Abstract
One of the most novel foraging strategies in Neotropical birds is army-ant-following, in which birds prey upon arthropods and small vertebrates flushed from the forest floor by swarm raids of the army-ant Eciton burchellii. This specialization is most developed in the typical antbirds (Thamnophilidae) which are divisible into three specialization categories: (1) those that forage at swarms opportunistically as army-ants move through their territories (occasional followers), (2) those that follow swarms beyond their territories but also forage independently of swarms (regular followers), and (3) those that appear incapable of foraging independently of swarms (obligate followers). Although army-ant-following is one of the great spectacles of tropical forests, basic questions about its evolution remain unaddressed. Using a strongly resolved molecular phylogeny of the typical antbirds, we found that army-ant-following is phylogenetically conserved, with regular following having evolved only three times, and that the most likely evolutionary progression was from least (occasional) to more (regular) to most (obligate) specialized, with no reversals from the obligate state. Despite the dependence of the specialists on a single ant species, molecular dating indicates that army-ant-following has persisted in antbirds since the late Miocene. These results provide the first characterization of army-ant-following as an ancient and phylogenetically conserved specialization.
| Original language | English |
|---|---|
| Pages (from-to) | 1-13 |
| Number of pages | 13 |
| Journal | Molecular Phylogenetics and Evolution |
| Volume | 45 |
| Issue number | 1 |
| DOIs | |
| State | Published - Oct 2007 |
Funding
Studies such as this would be impossible were it not for the long-term efforts of ornithologists working at great expense to collect samples from remote corners of Central and South America. For collecting tissue samples of the species used in this study, we are extremely grateful to the collectors and specimen preparators whose names appear in Table 1 , and to the curators and collections managers of the Louisiana State University Museum of Zoology (LSUMZ), the Field Museum of Natural History (FMNH), University of Washington’s Burke Museum of Natural History (UWBM), the United States National Museum of Natural History (USNM), and the University of Alaska Museum (UAM) for loaning to us the tissues used in this study. For comments on the manuscript or assistance in the lab we thank J. M. Bates, J. Blackwell, A. Curtis, K. Feldheim, S. J. Hackett, J. Prejean, J. V. Remsen, F. H. Sheldon, and four anonymous reviewers. The map data were provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy—Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE. This research was supported by National Science Foundation Grants DEB-0543562 and DBI-0400797 to R.T.B., and INT-0135532 to J.G.T and J. M. Bates.
| Funder number |
|---|
| INT-0135532, DEB-0543562, DBI-0400797 |
Keywords
- Ancestral character state reconstruction
- Army-ant-following
- Eciton
- Ecological specialization
- Foraging strategies
- Thamnophildae