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Genetic Diversity in Meso-American Mahogany, assessed using
RAPDs
A.C.M. Gillies, C. Navarro, A.J. Lowe, A.C. Newton, M. Hernandez, J. Wilson and J.P.
Cornelius.
Institute of Terrestrial Ecology (ITE), Centro Agronomico Tropical de Investigacion y
Ensenanza (CATIE), Institute of Ecology and Resource Management, University of Edinburgh.
© Photo courtesy of S.Cavers.
INTRODUCTION
The economically important timber tree species Mahogany, Swietenia
macrophylla, is
threatened throughout its range by selective logging and deforestation. For the future
survival of these genetic resources it is important that the remaining populations of
S.
macrophylla are carefully managed and the level and distribution of genetic diversity
understood.
METHODS
Leaf material from 420 S. macrophylla trees in 20 populations from across Central America
was sampled (see Fig. 2). DNA was extracted and analysed using 102 random amplified
polymorphic DNA (RAPD fragments, generated by 10 decamer primers.
Factors that could influence the level of genetic diversity in populations were tested
for significance using a multiple regression analysis. (i.e. ecotype, logging, proximity
to Pleistocene refugia & ecotypic characters.)
RESULTS
- Most genetic diversity is maintained within populations, which is expected for a highly
outcrossing species.
- Logging significantly decreases genetic diversity in those populations experiencing
it.
- Populations from similar ecotypic zones appear to be more closely related
genetically.
RECOMMENDATIONS
1. Logging of the remaining populations needs to be strictly controlled if genetic
resources are to be maintained, as current levels appear to be unsustainable.
2. The remaining populations of S. macrophylla need to be protected and seed and gene
banks should be established.
3. The impact of logging upon the genetic diversity of future generations of S.
macrophylla should be studied by comparing progeny arrays derived from seed pollinated in
logged and unlogged populations.
To download poster of Swietenia macrophylla results in PowerPoint format
(2678KB) click here
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