Now and then you come across a research paper that changes your perspective, and offers you a view into ecological interactions that, at first glance, seem unbelievable. Such was the case last week in my graduate class in Forest Entomology. One of the students led a discussion of a paper titled “Defensive plant-ants stabilize megaherbivore-driven landscape change in an African savanna”. It’s an elegant paper about the interactions between elephants, ants and trees. It was published in Current Biology in 2010.
This is not a particularly new story – it was actually discussed on a number of blogs quite a while ago:
Here: http://blogs.scientificamerican.com/observations/2010/09/03/wee-ants-protect-african-savanna-trees-from-elephants/ …by the way, that journalist failed to spell the primary author’s name correctly. Unacceptable…
And Conservation Magazine did a write-up on the research:
Here’s a quote from that article: “Pitting ants against elephants doesn’t seem like a fair fight. But according to a study in Current Biology, these humble insects can act as mighty “bodyguards” that prevent elephants from munching trees on the African savanna”
The take-home message from the research is something like this:
Elephants suppress tree cover in the Savanna, and their intense feeding behaviour can alter the landscape composition of trees. However, some species of trees, on some soil types, have symbiotic relationships with ants (genera Crematogaster and Tetraponera). Though a series of well-designed experiments (i.e., manipulative and observational), the authors (Jacob Goheen and Todd Palmer) show that the ants are able to effectively defend some trees from these mega-herbivores and thus are indirectly affecting the tree composition at a landscape scale. It’s a story of ants, elephants, and the Savanna landscape.
For a visual, here’s a nice photo of Crematogaster ants from Florida (thanks to Alex Wild for permission to post his image here)
So, what makes it worth revisiting this paper, now, and why is this paper and topic particularly interesting?
Well, two things came up in the discussion last week that have prompted this post.
1) It’s “Clash of the Titans” NOT “David and Goliath”. Some of the aforementioned posts seem to like the whole “little ant takes on those big elephants” angle. I just don’t think that is an appropriate analogy. To be fair, an individual ant is certainly small compared to an elephant (and the authors of the research paper are quoted along these lines), but in terms of overall biomass, ants rule. For example, it is argued that ants make up 15-20% of terrestrial animal biomass! Furthermore, globally, I would argue that ants play a much more important functional role in many ecosystems than most vertebrates (although perhaps a proportionately greater effect in tropical regions). Don’t misunderstand – I love elephants as much as the next person… but they are not the Goliath in that article. In this paper, the Goliath was always the ants, and Goliath wins.
2) Another interesting point came up in our discussion. The story is fascinating, the science is strong, and to the broader community of biologists/ecologists, it was new. However, to the local people that live with and observe these interactions everyday, it’s probably not surprising, nor is it likely anything new. It’s one of those cases of a ‘stunning’ discovery that, when speaking with natural historians, and people that live in proximity of the study area, may not actually be ground-breaking. Let me be clear: I am NOT saying this shouldn’t be published, nor am I criticizing the science of this paper. Instead, I wish to merely point out that there’s a good chance that behind these types of studies are probably a group of people who may find it quite surprising that a bunch of scientists are getting excited about an everyday, common occurrence. This is something to keep in mind as we work to publish our latest, newsworthy results.
Here are some more links:
One of the authors (T. Palmer) for this study writes science blogs for the Huffington Post: http://www.huffingtonpost.com/todd-palmer-and-rob-pringle
And if you like ants, go here and browse: http://www.alexanderwild.com/