Questions about ant ancestry (Pamela, New York, USA)

How far back does speculation go regarding the ancestry of ants? I have found that ants are thought to have come from wasps and I was wondering if speculation went further back to an ancestor for wasps etc. Is there a common ancestor that goes back to the sea?

Another question that I have is rather or not some wasps or wasp like creatures could have evolved from a line of ants, in other words the reverse of the theory that ants evolved from wasps?

Lastly, I am fascinated by ants that have an iridescent or blue hue and I found bees on-line that have an iridescent metallic green turquoise color. Is there an ant with a comparable appearance to this type of bee? Could these be related to the metallic bees? They look surprisingly alike.

Dear Pamela,

Ants and wasps are insects and are therefore members of the subphylum Hexapoda. Hexapods in turn belong to the phylum Arthropoda which includes crustaceans (crabs, lobsters, shrimp), myriapods (centipedes, millipedes), and chelicerates (spiders, scorpions, horseshoe crabs). All of these groups likely evolved from a shelled, aquatic ancestor. The evolution of land-dwelling behavior from aquatic ancestors appears to have occurred several times within this group. You should take a look at this study by Regier and colleagues and definitely check out Alex Wild's blog post discussing this paper.

Some of the strongest evidence that wasps are ancestral to ants and not the other way around is that the oldest known ant fossils are from about 100 million years ago, whereas the oldest known wasp fossils span back to around 150 million years ago. The changes in physical characteristics are also suggestive of a wasp to ant transition as an ancestral ant would mean that wasps had to reacquire wings and the ability to fly, rather than the far more likely loss of wings in ants. Lastly, phylogenetic analyses show that the ant clade (Formicidae) consistently nests within what we consider to be wasps, suggesting that ants are derived from a wasp-like ancestor (see this paper by Pilgrim and colleagues). All of this evidence taken together mean that it is far more likely that ants evolved from wasps than vice versa.

Ants and bees are related but every ant is more closely related to all other ants than they are to any bee. The same is true of bees in relation to ants. This means that the iridescent green color that is found in both ants and bees is a result of convergence to that character, not the close relationship of a particular pair of ant and bee species. In fact, there are many wasps that also have this type of coloration (see some of Alex Wild's beautiful photos here and here). These similarly colored species may use the same mechanisms for generating the necessary pigments, and these mechanisms may be present as a result of common ancestry but their expression is a result of convergent evolution.

Great questions!
Ben Rubin & the AntAsk Team

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