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Gene Flow and Genetic Structure in the Wild–Weedy–Domesticated Complex of Phaseolus lunatus L. in its Mesoamerican Center of Domestication and Diversity
Author(s) -
Martínez-Castillo Jaime,
Zizumbo-Villarreal Daniel,
Gepts Paul,
Colunga-GarcíaMarín Patricia
Publication year - 2007
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci2006.04.0241
Subject(s) - domestication , gene flow , biology , genetic diversity , phaseolus , introgression , gene pool , allele , genetics , evolutionary biology , botany , gene , genetic variation , population , sociology , demography
ABSTRACT The role of gene flow in autogamous domesticated species diversity and their wild relatives is an issue that requires more field data. Using nine microsatellite loci, an analysis was done of the magnitude and direction of gene flow in the wild–weedy–domesticated complex of Phaseolus lunatus L. under traditional agricultural conditions in four regions on the Yucatan Peninsula, Mexico, its center of domestication and diversity in Mesoamerica. Two complementary methods were used. The Bayesian genotype assignment approach showed that recent gene flow was low at both the intraregional and interregional levels. The same was found with the frequency method for long‐term gene flow ( Nm intraregional from 0.31 to 0.51, and Nm interregional = 0.44). In addition, the gene flow from domesticate to wild populations was three times higher than in the opposite direction. This asymmetry can be explained by regional agricultural practices and seed selection criteria. Domesticate alleles were shown to be entering wild populations of different agricultural regions, suggesting exchange of domesticated seed between farmers of different regions. These results are very important because they show that P. lunatus on the Yucatan Peninsula has a predominantly domesticate to wild gene flow. This situation may lead to genetic assimilation of wild lima bean by its domesticated counterpart and may lead to the possible escape of transgenes in this center of origin and diversity.