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G. portentosa body types


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It seems to me that there are two distinct body types that exist in G. portentosa. There are thinner, laterally, and longer individuals and then thicker, shorter individuals. I’ve noticed it in males and females. It’s harder to see in females since they become so distended with young as they approach birth but even in taking that into account, I can see it (maybe). Would anybody agree or disagree with this hypothesis?

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It seems to me that there are two distinct body types that exist in G. portentosa. There are thinner, laterally, and longer individuals and then thicker, shorter individuals. I’ve noticed it in males and females. It’s harder to see in females since they become so distended with young as they approach birth but even in taking that into account, I can see it (maybe). Would anybody agree or disagree with this hypothesis?

I think I'm seeing the same thing as you. I've got long(3"), cylindrical ones, almost cigar shaped and then I've got short (2-2 1/4"), laterally compressed, very flat and wide. The short, flat ones are usually lighter colored and the longer, cylindrical ones are usually darker. These are the two extremes and there are a million variations between the two. My whole colony is based on three very "average" looking individuals from 1992. I'll try for some pics tomorrow. I'll have some time off over the holidays and my camera and my roaches are going to get a work out. So far (which is not very far for me), all of my other species seem pretty homogenous by comparison.

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Doesn't that just have a lot to do with feeding/how much certain individuals eat? Or am I missing something?

Bingo! We have a winner.....

The shape of the hisser has nothing to do with a "body type". Its body shape will vary mostly based on these three variables:

Male or female.

How recently it molted and where it is in its growth cycle.

Well fed and hydrated or not.

With any colony you should get plenty of variations in body shapes (or not) as not all the roaches will eat the exact same amount at the exact same time, nor will they molt at the same time or even grow at the exact same rate..... in theory you should have at least 6 different "body shapes" in a colony. More really because a female may be heavily gravid or not as well (which can add to the distinct 'cigar shape' a really fat female can have. This is true in all roaches but not nearly as obvious as it is in hisser types (particularly over fed hissers).

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I have one old male who's been distinctly tubular his entire life. In one instance a few years ago, the tube shape was attributed to a maggot-like creature which was expelled from the male's body and later died. This guy has no parasites though, I'm sure of it.

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Hi

I made the observation that this two shapes show up in medium sized nymphs already and don't depend on the amount of nutrition IN the roach (one couldn't blow up a 'flat' one the way it would look 'cylindrical' afterwards and the later doesn't get the same 'flatness' when starving). It might though depend on environmental facts and not genetics but I've seen with my first two females or better their first offspring that the youngs form the 'cylindric' and those of the 'flat' one were similar to their mothers shapes. In addition the two females have a different color which they inherited. My culture should be 'pure' cause it was imported from Madagascar by the zoo Zurich around 10 years ago and as I've been told weren't mixed with other hissers till now. Now that I have several reproducing individuals I can't tell which offspring comes from which parents but there still is a clear difference in shape (there is some variation but one can easily split the roaches in two groups) whereas color and pattern show up in every nuance.

I never reflected about that and took it as the natural variability of this species.

Oh... 'Princisia vanwaerebeki Black&White', Aeluropoda insignis, Elliptorhina chopardi, and the alleged G. oblongata don't show this difference in shape.

Grüessli

Andreas

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It seems to me that there are two distinct body types that exist in G. portentosa. There are thinner, laterally, and longer individuals and then thicker, shorter individuals. I’ve noticed it in males and females. It’s harder to see in females since they become so distended with young as they approach birth but even in taking that into account, I can see it (maybe). Would anybody agree or disagree with this hypothesis?

I'm expecting Orin to drop the hammer and set us all straight any time now, but...

As Pharma noted, its not about food and I don't see how inbreeding would cause variation in body type. Wouldn't inbreeding cause homogenization like in all of our dog breeds? These two body types are very obvious even in my small nymphs of less than half an inch. While I have these two extremes, I also have many in-betweens. Today I fed out about 30 smallish nymphs to my monitor babies and the color variations seem randomly spread between these two types too. Here's another thing to add to the mix. Apart from appearance, do you notice behavior differences too? For example, I've got jumpers and I've got clingers. Some of them will continually take a suicidal leap out of your hand and others run to the edge just as fast, but turn around or run upside down on the other side of your hand, but won't jump off no matter what. The jumpers just jump right out of my hand and into my lizard feeding bins and the clingers are hard to get off your hand. In the case of hisser's these things seem to me to be just natural variations within the species. I'll post pics asap.

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Behavioral differences are definately there. "Personalities", if I may. A good way to see this is to move a group of hissers into a new environment, then again once they are settled into that one. The same roaches will either cluster together or go out and explore. I've also noticed different food preferences for each hisser.

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Wouldn't inbreeding cause homogenization like in all of our dog breeds?

Well, in a broad sense inbreeding does reduce variation in a population and can lead to fixed alleles since inbreeding decreases the average heterozygosity in a population. SO, everybody is the same (or for a polymorphism, VERY distinct) which causes problems when you start combining deleterious recessives. I'm trying to play around with alternative mating strategies and the presence of these two phenotypes in my culture. Really I just wanted to see if the patterns I’m seeing in my culture have been noticed by others, which seems to be the case more often than not. I have a neat undergrad research project going on that I hope to let you all know about when it’s completed.

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Well, in a broad sense inbreeding does reduce variation in a population and can lead to fixed alleles since inbreeding decreases the average heterozygosity in a population. SO, everybody is the same (or for a polymorphism, VERY distinct) which causes problems when you start combining deleterious recessives. I'm trying to play around with alternative mating strategies and the presence of these two phenotypes in my culture. Really I just wanted to see if the patterns I’m seeing in my culture have been noticed by others, which seems to be the case more often than not. I have a neat undergrad research project going on that I hope to let you all know about when it’s completed.

We should talk. I have several thousand right now that are all descended from an original 3 that I aquired as adults in 1992. They have been completely isolated with no new additions since then. They have been my only roach species until just recently. There is a tremendous variety in my colony. I'm trying to post pics, but having some trouble. If any of this would be of interest to your project, I'd be glad to help.

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It seems to me that there are two distinct body types that exist in G. portentosa. There are thinner, laterally, and longer individuals and then thicker, shorter individuals. I’ve noticed it in males and females. It’s harder to see in females since they become so distended with young as they approach birth but even in taking that into account, I can see it (maybe). Would anybody agree or disagree with this hypothesis?

I took 180 pics and only a few turned out. I'm working on building a roach photo studio. Here's a couple that turned out decent and illustrate the point:

This is the long, cigar shaped type.

post-934-1261604834_thumb.jpg

What you can't see in the photo is how flat the male is and how round the female is in profile. She's twice as thick as him.

post-934-1261605230_thumb.jpg

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It seems to me that there are two distinct body types that exist in G. portentosa. There are thinner, laterally, and longer individuals and then thicker, shorter individuals. I’ve noticed it in males and females. It’s harder to see in females since they become so distended with young as they approach birth but even in taking that into account, I can see it (maybe). Would anybody agree or disagree with this hypothesis?

A couple more nymph pics.

Cigar shaped...

post-934-1261605667_thumb.jpg

Flat and wide...

post-934-1261605714_thumb.jpg

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Varies with the amount of food they've eaten recently. Notice how the one who's flat-shaped has molted recently.

That is true, but the phenomenon still appears with adults who are a long time past their last molt.

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Varies with the amount of food they've eaten recently. Notice how the one who's flat-shaped has molted recently.

What makes you think he molted recently? Remember, even though I've managed to keep them alive for a while, I'm still new to the "hobby". There are bunches of those wide, flat shaped ones. I don't think it has anything to do with how much they've eaten. Some of them are just built like that and when I've housed them individually for months on end, neither type changes shape when they are well fed or cut back. I took a lot more pics to illustrate my point, but almost all of them came out blurry or dark. I'm setting up a better lighting and bounce system, so I'll post some more asap. Some of the little bitty ones are as round and flat as that dime and others look like the one in the pic.

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They always get that shape after molting, and that guy is also very light colored, a possible sign of recent molting.

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  • 2 weeks later...
They always get that shape after molting, and that guy is also very light colored, a possible sign of recent molting.

Looking at size genetics in G. Portentosa currently, I have noticed the difference you have talked about and it is NOT related to how much they have eaten. I have no conclusion as of yet as to why u see these two forms. There are those "in the middle" though in my colony, do you have those "average" ones as well or is there a gap between the two types?

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Looking at size genetics in G. Portentosa currently, I have noticed the difference you have talked about and it is NOT related to how much they have eaten. I have no conclusion as of yet as to why u see these two forms. There are those "in the middle" though in my colony, do you have those "average" ones as well or is there a gap between the two types?

Those are the two extremes in my colony, but I have everything in between too. Most of mine are the normal or average looking type. I've also got some of those jet black ones and they run the full spectrum of sizes and shapes.

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