Genetics, Vol 145, 961-974, Copyright © 1997


INVESTIGATIONS

Multilocus Evolution in Fire Ants: Effects of Selection, Gene Flow and Recombination

K. G. Ross
Department of Entomology, University of Georgia, Athens, Georgia 30602-2603

The reproductive success of individual fire ant queens (Solenopsis invicta) previously has been shown to be strongly influenced by their genotype at a single enzyme-encoding gene, designated Pgm-3. This paper presents evidence that a second, tightly linked gene, designated Gp-9, is under similarly strong selection in these ants. Selection appears to act independently on the two genes and is detectable in only one of the two social forms of this species (the ``polygyne'' social form, in which nests contain multiple fertile queens). Strong directional selection on Pgm-3 in this form involves worker destruction of all queens with genotype Pgm-3(AA) before they reproduce. Selection on Gp-9 is more complex, involving both lethality of all Gp-9(bb) females and a strong or even complete survival advantage to reproductive queens with the heterozygous genotype Gp-9(Bb). Pgm-3 and Gp-9 are tightly linked (r(f) = 0.0016) and exhibit strong gametic phase disequilibrium in introduced populations in the U.S. This disequilibrium seems not to have stemmed from the founder event associated with the introduction, because the same associations of alleles found in the U.S. apparently occur also in two native populations in Argentina. Rather, selection acting independently on Pgm-3 and Gp-9, in conjunction with gene flow from the alternate, ``monogyne'' social form (in which nests contain a single fertile queen), may explain the origin of disequilibrium between the two loci in polygyne fire ants.


This article has been cited by other articles:


Home page
GeneticsHome page
G. N. Fritz, R. K. Vander Meer, and C. A. Preston
Selective Male Mortality in the Red Imported Fire Ant, Solenopsis invicta
Genetics, May 1, 2006; 173(1): 207 - 213.
[Abstract] [Full Text] [PDF]


Home page
Mol Biol EvolHome page
M. J. B. Krieger and K. G. Ross
Molecular Evolutionary Analyses of the Odorant-Binding Protein Gene Gp-9 in Fire Ants and Other Solenopsis Species
Mol. Biol. Evol., October 1, 2005; 22(10): 2090 - 2103.
[Abstract] [Full Text] [PDF]


Home page
GeneticsHome page
K. G. Ross, M. J. B. Krieger, and D. D. Shoemaker
Alternative Genetic Foundations for a Key Social Polymorphism in Fire Ants
Genetics, December 1, 2003; 165(4): 1853 - 1867.
[Abstract] [Full Text] [PDF]


Home page
Behav EcolHome page
M. A. D. Goodisman and K. G. Ross
Queen recruitment in a multiple-queen population of the fire ant Solenopsis invicta
Behav. Ecol., July 1, 1999; 10(4): 428 - 435.
[Abstract] [Full Text] [PDF]


Home page
Proc. Natl. Acad. Sci. USAHome page
K. G. Ross and L. Keller
Genetic control of social organization in an ant
PNAS, November 24, 1998; 95(24): 14232 - 14237.
[Abstract] [Full Text] [PDF]


Home page
Proc. Natl. Acad. Sci. USAHome page
G. J. Velicer, L. Kroos, and R. E. Lenski
Loss of social behaviors by Myxococcus xanthus during evolution in an unstructured habitat
PNAS, October 13, 1998; 95(21): 12376 - 12380.
[Abstract] [Full Text] [PDF]


Home page
ScienceHome page
M. J. B. Krieger and K. G. Ross
Identification of a Major Gene Regulating Complex Social Behavior
Science, January 11, 2002; 295(5553): 328 - 332.
[Abstract] [Full Text] [PDF]