A Dominant Dolichoderine

Anonychomyrma workers aggressively defend the carcass of a carpenter ant they have found from would-be usurpers.

Several years ago Australian myrmecologist Alan Andersen proposed a set of categories for arranging ant species by “functional group“. These groups carried names like “cold-climate specialists,” and “subordinate camponotines,” and they were widely adopted by ecologists for their ease of use. The scheme also drew considerable ire from taxonomists, especially since the categories were somewhat arbitrary and many blended behavioral and taxonomic attributes.

Another issue was that these groups, crafted from Andersen’s knowledge of the Australian fauna, didn’t always make sense outside of Australia. Certainly the “Dominant Dolichoderines” were aptly described on the great southern continent. Any stray bit of picnic lunch in Australia is nearly instantly covered by ravenous and aggressive Iridomyrmex. But do the same functional categories apply to the more timid dolichoderines of Europe?

I’m not sure.

In any case, the Aussie genus Anonychomyrma fits the bill of a dominant dolichoderine. Here are couple recent photos of Anonychomyrma defending their title.

Anonychomyrma workers cooperate to transport the body of a dead carpenter ant.
Portrait of an Anonychomyrma worker.

18 thoughts on “A Dominant Dolichoderine”

  1. I think the three main problems with using functional groups or guilds are (a) that they replace any deeper understanding of the constituent species with a buzzword, (b) people tend to believe they are real ecosystem units rather than arbitrary groupings, and (c) they imply purpose. I think the stream ecology people have made the best use of functional groups, but even there one gets the feeling that, e.g. all scrapers are equivalent and there to do an ‘ecosystem service’.

    A third, somewhat lesser, problem is that the groupings are arbitrary in both an ecological and taxonomic sense and in effect isolate the taxon or taxa from other influences. For example, Richard Root’s original guild of ‘foliage gleaners’ referred only to birds. How about bats, robber flies, dragonflies, and assassin bugs? Don’t they glean insects from foliage? You can’t study everything, but surely these other foliage gleaners influence the dynamics of the bird populations.

    1. You make some good points BUT all human categories including those of standard taxonomy eg genus and species are arbitrary groupings to a greater or lesser extent. I include standard taxons because what a taxonomist might segregate into a species could be just as arbitrary as guilds.

      Take for instance the segregation of Polar Bears from Brown Bears. Since viable hybrids of the two populations are very well known even if rare in human viewpoint, from the “bear’s point of view” and in terms of genetic exchange, they are merely subspecies of the same species.

      The take-away point is that everything human is arbitrary but if it’s useful then we can use it, keeping in mind a good man always knows his limitations.

      1. Yes, but to channel Orwell, some arbitrary groupings are more equal than others. I was trained as a Biological Species Concept student, but I’ve come to see the BSC as mostly BS. Gene flow between different kinds of animals and plants is extremely common and alone is no reason to start calling them the same kind. I’ve described many species (and also guilds), but I think of them as hypotheses that having a new name is useful for understanding what you can expect them to do, not that I have a magic insight into the workings of the Universe. Proposing an ecological unit based only on taxonomy seems on the mystical side to me. For this to work, at a minimum, the interactions within the taxon would need to be orders of magnitude greater than among taxa.

        1. I think it’s a bit too far to claim BSC as bullcrap but I would agree that there are difficulties with any human construct, which was my original point. Certainly this entire approach to species is close to useless in the case of asexually reproducing organisms commonly using promiscuous lateral genetic material exchange.

          As far as Guilds go, as an actual student of Root, I concluded that his construct of Guilds was a concept-structure useful in explaining how multiple (sometimes completely unrelated) species interacted with their environment in the same way and helped explain sets of homologous adaptations. Root would have been the first to include insects, birds, whatever else in any particular guild concept, and as I recall, he DID. He was pretty wild & wooly, actually.

          And as I concluded before, I still say that if your functional group has utility, go for it, as long as you know the guaranteed fuzzy limits of your concept !. After all, wing are for flying no matter from what body part they evolved from, if you get my point.

        2. I am inclined to agree with both you guys.

          These “groups” have heuristic value even when they are arbitrary. This is especially true at the murky beginnings of a study, as they can guide research until it becomes apparent that a more precise metric is needed.

          I dislike Andersen’s ant functional groups for more developed studies because they confuse taxonomy with behavior. Stable isotope analysis provides a more quantitative assessment of community trophic structure, and phylogeny a more objective assessment of historical relationships. Depending on the nature of the question being asked, these or other objective metrics are capable of providing a much more useful, replicable, and transparent answer.

      2. Hi BioBob,

        I took Insect Ecology from Peter McEvoy, another student of Root’s if I recall correctly. Also, I did corner Root at one Ecol Soc meeting when I was a postdoc all full of fire and brimstone and as I recall he didn’t disagree with my points (or he couldn’t find a security guard to save him), only claimed he had other purposes. If you are referring to his collard arthropod guilds, though, then I think they had the same taxon-first bias.

        RE the BSC, I don’t think it has much currency among biologist outside the less critical ornithology-mammology cliques anymore. It simply doesn’t work and when the premises of a theory have been refuted, it is time to move on.

        1. I am always happy to entertain different points of view on how one defines the evolutionary unit and it’s expansion into the larger species concept. But, imo, many problems with BSC lies with we humans – our definitions, capabilities (or their lack) and biases, not with the genetic bounded population which is it’s consequence. The particular organism always defines the species, not us, and ‘nature’ is always stranger and more inscrutable than we think.

          Feel free to suggest viable alternatives to BSC – I am all ears.

          Peter McEvoy – I seem to recall that name sitting in classes, lurking in sympatric hallways, lol.

        2. I should have noted that Peter’s Insect Ecology was one of the best classes I ever took.

          In my not at all humble opinion, when a hypothesis has been falsified, it needs to be dumped. There isn’t much ‘genetic isolation’ in nature and it doesn’t define ‘real’ evolutionary units. Real life is far more complicated. I’m a nominalist myself, but I’m willing to use phylogenetic species hypotheses. At last count, there were 28 competing species concepts in the literature – take your pick.

  2. Interesting piece, as always, but “they were widely adopted by ecologists ” is a bit of an overstatement. I would say more like “they were briefly used by a handful of ecologists”…

  3. Nice to see some comments with meat from Dave and BioBob…pity I don’t have a clue what they’re talking about!

    Nice pic’s Alex, seeing an ants eye-view of their behaviour is always a treat!

  4. Well, clearly this Anonychomyrma seeks domination – It’s profile looks like Darth Tapinoma!

    A good example of how confusing these categories are is the 1954 movie “Naked Jungle”, which totally confused the ecological functions of leaf cutter ants, army ants, and subordinate camponotines.

    But seriously, I had some correspondence with Andersen about his scheme several years ago, in which we came to agree, (I think – well anyway, I agreed), that the scheme could (needed to) be tweaked for geographic regions outside of semiarid, subtropical Australia.

    My foremost objection to it is that “functional” implies ecological-behavioral to me, and the taxonomic labels simply confuse the matter. Another problem is that in much of the world, few or no dolichoderine ants have that “top dog” function within the ant species assemblages of the places they inhabit. On a local basis, particular species of Formica, Solenopsis, Camponotus or other genera may be the functional dominants. Further, I can’t think of a single example where all or even most of the species of any of these genera occurring in a place are dominant, as Andersen delimits them in the eco-behavioral part of his description of the groups. So, one really must simply leave taxonomy out of it.

    I find the cryptic group extremely simplistic. The functional roles of the cryptic yellow Lasius, Acropyga are as different from those of Strumigenys, Leptogenys, Amblyopone as are those of attines compared to army ants.

    From time to time, I receive manuscripts attempting to squeeze local ant faunas of say, Midwest tallgrass prairie or Italian oak woodlands into Andersen’s scheme. When the authors haven’t already done so, I always suggest they give due respect to Andersen, then modify their classification to 1) eliminate any taxonomic modifiers and 2) fit the real, observed functions and interactions of species the ecosystem they are studying.

    1. James, I think I pretty much agree with you and to a degree with BioBob (not on on the BSC though) and Alex. I haven’t seen Alan for years, but one of the things I always liked about him was his willingness to stir the pot. The sad thing is that most people seem to want to think inside the box and to glom onto other’s hypotheses and promote/defend them without critical thought. Thus, instead of advancing in our understanding of systems, dogma fixates on a popular idea and we become cast into a Kuhnian hell.

    2. I don’t have much to add to this, other than to say I appreciate your thoughtful take on the issue, James.

      I always thought it odd that most of our North American ants would be “cold-climate specialists”, even though the various species are clearly trophically and behaviorally different.

  5. I’m a bit late in here with comments – but the FG scheme doesn’t work across pretty much the entire continent of Africa either….
    I agree with James that one of the problems is the reference to ‘function’, when in reality it doesn’t enter much into the classification at all.

  6. Pingback: Links 2/15/12 | Mike the Mad Biologist

Leave a Reply