Ants have been populating Earth for millions of years, and their evolution and behavior have always intrigued scientists. Although we know they've been around since the Cretaceous period, 130 million years ago, the ants we see today are very different from their ancestors.
These insects are known to have diversified and spread in almost all environments, yet there is so much more we need to learn about them. One particular ant, recently found in the soils of an Amazonian rainforest, stands as an example of how some of these insects have evolved, or in this particular case, not evolved.
The “ant from Mars” is the sole representative of a morphologically distinct subfamily of ants, the Martialinae, and has been described as a “cryptic predator” corresponding to a sister lineage separated from today's ants.
A detailed analysis of the “ant from Mars” revealed that although it is clearly a member of the family Formicidae, like all ants, they have a distinct morphology that places it in its own subfamily.
These intriguing ants have given a lot of trouble to scientists, especially considering the fact that they've been practically re-discovered, after five years ago two worker ants were found and subsequently lost.
Its anatomic distinctiveness, such as the lack of eyes, or the pale integument, suggests that the “ant from Mars” is actually well adapted to a low-light environment, such as leaf litter or rotting wood, and that the ant is a forager, perhaps surfacing at night.
The long front legs made scientists speculate that they are used less for digging activities, and more for pray capturing, perhaps annelids, termites, insect larvae and other similar soft-bodied arthropodes. However, these are mere assumptions, as scientists still know very little about the mysterious ant.
The DNA tests on the “ant from Mars” revealed that the Martialinae separated into a distinct subfamily of ants over a hundred million years ago, and suggested that the most basal extant ant lineages are in fact cryptic foragers, which contradicts earlier associations with wasp-like foragers.
The new study led scientists to believe that as these ants adapted to the subterranean environment, their biology and morphology suffered insignificant changes in evolutionary terms due to the fact that this environment was not only an ecologically stable one, but it also provided them with a safe refuge, keeping them from competing with other ants.
However, according to scientists involved in the study, the new assumptions do not exclude the possibility that the ancestral ant was at some point a wasp-like, large-eyed forager, rather than a blind, subterranean predator.
According to them, the findings are congruent to the dynastic succession hypothesis, which proposes a ground-associated ant ancestor derived from a wasp-like predator that radiated into specialized soil, leaf litter and arboreal habitats.
“This discovery hints at a wealth of species, possibly of great evolutionary importance, still hidden in the soils of the remaining rainforests,” the study says. The findings, signed by Christian Rabeling and colleagues, appear in the journal Proceedings of the National Academy of Sciences.
