Biology Reference
In-Depth Information
But how does social behavior evolve to be more complex? In Chapter 5,
I dig deeper into the complex social behavior of food foraging and stor-
ing and show how we successfully changed the social organization of
two populations of bees by artii cial selection. How does selection af-
fect the social system? Selection must change the dynamic systems pa-
ram e ters of N, K, and {F}.
Selection on N could increase the total number of individuals in a
colony or the numbers that are competent to perform a task. For exam-
ple, queen fecundity could increase. For a given, i xed life span of work-
ers, a higher egg-laying rate by the queen would lead to a larger number
of workers in the colony. Or the life span of workers could be extended.
h en for a given egg-laying rate of the queen, a colony would have more
workers when it reached the equilibrium point of births equal to deaths.
Selection on K af ects the connectedness of individuals either di-
rectly or indirectly through their ef ects on other stimuli. Selection on K
could af ect the sensitivity of sensory sensilla (special anatomical struc-
tures that perceive stimuli) to specii c stimuli or af ect the motor pat-
terns of workers or their location in the nest, making more bees likely
to come into contact with specii c task-releasing stimuli.
Selection on {F} af ects the distribution of response thresholds of work-
ers in colonies. h is could include the average thresholds of individuals
in a colony or the variance in thresholds. h e distribution of thresholds
af ects the dynamics of model network colonies, even when the average
thresholds remain the same. Honey bee colonies with more genetic di-
versity are thermally more stable than those of lower diversity. Selection
favoring a general increase in genetic variation, for example, through
multiple mating of queens (polyandry), increases the variance in response
thresholds when there is heritable genetic variation. Also, stimulus-
response thresholds can be grouped and change with age or experience,
perhaps resulting in task sets for individuals that can change with time.
Network models where elements make decisions to be on or of to two
tasks at a time show more dynamic stability than single-stimulus-threshold
models.
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