Title:
Genetic structure and breeding system in a social wasp and its social parasite
Genetic structure and breeding system in a social wasp and its social parasite
Author(s)
Hoffman, Eric A.
Kovacs, Jennifer L.
Goodisman, Michael
Kovacs, Jennifer L.
Goodisman, Michael
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Abstract
Background: Social insects dominate ecological communities because of their sophisticated group
behaviors. However, the intricate behaviors of social insects may be exploited by social parasites,
which manipulate insect societies for their own benefit. Interactions between social parasites and
their hosts lead to unusual coevolutionary dynamics that ultimately affect the breeding systems and
population structures of both species. This study represents one of the first attempts to understand
the population and colony genetic structure of a parasite and its host in a social wasp system.
Results: We used DNA microsatellite markers to investigate gene flow, genetic variation, and
mating behavior of the facultative social parasite Vespula squamosa and its primary host, V.
maculifrons. Our analyses of genetic variability uncovered that both species possessed similar
amounts of genetic variation and failed to show genetic structure over the sampling area. Our
analysis of mating system of V. maculifrons and V. squamosa revealed high levels of polyandry and no
evidence for inbreeding in the two species. Moreover, we found no significant differences between
estimates of worker relatedness in this study and a previous investigation conducted over two
decades ago, suggesting that the selective pressures operating on queen mate number have
remained constant. Finally, the distribution of queen mate number in both species deviated from
simple expectations suggesting that mate number may be under stabilizing selection.
Conclusion: The general biology of V. squamosa has not changed substantially from that of a
typical, nonparasitic Vespula wasp. For example, population sizes of the host and its parasite appear
to be similar, in contrast to other social parasites, which often display lower population sizes than
their hosts. In addition, parasitism has not caused the mating behavior of V. squamosa queens to
deviate from the high levels of multiple mating that typify Vespula wasps. This stands in contrast to
some socially parasitic ants, which revert to mating with few males. Overall, the general similarity
of the genetic structure of V. maculifrons and V. squamosa presumably reflects the fact that V.
squamosa is still capable of independent colony founding and thus reflects an intermediate stage in
the evolution of social parasitism.
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Date Issued
2008-08-20
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