Ant behavior: September 2014 Archives

Ant social status



Hi, I was curious if ants have a social status within their sub sectors (worker, male). How do they obtain a higher status? And if so does this give them more privilages (ie a bigger living space, more food, first breeding rights).

HUB


Dear Hub,

Thanks for writing to the AntBlog! We contacted an expert on many aspects of ant biology (behavior, colony reproduction, nest architecture, population dynamics, among others), Dr. Walter Tschinkel; here is what he had to say:

"Hello Hubert,
You asked AntBlog whether ant have social status within their colonies, and whether such status might be connected to certain individual advantages and benefits.
The simplest answer is that social status in the sense that we know it within vertebrate societies does not exist in ants. It is helpful to think of ant colonies as analogs to organisms (hence, we often call them superorganisms). Every individual is engaged in helping the colony produce more colonies, just as every cell in an organism is engaged in helping produce more of that organism. In the ants, there is only one (or a few) individual(s) capable of direct reproduction (the queen), while in an organism, only the germ-line cells in the gonads are capable of making gametes and subsequently more organisms. In this light, you can see that different sectors of the colony may be allocated differing amounts of resources, but such allocation serves the needs of the colony as a whole, rather than any individual within it. The individual ants making up the colony are simply the machinery needed to make more colonies.
One of the basic mechanisms that organizes colony function is division of labor (or function). The most basic division of function or labor is reproductive -- most of the ants in a colony are more or less sterile workers, while only one (or a few) individual is capable of mating and laying eggs. Most of these eggs develop into more workers because workers are short-lived and are continuously replaced, whereas the queen has a long life span (in many cases, equal to the life span of the colony). The second principle that organizes the colony is that the workers change jobs as they age. Young workers mostly take care of larvae and pupae, and as they age they switch to more general nest maintenance, food processing, transport within the nest and so on. Only the oldest workers leave the nest to forage, bringing back food for the rest of the colony. Once they begin foraging, their life expectancy is very short (a few weeks).
This change of jobs parallels an upward or outward movement of the worker within the nest. Young workers are born in the deeper parts of the nest, move upward as they age and change jobs, and finally appear near the surface, whereupon they become defenders and foragers during the last part of their lives. There is thus a continuous upward and outward flow of workers. The image here shows a cast of the nest of the Florida harvester ant, Pogonomyrmex badius, and summarizes these movement and labor patterns within the nest.

Once you see the parallels between organisms and superorganisms, you see that division of function or labor is central to both, and that differences in allocation serve the entire entity. The relative size and activity of the liver, or kidneys or circulatory system of an organism serves the entire organism, and any deviation from some norm can be detrimental to the function and fitness of the organism. Similarly, the patterns of division of labor in ant colonies serves the success and fitness of the colony as a whole. The workers are just the gears in that machine."

We hope this answers your question,

Walter Tschinkel, Flavia Esteves & the AntAsk Team

Cohabiting ants


Hi there, loving your page!

I am on holiday in Andalucia, southern Spain, and right by our front door there is a colony of what look like harvester ants. No more than fifteen centimetres away there are some holes from which some very tiny red ants emerge, about a quarter of the size of the smallest harvester ants. Are these two separate colonies, or different types of the same ant? They don't look related and they don't appear to cross into each others territory. I would have thought they'd be fighting all the time if they're not related. Why might this be? Are their diets different enough that they aren't in competition? Sorry to bombard you with questions!

Kind regards,

Ian


Dear Ian,

Greetings from San Francisco, and thanks for writing! We contacted an expert on taxonomy and ecology of Europe and Macaronesia ant species, Dr. Xavier Espadaler; here is what he had to say:

"It is not an unusual situation for different ant species to have nest entrances rather close. Coexistence is a possibility; fighting is another possibility. But if the two societies are already nesting close to each other, it is likely that they differ in some way, in their daily activity cycles, or in their food habits.

It is possible that the harvesting ants (Messor) are living close to a Pheidole pallidula nest. This last species is all too common in AndalucĂ­a. Their nest, with one or a few entrances, is usually surrounded by the tiny remains of the scavenging they do upon any kind of arthropod remains or corpses; they may capture living prey as well, if small enough. The remains look like a dark zone, somewhat semicircular, bordering the nest entrance. If you are able to look at them under a magnifier, you would see shining heads, wing or leg or thorax fragments, that are the non edible parts of their foraging."

Hope this helps,

Xavier Espadaler, Flavia Esteves, & the AntAsk Team

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