Ant Social Parasitism: Plot Twists in the Origins and Evolution of These Tiny Animals Revealed

Christian Rabeling, a researcher and associate professor of organismal evolutionary biology from the Arizona State University can now tell a story, specifically that of the evolution of social parasitism that's 30 million years in the making.

A Phys.org report said, Rabeling and his team which includes Marek Borowiec, a colleague and former post-doctoral researcher and now a University of Idaho assistant professor, and Stefan Cover, a long-term friend and colleague, safe keeper of the largest ant collection of the world at the Museum of Comparative Zoology at Harvard University, have now unveiled the most recent plot twists to understanding the origins and evolution of ant social parasitism.

A professor at ASU's School of Life Sciences, and a core researcher in the social insect group of the universities Rabeling explained, identifying the conditions linked to ant life history, and their transition from cooperative colony life to manipulative social parasitism is essential for understanding the manner behavioral changes are contributing to speciation.

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How Formica Ants Evolved

The professor said he is fascinated by social parasitism by first examining such behavior in leaf-cutter ants. And now, in his most recent study, he is studying Formica ants, one of the most varied groups of all.

The question he now asks is, "how did Formica ants evolve?" He explained that no one had ever carried out a detailed phylogenetic analysis that looked into the said issue.

First, as indicated in the study, published in the Proceedings of the National Academy of Sciences journal, a group of Formica ants, described in the Insect Identification site, lost their capacity to independently form the "hub of ant life," also known as colony formation.

The moment that ability got lost, a switch to a couple of other more multifaceted types of social parasitic behaviors occurred.

The researcher also explained that in the study, it was demonstrated that social parasites evolved from an ancestor that lost the capability of establishing new colonies independently and that extremely specialized parasites can evolve from less complicated social parasite syndromes.

And, as this report compared the said formula to most blockbuster Hollywood films, once it being successful, Rabeling discovered this same ant plotline was recurrently borrowed over and over again.

Social Parasitism

Describing social parasitism, Rabeling said it is a life history strategy evolving at least 60 times in ants, and over 400 socially parasitic species are identified from six distantly correlated subfamilies.

A similar report from the Museum of Comparative Zoology of Harvard University report said, out of 14,000 different species of ants to study, this researcher and associate professor chose one of the largest and the most diverse ant groups, as earlier mentioned, Formica ants.

As this study specified, there are more than 170 species within this genus or the so-called "supergroup," with half exhibiting social parasitic behavior, making it one of the Earth's largest.

The researchers' initial step to seeing a larger picture of Formica social parasites was to make a worldwide global evolutionary tree to understand further the historical links between species, as well as a window into the manner different species became social parasites.

The Formica Evolutionary Tree

To develop a Formica evolutionary tree which is also called phylogeny, the researchers looked at the DNA level to make branching associations between the Formica ants and insight into the inheritance of traits that regulate social behavior and diversity.

To do so, the team collected samples of DNA from over 100 Formica ants which represent all 10 known species groups across a worldwide geographical distribution. They also carefully calibrated the said data across evolutionary time.

As a result, the researchers found that the supergroup was one of the most successful in the history of the life of animals, first originating in the Old World approximately 30 million years ago and scattering several times to the New World and back as land bridges would come and go.

From their assessment, the researchers found that Formica last shared the same ancestor with Iberformica, its sister group, roughly 33 million years ago, and likely originated in Eurasia during the Oligocene Period following a long global cooling period.

Related information about Formica ants is shown on AntsCanada's YouTube video below: