for vast numbers of sea birds. It is highly disturbed, by waves, wind and human activity and organisms there must cope with extremes of salinity, aridity, temperature and nutrients. Several of my students and postdocs studied a system involving two exotic Sea-rockets (Cakile sp.), their breeding systems and their pollinators. These species, related to cabbages, are in many respects a plant analogue of the Neanderthal-Homo sapiens story – at least, that is how I see it. An earlier invader from eastern North America, an in-breeder (C. edentula), is now being displaced by a later arriving self-incompatible congener from Europe (C. maritima). Why? We have shown that they differ in phenology, lifetime reproductive output and can hybridise (with either species being the pollen donor). Their dynamics depends on introduced and native insects, which favour C. maritima, as well as diseases. Whether or not their breeding systems or their hybridisation favours local adaptation in C. maritima remains to be investigated. We also sequenced their chloroplast genomes in order to determine where in their home ranges they came from.
I collaborated with a number of people whose knowledge, skills and intellect allowed me to explore topics that I was incapable of researching alone. I thank these people for their tolerance, as well as the excitement that they injected into the lives of me and my students. My most recent collaborators included Kay Hodgins (Monash University), Loren Rieseberg (University of British Columbia), Bruce Webber (CSIRO, Perth), Mohsen Mesgaran (UC-Davis), Mark Lewis (University of Alberta), Kathleen Donohue (Duke University) and Barry Hughes (University of Melbourne).