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thousands of individuals? h is is truly a mind-boggling, complex prob-
lem. h ere is no central control of the activities of individual workers:
they have limited global information about the state of the nest and the
activities of others and behave by responding to local stimuli. From
these dif erent or gan i za tion al levels emerges self- organized collective
behavior. To better understand the mechanisms operating at the dif er-
ent organizational levels, I use a model social phenotype—the amount
of surplus pollen stored by bees.
My approach to this question has been to combine selective breeding
with mechanistic studies of behavior and physiology. I view selective
breeding as analogous to natural selection, except that with selective
breeding I, rather than the environment, am the agent of selection.
Darwin used the analogy of selective breeding repeatedly in On the
Origin of Species when he drew on the results of breeders of domestic
pigeons to show how selection can result in dramatic changes in phe-
notypes. h e same processes take place with natural selection and arti-
i cial selection at the level of changes in the frequencies of heritable
phenotypes from generation to generation. Allelic variants of genes af-
fecting the traits I select increase or decrease in frequency in my breed-
ing populations just as they do in natural populations. Response to my
selection is attributed to genes that are variable and af ect my traits of
interest, and genes that have the biggest ef ects on the phenotype in-
crease or decrease in frequency more rapidly than genes with smaller
ef ects. h e underlying changes in anatomy, physiology, and biochem-
istry are linked to the changes in gene frequencies, again, just as in
natural populations. h e dif erences between natural selection on nat-
ural populations and my artii cial selection on closed populations are
the size of the breeding population and the strength of the selection.
My populations are small, and I apply strong selection, while natural
populations are much larger, and selection for given phenotypic traits
is not expected to be as severe. As a consequence, with my selection
program phenotypic change is faster, genetic variation is exhausted
faster, and phenotypic changes are dominated by genes with large ef-
fects. Nonetheless, my program provides a tool to study the ef ects of
selection across levels of biological organization.
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