The tropical tree family Sapotaceae is a major research focus of the Royal Botanic Garden Edinburgh. The family contains over 50 genera and about 1200 species and is both ecologically and economically important. It is the second most valuable timber tree family in Southeast Asia. The copious latex found in their wood has been used as gutta-percha and chewing-gum. Many other species produce edible fruits such as sapote and sapodilla.
The principal aim of the Sapotaceae research programme is to produce and facilitate the production of monographs and phylogenies of understudied taxa, in particular species rich and pan-tropical genera. Southeast Asian and Neotropical taxa are poorly studied and are of particular interest. International collaboration and field expeditions are providing additional material necessary for taxonomic, molecular phylogenetic and biogeographic research.
The genus Manilkara
Dr Vanessa Plana, a Peter Davis Research Fellow, is working towards a revision of the African species of the genus Manilkara. Each species will be mapped and a key to the identification of the species written. All specimen data is being databased using PADME with the view to making this available on the World Wide Web. A PhD project being undertaken by Kate Armstrong has completed the monograph of the genus by revising the Southeast Asian and Pacific island taxa. Kate has also produced a molecular phylogeny of the whole genus that was used to determine its biogeographic history.
The Tribe Isonandreae
Dr Peter Wilkie and Dr James Richardson are currently conducting detailed phylogenetic studies in the Southeast Asian centred tribe Isoandreae that includes species-rich genera such as Palaquium and Madhuca whose generic limits are unclear. This will provide the framework for monographic publications of genera in this group. We are also closely collaborating with researchers at the Natural History Museum in Stockholm and the Royal Botanic Gardens Kew to determine the phylogenetic position of this tribe within Sapotaceae and towards producing a revised classification of the family as a whole.
The Subfamily Chrysophylloideae
Generic limits in this subfamily are particularly poorly circumscribed. Swenson, Richardson and Bartish (2008) demonstrated that many morphological characters are homoplasious and indicated that genera will need to be redefined. Additional samples are being added to a molecular phylogeny that will be used to improve generic delimitation. Dr Barbara Mackinder is working on African representatives of the subfamily, and we are working with the Natural History Museum in Stockholm who are working on Australasian taxa and various Neotropical research groups, with a particular emphasis on the Colombian species, are contributing taxa from this region. A study of the biogeographic history of the subfamily was published in Journal of Biogeography in 2010.
Sapotaceae Resource Centre
A key aspect of our programme is the development of the Sapotaceae Resource Centre website. This incorporates a searchable specimen database with information collated from a range of national and international collaborators. The site provides access to information on specimen records and field and herbarium specimen images (including types). It also provides links to other Sapotaceae researchers, studies and publications. Future plans include the development of online interactive keys.
Sapotaceae are found throughout the tropics but the evolutionary processes that led to this distribution pattern are unclear. Genera such as Manilkara that are well represented throughout the tropics are ideal candidates for testing hypotheses of diversification on different continents. Isonandreae are of particular interest in elucidating biogeographic patterns within Southeast Asia and studies on Colombian Chrysophylloideae will determine how geological events have shaped distribution patterns in Northwestern South America and Central America. Details on the experimental approaches for phylogenetics and biogeography projects are described in the Environmental Change and Biogeography project description.
Our research group is contributing accounts to regional floras. Currently Dr Peter Wilkie is producing a family account for the Flora of Peninsular Malaysia.
Clayton, J. 2003 Pantropical genera: systematics and biogeography. A pilot study using Manilkara. MSc thesis. Univ. Edinburgh) was supervised by Dr Toby Pennington.
Swenson, U., RICHARDSON, J.E. and Bartish, I.V. 2008. Multi-gene phylogeny of the pantropical subfamily Chrysophylloideae (Sapotaceae): Evidence of generic polyphyly and extensive morphological homoplasy. Cladistics 24: 1-26.
Plana, V. 2008. Taxonomic revision of the genus Manilkara (Sapotaceae) in Madagascar. Edinburgh Journal of Botany 65(3): 1-14.
Bartish, I.V., RICHARDSON, J.E., Antonelli, A. & Swenson, U. 2010. Vicariance or long-distance dispersal: historical biogeography of the pantropical subfamily Chrysophylloideae (Sapotaceae). Journal of Biogeography 38: 177-190.
For further information, please contact the Sapotaceae Research Group members: