4 replies to this topic

[futurebird]

Lasius brunneus are little brown garden ants that are not thought of as "having castes" … most ant guides will describe all their workers as "all the same size."

However, these photos from antiwiki show the size difference in workers from a mature colony vs. nanitic workers. The nanitic workers are small since their initial nutrition must come in its entirety from the body of the queen!

Do you have enough mass in your body to make three or four people to help you out? I don't!

 

https://www.antwiki....Lasius_brunneus

I've edited the image to compare all of the ants together:

 

 

 

[Stubyvast]

Nope, me neither thank goodness! I'm not that huge.

 

Yeah it could be confusing, I mean my Lasius Niger colony does seem to have "no castes" besides queen, male, and worker. However, I think that the caste difference is just hard to notice until you observe closely. For example, my colony seems to mostly to have workers in the "Later Nanitic Worker" caste, probably because of a lack of threats, constant food supply, and a small colony size of about 100 workers (not for long though, the brood pile is getting huge). But if you compare this to the same species, which I found outside, 90% of these ants are all "Typical Worker of Mature Colony," perfectly adapted to predators, aphid tending and protecting, and the overall environment. I bet the variety of food they find out there probably helps, as well as the size of the colony. Very interesting stuff!

 

But you are correct, they do have castes, but they are simply less noticeable. This wouldn't quite qualify as "minor polymorphism" found in formica obscuripes, among others, or simply "polymorphic" such as ​Camponotus modoc, or the "Extreme polymorphism" in pheidole calafornica, with their massive classes of majors, that can be as big or bigger than the queen. Lasius brunneus, and ​Lasius niger, both neglect to produce the specialized major class, unlike other ant species. 

[bmb1bee]

These don't really count as extra castes. Nanitics are really just smaller workers due to the lack of nutrients. Antwiki doesn't have nanitics listed under the list of castes I believe. True castes refer to terms like minors, medians, majors, and supermajors.

 

https://www.antwiki....inology#Workers

[Artisan_Ants]

I belive species with "no castes" are referred to as monomorphic like L. Niger and brunneus but speaking of this, it's quite interesting as they aren't listed as castes cause of you think about it, the more abundant food is to a colony, the more workers and also the larger the workers like in futurebird's example of L. brunneus sizes. The thing is, for polymorphic species, they also need abundance of food (primarily protein) to develop such large majors and their workers also follow the larger minor worker thing that monomorphic species follow. I guess the reason myrmecologists do this is to make it easier to sort out the various size differences of polymorphic and monomorphic species. It would be annoying to make names specific names for every size or castes cause or makes more confusing than what ants already are (as a compliment to the various things ants already have already done and accomplished). It also generally makes it confusing as myrmecologists have to note down and write down about certain scies as well as citate certain sources on things like Antwiki and AntWeb so not including specific castes just makes these jobs easier.

[Mettcollsuss]

I was actually just researching a similar topic. For a while I had assumed nanitics were just the extreme low end of the worker caste's allometric variation, underdeveloped/stunted due to limited resources. However, according to the literature I've seen so far, they are more distinct than I had expected. A study by Watanabe et al., 2017 on Camponotus obscuripes showed that the nanitic workers were distinct from mature workers: when various allometric traits were put on scatter plot graphs, the nanitics clustered together and often had relatively little overlap with the proportions of mature workers, and followed a different allometric slope and growth rules than mature workers. They conclude that C. obscuripes has diphasic allometry rather than the previously believed monophasic allometry.

 

What exactly constitutes a caste varies greatly depending on who you ask. However the general consensus, to my knowledge, is that worker castes should be fully separate and not upon the same allometric scale, without intermediate forms, and often also with some distinct recycled or novel trait(s) and often some sort of change in epigenetic expression. Some people, like the paper I linked above, may consider nanitics to be a separate caste, some may consider them a subcaste, it's largely just semantics. However, to address the initial point of this thread, when a species is said to be monomorphic, dimorphic, polymorphic, etc., it's referring to the distribution of worker castes in a mature colony; Since many, if not most, species have a nanitic caste/subcaste, it's not particularly useful to include when discussing more general caste variation between species.

Edited by Mettcollsuss, July 24 2024 - 10:09 AM.