Biology Reference
In-Depth Information
Colonies composed of workers that were hybrids of the high and low
strains performed like low-strain colonies for pollen hoarding, demon-
strating directional dominance for the low-pollen-hoarding trait. How-
ever, they stored signii cantly more honey than either strain.
5.3 Individual Behavior
In the following sections, I will detail many of the experiments and re-
sults that have resulted in a growing understanding of the phenotypic
architecture of foraging behavior. h e ef ects of selection on pollen-
hoarding behavior were as we expected on the basis of the study of Rick
Hellmich and Walter Rothenbuhler. To study individual behavior of
workers, we conducted common-garden experiments (Figure 4.5). Bees
were collected as foragers. We tried to collect bees during their i rst
day of foraging when we studied foraging-initiation age (age of i rst
foraging). However, for studies of foraging behavior, we usually let a
group of foragers build up for each of the genetic groups we wanted to
compare. We then collected large samples of foragers over a few con-
tiguous days. Collecting bees when they initiate foraging is less reli-
able for resource-foraging behavior studies because collections are of-
ten made over several weeks during which the weather and available
l owers have large ef ects on the loads collected (that is, there is more
environmental variance). Bees that initiate foraging later in life expe-
rience dif erent foraging environments than those that initiate forag-
ing earlier.
5.3.1 Age of Initiation of Foraging and Life Span
High-strain bees initiate foraging up to 12 days earlier in life. h is re-
sult was unexpected but consistent with the results of the selection by
Hellmich and Rothenbuhler. h e life span of a bee can be divided into
two parts: preforaging and foraging. h e onset of foraging marks a major
transition for bees with major consequences for mortality. Bees that initi-
ate foraging later in life live longer, overall, but have shorter foraging
spans. Every day of life before the initiation of foraging “costs” one-third
