'Frozen behaviors' in amber fossils: How to reconstruct mating behavior of long-extinct termites
Approximately 38 million years ago two termites were in the middle of courtship behavior when they got entrapped by tree resin and preserved in fossilized amber. This, so far, oldest and only-described fossil of an Electrotermes ...
The discovery of this rare fossil was a strike of luck. Dr. Ales Bucek, currently the head of the Laboratory of insect symbiosis at the Czech Academy of Sciences, immediately recognized the scientific value of this piece of amber when he saw it in an e-shop for fossil collectors. "Termite fossils are very common, but this piece was unique because it contains a pair. I have seen hundreds of fossils with termites enclosed, but never a pair," explains Dr. Bucek.
After purchasing the fossil, the team of the OIST Evolutionary Genomics Unit used an X-ray micro-CT to get a better look at the E. affinis pair embedded in the amber, "identifying the species was actually not easy, because there were bubbles in front of important parts of the termite's bodies," Dr. Simon Hellemans, a postdoctoral researcher at OIST, says.
The scan revealed not only to what species the insects belonged but also that the trapped individuals were a male and female laying side-by-side with the female's mouthparts touching the tip of the male's abdomen. An image the researchers were familiar with, as they observed it many times in current day termites engaged in a behavior called tandem running. During this mating behavior the insects display coordinated movements which ensure that the pair stays together while exploring a new nest-site.
This close-up picture of the fossilized termites shows the parallel positioning of the two individuals encased in the amber. The larger female (left) is still touching the smaller male (right). Credit: Aleš Buček (OIST/The Czech Academy of Sciences)
This pair of E. affinis termites was trapped in tree resin almost 40 million years ago and preserved until today in a Baltic amber fossil. Credit: Aleš Buček (OIST/The Czech Academy of Sciences)
Current day termites form a straight line when running behind each other. During the tandem run, one partner keeps contact with the other using their antenna or mouthparts, to make sure they stay together while exploring a new nest site. Credit: Aleš Buček (OIST/The Czech Academy of Sciences)
With the resin flowing slowly down the tree, the termites get trapped on the sticky surface and might eventually turn into an amber fossil. Credit: Anna Prokhorova (OIST/ The Czech Academy of Sciences)