Genetics of wild and managed populations of Leucaena esculenta subsp. esculenta (Fabaceae; Mimosoideae) in La Montana of Guerrero, Mexico
2005
Zarate, S. | Perez-Nasser, N. | Casas, A.
Genetic consequences of silvicultural management of Leucaena esculenta subsp. esculenta were analyzed from eight allozyme loci in half-sib families of one wild and one managed in situ (selectively cleared) population from La Montana de Guerrero region, Central Mexico. A reference sample (including wild, feral and cultivated individual plants) from the states of Morelos, Puebla and Guerrero, Mexico was also analyzed. Genetic variation, population structure and mating system were analyzed. All loci showed high variation (75-87.5% polymorphic loci at 95% level; 2.4-2.8 mean number of alleles per locus). All progenies showed heterozygous deficiency, but both wild and managed parental inbreeding coefficients were negative, suggesting heterosis. Progenies of managed populations differed from those of the wild and reference samples (Nei's unbiased identities 0.874-0.934). Biparental inbreeding is suggested by Wright's-statistics (f = 0.313), and by outcrossing rate estimates: t(m) = 0.644 (SE 0.094), and 0.645 (SE 0.193); t(s) = 0.576 (SE 0.189), and 0.523 (SE 0.182), for managed and wild samples respectively. Population differentiation is significant (theta = 0.210). The species is self-incompatible and deviations from the mixed mating model were found. Indirect estimates of products of effective population size (N(e)) by the proportion of migrants (N(m)) were moderate, as were the N(e) values. Variation due to ecotypic differentiation (related to altitude), prolonged artificial selection, and introduction from other areas is supported. A model of domestication of seed-propagated trees is suggested, based on extensive and in situ selection of locally adapted populations, and their diffusion to other areas.
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