Population Genetic Structure and Mating System of Swietenia macrophylla King (Meliaceae) in the Brazilian Amazon: Implications for Conservation by

Mahogany, Swietenia macrophylla (Meliaceae) is the most valuable hardwood species in Neotropics and is seriously threatened owing to over-exploitation and habitat destruction. The population genetic structure and mating system of S. macrophylla were studied in the Brazilian Amazon for conservation purposes. Ten highly polymorphic micro satellite markers were developed from an enriched genomic library of S. macrophylla and combined in three multiplexed fluorescencebased genotyping systems. The number of alleles per locus ranged from 11 to 25 (mean = 15.8). The probability of genetic identity (7x1015) and the probability of paternity exclusion (0.999998) found over all loci indicate the high discriminating power of these markers. The genetic structure was investigated in seven populations 82,103 km apart. High genetic diversity was detected within populations (mean He = 0.761, range 0.719-0.800) and a significant level of inbreeding was found (f = 0.046, P<0.0001, range 0.014-0.097) indicating nonrandom mating of individuals within populations. Genetic differentiation among populations was significant (A = 0.12 and p = 0.14, P<0.0001), but no clear pattern of isolation by distance was found. Conservation strategies for mahogany should take into account the existence of important genetic structuring of populations. S. macrophylla seems to have adaptations that preferentially produce outcrossed progeny but also allows for selfing. The high