Biology Reference
In-Depth Information
sected, and marker inheritance was determined for markers located
near the pollen-hoarding QTL previously found. Graham found that
pln1, pln2,
and
pln3
explained signii cant amounts of the variation in
the number of ovarioles in the mapping-population backcross, thus
coni rming the ef ects of these QTLs on ovary size in a cross completely
independent of the high- and low-strain bees.
In an additional QTL mapping study, Kate Ihle, a graduate student
co-advised by Gro Amdam and me, investigated simultaneously the
ovary size of workers (number of ovarioles) and the amount of juvenile
hormone circulating in their hemolymph in response to vitellogenin
knockdown (see Chapter 7). Juvenile hormone (JH) and vitellogenin
(Vg) coregulate each other. Decreasing Vg results in an increase in JH,
and vice versa. h is has been shown to be true in general in honey bees;
however, they do not coregulate each other in the low strain. Ihle
mapped ovary size and JH response to Vg in a high-strain backcross
worker population and found that
pln3
af ected the regulation of JH by
Vg (u npu bl i s he d).
h e architecture suggests a causal structure of selection on stored
pollen, resulting in the substitution of alleles of genes that af ect the size
and development of ovaries that af ect hormones that are part of the re-
productive regulatory network that, in turn, af ect sensory responses
and behavior (Figure 6.5). But what are the genes represented by the
QTLs we mapped?
6.7 Candidate QTLs
h ree events in the very long history of honey bee research have
greatly enabled the success of the honey bee as a genetics research
organism. h e i rst was the development of the removable-frame hive
by Lorenzo Langstroth. h is allowed beekeepers and researchers to
remove, examine, replace, and exchange combs of honey, pollen, and
brood. h e second was the development of instrumental insemina-
tion, mostly attributed to my mentor and good friend for more than
25 years, Harry Laidlaw, and to Otto Mackensen, a geneticist for the
U.S. Department of Agriculture. Instrumental insemination enabled
researchers to control the matings of queens and do real genetic re-
