Multiplexed systems of microsatellite markers for genetic analysis of mahogany, Swietenia macrophylla King (Meliaceae), a threatened neotropical timber species.

Mahogany (Swietenia macrophylla King [Meliaceae]) is the most valuable hardwood species in the neotropics. Its conservation status has been the subject of increasing concern due to overexploitation and habitat destruction. In this work we report the development and characterization of 10 highly variable microsatellite loci for S. macrophylla. Twenty-nine percent of the 126 sequenced mahogany clones yielded useful microsatellite loci. Three high-throughput genotyping systems were developed based on polymerase chain reaction (PCR) multiplexing of these mahogany loci. We identified a total of 158 alleles in 121 adult individuals of S. macrophylla, with an average of 15.8 alleles (range 11-25) per locus. All loci showed Mendelian inheritance in open-pollinated half-sib families. The mean expected heterozygosity was 0.84 and the mean observed heterozygosity was 0.73. The combined probability of identity-the probability that two individuals selected at random from a population would have identical genotypes--was 7.0 x 10(-15), and combined probability of paternity exclusion was 0.999998 overall loci. These microsatellite loci permit precise estimates of parameters such as gene flow, mating system, and paternity, thus providing important insights into the population genetics and conservation of S. macrophylla.