Biology Reference
In-Depth Information
less pollen (Figure 2.12). h is relationship is heritable and varies con-
siderably within and between populations.
7.5 Evidence for the Reproductive-Ground-Plan Hypothesis
Evidence for the reproductive-ground-plan hypothesis was building,
but we had many skeptics. Criticism came in basically four l avors: (1)
We really cannot understand the evolutionary history of social behav-
ior by studying honey bees because they are socially too advanced, and
the evolutionary history has probably been erased by 50 million years
of social evolution. We dismissed this criticism as too pessimistic and
continued to look for the signature of natural selection on the reproduc-
tive regulatory networks. h at was the purpose of this research enter-
prise. (2) We know nothing about how reproductive state and behavior
are coupled in closer relatives of bees. We considered this a valid criti-
cism and an important question, but certainly not fatal to our hypothesis
because the relationship between ovary state and behavior is widespread
in animals. (3) Support for our hypothesis was derived from artii cially
selected strains and probably does not rel ect what goes on in “normal”
bees. h is was just wrong because we had substantiated our results with
highs and lows along with wild-type bees. (4) Critics just don't believe
that there is a relationship between vitellogenin and foraging behav-
ior . . . just because they don't believe it. h is was dii cult to dismiss
because it was outside the context of the scientii c method and was based
on belief rather than evidence.
7.5.1 Ovaries, Vitellogenin, and Behavior
We made the argument that the amount of vitellogenin circulating in
the blood of young worker honey bees af ects their foraging behavior
later in life. Workers are stripped of most of their Vg when they become
foragers, so Vg titers are not likely to be directly af ecting foraging deci-
sions. We also argued that the amount of circulating Vg is af ected by
the size of the ovary. One mechanism for this could be the positive cor-
relation between ovary size and ecdysteroid levels. Ecdysteroids are
