Monday, 26 March 2012

Ancestral Genes in Ants activated to form “Super Soldiers”


The theory of evolution is constantly being rethought as new evidence comes to light from scientific studies. Take the research team at McGill University, led by professor Ehab Abouheif,  who recently made the discovery that macroevolution can take place via the previously unrealised potential given by the “junk data” stored in DNA. Among the so-called junk is thought to be ancestral genetic information for traits that have been bred out over time. This DNA is sometimes activated, resulting in phenomenon such as “birds with teeth, snakes with fingers, and humans with ape-like hair” (Abouheif cited by McGill University 2012).

Abouheif’s team observed the activation of these unused genes in a colony of Pheidole ants on Long Island. Affected ants exhibited unusually large heads and bodies (pictured below), and were very similar to the sub-caste of “super soldier” ants that are naturally produced in the American Southwest (McGill University 2012). Such specimens, however, had never been observed in the Pheidole species until Abouheif’s study. This suggested that the ant was carrying genes from a common ancestor with the Southwest ants, which had somehow been activated. The transfer of this gene is demonstrated in the image below, which shows the various species of ant splitting off from each other, as well as the development and inactivation of the super soldier gene.

Attempts were made to reproduce the possible conditions that may have led to the super soldier’s creation by using hormones to trigger development of ant larvae (McGill University 2012). Success was met, indicating that the genes could be naturally activated. The research team went on to attempt the same treatment on several other ant species in which super soldiers had never been observed. In at least three other species, the super soldier sub-caste was successfully created, revealing the same ancestral data had been preserved in their genomes as well.

The discovery that these unused gene sequences can be activated under the right conditions is a huge leap for evolutionary theory, as natural selection may allow the potential given by these genes to be realised by the species, and allow for quick adaption that microevolution could not achieve (McGill University 2012). In essence, Abouheif’s study has revealed that the ancestral genetic information stored these species of ants may actually be able to provide a basis for macroevolution and rapid adaption. The presence of similar ancestral genes in other organisms – such as humans – poses the question whether such gene activation in also possible in other groups of organisms. If so, Abouheif’s findings may hold interesting consequences for genetics, and may be the start of a whole new area of experimentation.

Above: A regular Pheidole soldier ant (left) next to a “super soldier” (right).
(Alex Wild in McGill University 2012)

Below: The evolutionary tree of the various species of ant studied by Abouheif’s team. Those expressing the “super soldier” gene (XSD) and those not (SD) are shown. Those produced via laboratory processes are indicated via induction arrows.
(R Rajakumar et al. 2012)


REFERENCES

McGill University 2012, Back to the Future: Supersoldier Ants Illuminate Evolution,
viewed 17 March 2012,
.

R Rajakumar, D San Mauro, MB Dijkstra, MH Huang, DE Wheeler, F Hiou-Tim, A Khila, M Cournoyea, E Abouheif 2012, ‘Ancestral Developmental Potential Facilitates Parallel Evolution in Ants’, Science Magazine, Volume 335, p.79-82

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