A Y-like social chromosome causes alternative colony organization in fire ants

  title={A Y-like social chromosome causes alternative colony organization in fire ants},
  author={John Wang and Yannick Wurm and Mingkwan Nipitwattanaphon and Oksana Riba-Grognuz and Yu-Ching Huang and DeWayne Shoemaker and Laurent Keller},
Intraspecific variability in social organization is common, yet the underlying causes are rarely known. In the fire ant Solenopsis invicta, the existence of two divergent forms of social organization is under the control of a single Mendelian genomic element marked by two variants of an odorant-binding protein gene. Here we characterize the genomic region responsible for this important social polymorphism, and show that it is part of a pair of heteromorphic chromosomes that have many of the key… 

The fire ant social chromosome supergene variant Sb shows low diversity but high divergence from SB

It is shown that the Sb haplotype of the supergene region has 635‐fold less nucleotide diversity than the rest of the genome, and how this reduction could be due to a recent selective sweep affecting Sb specifically or associated with a population bottleneck during the invasion of North America by the sampled population is discussed.

Social chromosome variants differentially affect queen determination and the survival of workers in the fire ant Solenopsis invicta

Evidence is found that the Sb variant of the social chromosome increases the likelihood of female brood to develop into queens and that adult SB/Sb workers, the workers that cull SB/ SB queens, are overrepresented in comparison to SB/SB workers.

Fire ant social chromosomes: Differences in number, sequence and expression of odorant binding proteins

This work identifies 23 OBPs in the fire ant genome assembly, including nine located in the region of suppressed recombination with Gp‐9, and identifies an additional OBP specific to the Sb variant of the region, which is consistent with multiple OBPs playing a role in determining social structure.

Evolution of Olfactory Functions on the Fire Ant Social Chromosome

It is suggested that the evolution of polygyne social organization involved adaptations in olfactory genes and opens the way for functional studies of the molecular mechanisms underlying social behavior.

Genome evolution: The social chromosome

  • M. Muers
  • Biology
    Nature Reviews Genetics
  • 2013
The authors found that the basis for the suppression of recombination is a large chromosomal inversion, and showed — using gene expression data — that most of the phenotypic differences between the two social forms result from differences in the non-recombining regions.

The fire ant social supergene is characterized by extensive gene and transposable element copy number variation

The results suggest that gene duplications may be an important factor leading to monogyne and polygyne ant societies.

Genetics: A social rearrangement

A large-scale analysis of the genomic region involved in fire ant polymorphism is presented and, surprisingly, the various aspects of this polymorphism are found to be governed by a non-recombining supergene occupying half a chromosome.

The social supergene dates back to the speciation time of two Solenopsis fire ant species

The formation of the supergene occurred concomitantly with the process of speciation of the Solenopsis socially-polymorphic clade, and it is hypothesized that the Sb variant first arouse in one incipiently-speciating population and then introgressed into the other populations or species.

The Pogonomyrmex californicus social niche polymorphism is a polygenic trait involving a young supergene

The results suggest that social morph in this species is a polygenic trait including an incipient supergene that evolved less than 200 000 years ago, and also finds remarkable differences to the other so far described social supergenes.




Information that reveals the links between molecular variation, individual phenotype, and colony‐level behaviors, combined with behavioral models that incorporate details of the chemical communication involved in regulating queen number, will yield a novel integrated view of the evolutionary changes underlying a key social adaptation.

Genetic control of social organization in an ant.

  • K. RossL. Keller
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1998
Findings reveal how a single genetic factor can have major effects on complex social behavior and influence the nature of social organization in the fire ant Solenopsis invicta.

Molecular evolutionary analyses of the odorant-binding protein gene Gp-9 in fire ants and other Solenopsis species.

A link between the presence of b- like alleles and the expression of polygyny in all South American fire ant species known to possess colonies of both social forms is confirmed and phylogenetic analyses show that b-like alleles comprise a derived clade of Gp-9 sequences within the socially polymorphic species.

Phenotypic Basis of Reproductive Success in a Social Insect: Genetic and Social Determinants

There is a counterintuitive relation between the potential and realized reproductive success of queens in multiple-queen societies of this ant, which is an unusual example of genotype-environment interaction in gene expression in which the environmental component is the social environment.

Identification of a Major Gene Regulating Complex Social Behavior

It is shown that single genes of major effect can underlie the expression of complex behaviors important in social evolution, and regulation of social organization by Gp-9 is conserved in South American fire ant species exhibiting social polymorphism.

Genome-Wide Expression Patterns and the Genetic Architecture of a Fundamental Social Trait

Fire ant Solenopsis invicta is characterized by a remarkable form of social polymorphism, with the presence of one or several queens per colony and the expression of other phenotypic and behavioral differences being completely associated with allelic variation at a single Mendelian factor marked by the gene Gp-9.

The genome of the fire ant Solenopsis invicta

A phylogenetic analysis revealed that an ancestral vitellogenin gene first underwent a duplication that was followed by possibly independent duplications of each of the daughter viteLLogenins, possibly reflecting differential selection acting on the queen and worker castes.

ECOLOGY AND EVOLUTION OF SOCIAL ORGANIZATION: Insights from Fire Ants and Other Highly Eusocial Insects

Evolution of social organization can be important in generating intrinsic selective regimes that channel subsequent social evolution and in initiating the development of significant population genetic structure, including barriers to gene flow important in cladogenesis.

Chromosomal rearrangements maintain a polymorphic supergene controlling butterfly mimicry

The results indicate that allelic combinations at known wing-patterning loci have become locked together in a polymorphic rearrangement at the P locus, forming a supergene that acts as a simple switch between complex adaptive phenotypes found in sympatry.