Ant origins, and beyond...



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?

Pamela

Dear Pamela:

It is fortunate that good answers to at least some of your questions have recently made it into the scientific literature. Let's take them in order:

Regarding distant ant ancestors in the sea, several years ago, David Grimaldi of the American Museum of Natural History published "Evolution of the Insects", an exhaustive treatment of the origins of modern and the many known fossil insects. Grimaldi and all others who have studied the matter conclude from the evidence that the common ancestors of all insects were terrestrial. A number of ancient and modern insect lineages have evolved to live in water for at least part of their life cycle. However, these groups all evolved from terrestrial ancestors. With only a very few exceptions, all aquatic insects live in fresh water, not in the seas, and the few marine insects originated from fresh water ancestors. For a discussion of the evolution of the larger group that contains insects, the arthropods, and where insects fit in this very diverse group, see this blog concerning a recent publication on arthropod-phylogeny. This study indicates that farther back in time, before the insects evolved, all arthropods were marine.

Only much more recently, the wasps, ants and bees arose as a group from more distant, but decidely terrestrial ancestors that looked like insects we call sawflies, also in the insect order Hymenoptera, but with a much older fossil record. There is virtually no question that ants have a common ancestry with wasps and bees, but that each of these named groups have remained separate since the original split. The oldest known ant fossils are dated at just about 100 million years old, but ants as a group are estimated to date back to between 110-130 million years. All available fossil and genetic evidence indicates that since ants originated, only what we could call other ants have evolved from ants, while all modern wasps, since the long-ago evolutionary split from the ants, have evolved from wasp-like ancestors.

And finally, there are indeed a number of ants that have iridescent purple or green reflections. The most striking examples are in the Australian ant genus Rhytidoponera. Once you click on this name, scroll down to R. purpurea for a particularly good example, but others will be worth a look, too.

James C. Trager of the Ask Ant Team

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