CRAYN, DARREN M.*, J. ANDREW C. SMITH, KLAUS WINTER, AND RANDALL G. TERRY. Smithsonian Tropical Research Institute, Ancon, Republica de Panama, Department of Plant Sciences, University of Oxford, Oxford, United Kingdom, Division of Biological Sciences, University of Montana, MA. - The evolution of crassulacean acid metabolism in Bromeliaceae: a molecular systematic approach.
Bromeliaceae form one of the most distinctive elements of the
neotropical forest flora. Extensive investigations in recent years
have resulted in a much-improved understanding of the ecophysiology of
the Bromeliaceae, particularly as regards the occurrence and
expression of the water-conserving photosynthetic pathway known as
crassulacean acid metabolism (CAM). Together with Orchidaceae,
Bromeliaceae form the bulk of the neotropical forest CAM flora, but
Bromeliaceae display a considerably greater diversity of growth forms.
Thus Bromeliaceae are an ideal group for the study of the evolution
of CAM and the epiphytic habit. However, interpretations of possible
evolutionary transitions are confounded by the lack of a robust
phylogeny for bromeliads. Previous molecular work has suffered from
insufficient variation in the data precluding the convincing
resolution of many relationships. We initiated a study to address
this problem using sequence data from one nuclear (ITS 1 and 2) and
three chloroplast (the atpB-rbcL spacer, matK and
the rps16 intron) regions. Data gathered to date and the
impact of these on the interpretation of evolutionary transitions in
the family will be discussed.
Key words: atpB-rbcL cer, Bromeliaceae, crassulacean acid metabolism, ITS, matK, rps16 intron