The team published their findings in this months issue of Molecular Phylogenetics and Evolution.
Using a hypothesis of the evolutionary relationships among antbird species that we reconstructed from DNA gene sequences, what we found is that army-ant following has been around a long time, possibly as long as six million years, and that its evolution followed a logical progression from least specialized to most specialized, said Brumfield.
There are three main categories of specialization found in army-ant-following birds. The first, called occasional army-ant followers, are the most casual of the three, utilizing the insects to round up food but only as the swarm passes through their territory. Regular army-ant followers, the next level up in specialization, will follow the army ants outside of the flocks territory but are not completely dependent on the ants to provide food. These birds regularly hunt for themselves. The final, and perhaps most interesting, category is that of the professional army-ant followers. These birds are completely reliant on the army ants for food, presenting a problem almost as unique as the situation itself.
These birds depend almost solely on one species of army ant, called Eciton burchellii, said Brumfield. This makes the professional army-ant followers sensitive to many of the very real threats to this ecosystem, like deforestation, global warming and other similar issues. If anything affects the ant population, it could be devastating for these birds. But what is perhaps most surprising is that, despite the birds dependence on one primary ant species, the specialization has persisted for millions of years.
|Contact: Ashley Berthelot|
Louisiana State University