Am. Escalante et al., GENETIC-STRUCTURE AND MATING SYSTEMS IN WILD AND CULTIVATED POPULATIONS OF PHASEOLUS-COCCINEUS AND PHASEOLUS-VULGARIS (FABACEAE), American journal of botany, 81(9), 1994, pp. 1096-1103
We present a study of the genetic variation, genetic structure, and ou
tcrossing rate of two wild populations of Phaseolus coccineus ssp. for
mosus (both from Central Mexico), two cultivated populations of P. coc
cineus ssp. coccineus (one from Central Mexico, the other from Chiapas
), and one cultivated population of P. vulgaris (from Central Mexico),
using seven electrophorectic loci. All the populations of P. coccineu
s showed high and similar levels of genetic variation, without differe
nces among wild and cultivated populations (H ranged between 0.187 to
0.271). In contrast, P. vulgaris has low levels of genetic variation (
H = 0.041). The three P. coccineus populations from Central Mexico wer
e genetically similar, while the cultivated P. coccineus from Chiapas
and the cultivated P. vulgaris from Central Mexico were very different
. In all the loci and all the populations for both species, the fixati
on indices (F) were positive and differed significantly from random ma
ting expectation in 59% of the cases for P. coccineus. The highest F w
as the estimated for P. vulgaris. For P. coccineus, the multilocus out
crossing rate estimates ranged from 0.592 to 0.698, and these did not
differ significantly among populations. For P. coccineus, we also esti
mated the outcrossing rate for each of 60 different families, showing
great variation, with a majority of families with a t between 0.8 and
1, but a substantial fraction of the families with a t as low as 0.12-
0.20. The domestication process has neither eroded the levels of genet
ic variation of the cultivated populations of P. coccineus nor changed
its mating system.