The role of Gp-9 in regulating social behavior in fire ants
Gotzek, Dietrich Axel
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This research presented here represents a modest contribution to the regulation of social organization in the red imported fire ant, Solenopsis invicta Buren, and close relatives. Colony queen number is associated with a certain allele at the nuclear proteincoding locus general protein-9 (Gp-9). Multiple queen colonies (polygyny) always contain the b allele. Single queen colonies (monogyny) always and only contain the B allele. The research presented here seeks to begin to bridge the gap between molecular pattern and process in our understanding of the association between Gp-9 and polygyny in fire ants. I have sought to show how a relatively small number of the b allele carrying workers are sufficient to elicit polygyne behavior and that queen effects do not influence the acceptance of supernumerary queens. This represents an important first step into understanding the ties between individual genotypes and colony level expression of social organization. I have also attempted to show that single nucleotide substitutions at the Gp-9 locus are not sufficiently associated with polygyne behavior, but that several such changes must occur for the expression of the polygyne phenotype. This raises interesting questions about the validity of the presumed causal role of the b-like alleles at Gp-9 in inducing polygyne behavior in South American fire ants. Finally, I discuss the state of our current understanding of Gp-9 and its role in regulating social behavior, resulting in a simple, testable model, and suggestions for future avenues of research. Whether Gp-9 remains the prime candidate gene for controlling social organization in fire ants remains to be seen. But even if it does not, it will deserve continued attention by students of social behavior.