Quantitative trait loci (QTLs) responsible for variation in sternopleural
bristle number in crosses
between the laboratory lines of Drosophila melanogaster OregonR
and CantonS were mapped using
information from allele frequency changes of two families of retrotransposon
markers in
divergently selected populations. QTL effects and positions were inferred
by likelihood, using
transition matrix iteration and Monte Carlo interval mapping. Individuals
from the selected
populations were genotyped for markers spaced at an average distance 4.4
cM. Four QTLs of
moderate effect ranging from 0·6 to 1·32 bristles accounted
for most of the selection response. A
permutation test of the correspondence between the mapped QTLs and the
positions of bristle
number candidate genes suggested that alleles at these candidate genes
were no more strongly
associated with selected changes in marker allele frequency than were randomly
chosen positions in
the genome.