Biodiversity and life history adaptations of army ant symbionts
Final Report Abstract
Over the last decades, biologists have begun to explore the last biological frontiers, from the deep sea to tropical rainforest canopies. Despite these efforts, such frontiers of largely unexplored biodiversity still exist today, albeit on a smaller scale. One example is the microcosm of myrmecophiles associated with tropical army ants. For instance, more than 300 myrmecophile species, primarily arthropods, are associated with a single species of Neotropical army ant, Eciton burchellii. It is clear, however, that this is only the tip of the iceberg and that many more species await scientific discovery and formal taxonomic description, especially because myrmecophiles of other army ant species are notoriously understudied. Furthermore, very little is known about the myrmecophiles’ life cycles and basic life history. I study the myrmecophile community associated with six Eciton army ant hosts at La Selva Biological Station, Costa Rica, by combining DNA barcoding for rapid species identification with detailed taxonomic descriptions. For each specimen, I provide species name, DNA barcode, a voucher, and digital voucher images, as well as detailed collection records. Such a reference database forms an essential baseline for further studies of these complex myrmecophile communities. A group of staphylinid beetles (genus Vatesus) exemplifies the benefits of our approach well. Our DNA-based species identification protocol uncovered cryptic species in this genus, and thereby provided evidence for unexpectedly high host specificity. Using DNA barcodes to match larval and adult stages, we demonstrated that both adults and larvae of all Vatesus species participate in colony emigrations. Furthermore, dissection of ovaries from Vatesus females combined with an evaluation of the presence of different larval instars nicely demonstrated that reproduction and larval development are remarkably well synchronized with the hosts’ stereotypical colony cycles, which alternate between a nomadic and a statary phase. Besides revealing the biodiversity and life history adaptations of army ant myrmecophiles, a large-scale comparative analysis of different myrmecophile taxa will also unveil general evolutionary trends and the community structure of this diverse multi-species network. Preliminary results indicate that this army ant-parasite network is significantly structured. It shows a higher degree of specialization than typical predator-prey or non-symbiotic networks, indicating high host dependencies of parasites and a shared evolutionary history of the partners. In addition, this network is highly modular, i.e. parasite groups cluster around phylogenetically closely related host species, indicating a strong effect of phylogeny on host-symbiont interactions. This project already has uncovered an important and understudied component of tropical biodiversity and further studies of the whole myrmecophile community might contribute to our general understanding of ecological and evolutionary dynamics in complex host-symbiont networks.
Publications
- (2015). Interbreeding among deeply divergent mitochondrial lineages in the American cockroach (Periplaneta americana). Scientific Reports, 5:8297
von Beeren C., Stoeckle M.Y., Xia J., Burke G., and Kronauer D.J.C.
(See online at https://doi.org/10.1038/srep08297) - Studying the Complex Communities of Ants and Their Symbionts Using Ecological Network Analysis. Annual Reviews of Entomology Vol. 61:353-371, March 2016
Ivens A.B.F., von Beeren C., Blüthgen N., and Kronauer D.J.C.
(See online at https://doi.org/10.1146/annurev-ento-010715-023719)
