A more specific interest is the historical biogeography of the
Indo-Pacific area. This area is well suited for this kind of research
for several reasons. Firstly, it is a place where three of the earth's
plates interact, and is therefore also widely studied by geologists.
Secondly, the land masses consist mostly of islands, making the
recognition of areas of endemism relatively easy. And thirdly, it is
inhabited by a large number of monophyletic groups with many species of
restricted distribution. Moreover, its flora and fauna are actively
investigated by many taxonomists from The Netherlands and abroad for
the Flora Malesiana and Fauna Malesiana projects, coordinated by the Botany and Terrestrial Zoology departments of NBC Naturalis, respectively. Together with Dr P. Hovenkamp and Prof.Dr P.C. van Welzen, an analysis of the biogeographic history
of this region using a large database was presented at the XVI
International Botanical Congress. In 2011 we presented a similar
analysis using more modern data and techniques at the XVIII
International Botanical Congress.
In 2013, Van Welzen, Dr D. Thomas, mrs V. Ung and I presented an
analysis of the biogeography using different approaches to a more
modern molecular database at the 2013 Southeast Asian Geology and
Evolution meeting in Berlin.
In addition to the above, I am interested in the phylogeny of Anacardiaceae. At the Bolus Herbarium, University of Cape Town, I started work on a cladistic and biogeographic analysis of the genus Ozoroa Del. (Anacardiaceae), and the related monotypic genus Heeria (Thunb.) Meissn. Ozoroa contains about 40 species, and occurs on the savannas and shrublands of sub-Saharan Africa. Two subregions have particularly high numbers of endemics: SE Congo-Malawi-Zambia, and S Namibia-N South Africa. In the mountain areas of the Western Cape (South Africa) it is replaced by Heeria. This pattern of a Cape endemic with its closest relatives in tropical Africa is quite unusual, and is the main reason for doing this investigation.
The period January-April 2000 I spent at New York Botanical Garden's Lewis B. and Dorothy Cullman Program for Molecular Systematics Studies doing molecular phylogenetic research on the tribe Rhoeae, in cooperation with Drs. L. Struwe and J. Mitchell.
During 2001-2002 I was a post-doc at the Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, to construct a phylogeny of the genus Yponomeuta (Lepidoptera: Yponomeutidae) using primarily molecular data (16S, ITS, and COII). Trees were constructed using maximum parsimony, maximum likelihood and Bayesian inference methods on the different data partitions separately, and in a total-evidence approach. Thy resulting taxon trees were used to reconstruct the evolutionary events that have led to the present distribution of the genus, both geographically and in terms of the host plants used. This work, done in cooperation with Prof.Dr. Steph Menken, his PhD student Niek Lieshout, and Dr Sandrine Ulenberg, has been published in PLoS ONE.
Until recently I was honorary scientist at the Naturalis Biodiversity Center, Botany department, in Leiden. My main interest at the moment is still the biogeography of Southeast Asia, which I analyse using an expanded version of my 2013 data matrix, and a new approach I am developing to include temporal information in pattern-based analyses.
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