PHENOTYPIC VARIATION AMONG AND WITHIN WILD POPULATIONS OF PEPPER FROM NORTHWESTERN MÉXICO

Abstract

The hierarchical distribution of phenotypic variation among populations, among and within families, and the proportion of such variation genetically based was estimated in four populations of wild pepper (Capsicum annuum var. glabriusculum) from northwestern México. The traits measured were: plant height, stem diameter, leaf length, leaf width, number of fruits per plant, number of seeds per plant, number of seeds per fruit and seed weight. Out of the total variation, 61.8 % was found within families, 24.7 % among families and 13.5 % among populations. From the total phenotypic variation, 38.2 % was genetically based, from which 30.1 % was among and 69.9 % within (in families) populations. The broad sense heritability varied among traits and populations. Plant height, stem diameter, leaf length, number of fruits per plant, number of seeds per plant and individual seed weight showed minimum heritability values. In leaf width and number of seeds per fruit, the heritability values varied from 0.10 to 0.75. In three populations the minimum values of heritability were of zero or close to zero for three different traits in each population, while in the remaining populations the heritability values varied from 0.23 to 0.75. The two adjacent populations (Yecorato Mezquite and Yecorato Camino) separated by only 500 m differed substantially in the heritability of five out of eight traits analyzed. These results suggest that the potential for evolutionary change in a particular trait varies widely among the studied populations, even in those populations separated by a small distance. Within family variation was high and uniformly distributed across populations in all traits, except in stem diameter. This high variation can be caused by differences in plasticity of individuals within families.