Geographical allozymes differentiation in wild Phaseolus lunatus L. of the Central Valley of Costa Rica and its implications for conservation and management of populations

• Published in: Biotechnologie, agronomie, société et environnement Vol. 11; no. 4; pp. 287 - 297
• Main Authors: Bi, AIZ, Baudoin, J-P
• Format: Journal Article
• Language: English
• Published: Université de Liège 01-01-2007; Presses Agronomiques de Gembloux
• Subjects: autocorrelation; autocorrélation; conservation in; haricot de Lima; in situ conservation; Lima; Lima bean; Phaseolus lunatus; spatial genetic structure; structure génétique spatiale; Argentina, Buenos Aire, Lima; Costa Rica
• ISSN: 1370-6233; 1780-4507

To suggest a conservation and management strategy for wild Lima bean (Phaseolus lunatus L.) in the Central Valley of Costa Rica, we examined the spatial distribution of genetic variation in 96 populations, using ten enzyme loci to analyse F-statistics and Moran's I. These loci displayed 20 alleles, of which 5 with relatively high frequencies were exclusively localised in the central part of the Valley. The estimates of F-statistics indicated a high level of genetic differentiation between populations (Mean F sub(ST)=0.504 plus or minus 0.094). Such a value suggested that wild P. lunatus maintains about 50% of its genetic variation among populations. Moreover, the levels of inbreeding (F sub(IT)=O.882 plus or minus 0.026 and F sub(IS)=0.761 plus or minus 0.012) were high and significantly different from zero. Hence the genotypic composition of wild Lima bean deviated from Hardy-Weinberg proportions as a result of genetic differentiation between populations and non-random mating within populations. Spatial autocorrelation analysis using four loci showed positive and significant Moran's I at short distance in most cases. The resulting correlograms displayed up and down stochastic variations and indicated a patchy genetic structure. Combining the results obtained with those previously published on genetic structure, mating system, gene flow, and demography, we suggested probable causal factors and evolutionary mechanisms driving the genetic variability of the populations analysed. In addition, we indicated populations that should be preserved and proposed a reliable in situ management strategy.