Molecular Population Genetics of Four Closely Related Alcantarea Species (Bromeliaceae) Adapted to 'Inselbergs' in the Atlantic Rainforest of Brazil - COMPLETED 2008
The inselbergs of the Brazilian Atlantic Rain Forest form terrestrial “islands” that are isolated from the surrounding forest by steep gradients in humidity, temperature and irradiation, and by drastic changes in soil substrates. Bromeliads (Bromeliaceae) are particularly well represented among plants adapted to the extreme growing conditions on inselbergs.
Thelma Barbarà Santos, as a full-time PhD student at Open University/RBG Kew, started this project in 2003 to study the molecular population genetics of four members of the Alcantarea species complex endemic to inselbergs of coastal Atlantic Brazil, which includes Alcantarea imperialis, A. geniculata, A. glaziouana and A. regina. The PhD project was supervised by Dr Mike Fay (Director of studies), Dr Simon Mayo, Dr Christian Lexer, and Dr Colin Clubbe at Kew, and Dr Gustavo Martinelli at Jardim Botanico do Rio de Janeiro. Its aim was to study genetic variability at nuclear DNA microsatellites and, if sufficient polymorphism was found, at plastid DNA markers. Fundamental questions regarding the breeding system, metapopulation dynamics, and distribution of genetic diversity across a highly fragmented landscape were also to be addressed.
This project asked specific questions: (1) What is the relative importance of sexual recombination versus asexual (clonal) reproduction in generating the patterns of genetic variability observed within each species? (2) Is gene flow between inselberg populations sufficient to maintain Alcantarea species as cohesive units? (3) How different, or how similar, are local genetic structures on different inselbergs? (4) How well do patterns of genetic diversity correlate among co-occurring Alcantarea species, and is there any genetic evidence for interspecific gene flow in the past? (5) What are the differences between patterns of variability observed at nuclear and plastid DNA markers, and are these differences useful for inferring the relative importance of pollen vs. seed dispersal? The PhD was awarded in 2008 and results of the work have been presented at the International Botanical Congress (IBC) in Vienna, 2005, and at the Population Genetics Group (PopGroup) meeting in Edinburgh, UK, 2005, and have also resulted in a number of peer-reviewed journal publications.
Project Partners and Collaborators
Jardim Botânico do Rio de Janeiro
Kew Overseas Fieldwork Committee
KLARF (Kew Latin American Research Fellowships program)