Reptile & Amphibian Forums

I've searched around and am having a hard time finding definitions of terms that have been used on the forum regarding egg development. So for the neophytes here (present company included), can you define the terms diapose, diapause, diapase, etc, etc....Thanks much for your help my friends

First please try to understand there are two basic points of view with this. One is from a purely scientific view. The other is from a purely practiced point of view. These often do not matchup.

That is, the reproduction biology of varanids is very weak in both the lab and the field, therefore, very weak in literature. There are very few studys done on this.

On the otherhand, there are now thousands of reproductive events for varanids in captivity, mostly in private hands.

Why I am explaining this is simple, there are terms and there is practice. In practice, the terms are not so important, the results are. In literature, the terms are very important, as there are no results. So whether its diapause or diapase, its not important, in practice, monitor eggs have pauses in development. Call it or spell it anyway you want.

Most of the science behind varanid eggs is based on chickens and not varanids. So, the actual biology is often mis-represented. Its also based on field work, which again is often not accurate. I know, "whatca mean willis". Just for instance, science often based reproductive condition on seasons. For instance, they would check the development of overies and gonads thru out different seasons and used this to base many assumptions on. In captivity, we see something totally different, we see reproductive females have developed overies and males developed gonads year a round. Even if hibernated.(same for males)

How the above is understood is different between the two fields. I believe underdeveloped sexual organs are with individuals that are not part of the breeding population. Not a product of the seasons. Productive females contain developed overies containing many sets of ovum, year-a-round. I have found this in both nature and in captivity. How this came about is also simple, science checked different females at different times, captivity checks the same females at different times.

What all the above means is, neither field science or captivity is an exact science, so the terms used now are also not exact.

I would love to tell you this is all well understood and we "pros" have it documented in exact detail, but I would be lying, its not like that, its more of an art then a science.

Its not about measuring hormome levels and when they reach certain levels, introduce a male, or again measuring different levels and putting in a nest, and recieving eggs in ten minutes. Its "all" about gut feelings and past experience.

Maybe one day it will be a science, but then it would be no fun. Cheers FR

I finally got those freaking croc monitor images out of my mind.

I know, I know, they are like squirrels over there, it's really hard for me to grasp that, I still get gut wrenched from Gopher and kingsnakes D.O.R. here.

What a pretty animal it was....

--Robert

I can get my arguses to sit still for me, too!

Hahahahaha!

Luke (who, if he knew anything about egg development would be up to his ears in monitors by now)

The term is 'diapause', and it refers to any situation where an embryo begins to develop, then enters an essentially vegetative state for a period before resuming growth and differentiation. Usually in reptiles a diapause occurs immediately after the eggs are laid. It is thought to be a mechanism allowing females to deposit eggs at the end of the best season for foraging, while the eggs hatch some time considerably later when resources for juveniles are at a peak. In practical terms, an Australian monitor thus might lay eggs at the end of the wet season (April) but the eggs do not hatch until the beginning of the following wet season (December).

The incubation period for monitor eggs varies from 180-300 days (exceptionally, over a year). This is far longer than would be expected from the sizes of these eggs – even crocodile eggs hatch in 70-80 days – and thus we conclude that there is a diapause involved. Another indication of this is the wide range of variation in incubation times seen between clutches, or sometimes within a single clutch even when all eggs were apparently treated in exactly the same manner.

There are two basic ways that a diapause can be induced. Many reptile eggs have the ability to enter an externally-influenced 'false' diapause if conditions in the nest require it. For example, eggs of some reptiles can suspend development if the nest is flooded, or when temperatures fall below some critical value. A 'real' diapause is something that is intrinsic to the egg, rather than imposed on it by external conditions. What the controlling influence might be is not known with certainty, but one suggestion is that the female (or even the embryo) creates proteins that block development until they are somehow broken down. This could be a simple 'clock' mechanism (it just takes 100 days for that protein to break down), or there could be some environmental change (that dependably occurs sometime after the eggs are laid) that triggers the breakdown.

One of the big difficulties in breeding monitors in captivity is that the eggs take so stinking long to hatch – every day brings another chance for something to go wrong – and it surely would be useful to understand what controls the diapause they undergo. There are a few records of monitor clutches hatching in about 70-80 days (and also a few weird ones where diapause was greatly extended). What we don't know is whether the females that produced those clutches failed to produce enough of the arresting factor (or too much), vs. whether some unique external event in the incubation process either triggered or failed to trigger the end of diapause. If it is the former, we are probably stuck with these long incubation times. If the latter, there would be an opportunity to work out an incubation treatment that would eliminate diapause, and you'd all have your hatchings 4-6 months sooner.

Posts such as Frank's here simply confuse the issues. We do know that there usually (but not always) is an arrest period (= a diapause) in the development of monitor eggs. The people who are best-placed to help us understand what actually occurs and why are the large-scale successful breeders, simply because the science-types don't have access to large numbers of monitor eggs (or aren't interested enough in the question to pursue it). At the same time, attitudes such as Frank so often expresses guarantee that hell will freeze over before anyone who has the curiosity and technical skills to address the biology of the matter can actually interact productively with people who have the practical experience but dismiss the relevance of a scientific approach to the question.

I agree with most of what sam says here, and its shows exactly what I mentioned in my original followup to you.

What causes them to diapause in nature is one thing, and surely they are guessing, and I believe they are guessing very well.

What happens in captivity, is another thing altogether, as we do not have the same impulses. You must understand, we have to deal with what happens in captivity, not what happens in nature. These may or may not be different. Again, its not about right or wrong, it simply is what it is.

What sam fails to understand is, its about different experiences and different conditions.

Of course I do not agree with sams last paragraph, sam said;
Posts such as Frank's here simply confuse the issues. We do know that there usually (but not always) is an arrest period (= a diapause) in the development of monitor eggs. The people who are best-placed to help us understand what actually occurs and why are the large-scale successful breeders, simply because the science-types don't have access to large numbers of monitor eggs (or aren't interested enough in the question to pursue it). At the same time, attitudes such as Frank so often expresses guarantee that hell will freeze over before anyone who has the curiosity and technical skills to address the biology of the matter can actually interact productively with people who have the practical experience but dismiss the relevance of a scientific approach to the question.

He again is promoting social differences within the monitor keeping comunity. In reality, monitors are monitors, there abilities are static, we cannot change them in captivity, we can only allow them to express different parts of their abilities. its all is one package, whether he likes it or not.

For instance, monitor eggs can diapause, pre-development and post-development. We know this, because its easy to test. Candling shows degree of develpment. Also, developed eggs(after pigment development) darken up to the appearance. Its easy to see. But you have to have the eggs to see it.

Good luck in your search and I would recomend you giving a clearer picture of what your interested in. Thanks FR

Hi Sam,

Dr. Mamadou Cisse discussed this very feature in wild V. exanthematicus and V. niloticus 25 years ago; she discovered that a rise in lipid and carbohydrates corresponds to the same period these two varanus engage in courtship/mating/ova production in West Africa's Senegal: a correlation and connection? I am not sure, but it may be the trigger mechanism you spoke of, in association with climate/environmental factors which also have alot to do with successful annual reproduction.

Unlike the more primitive African Varanus which have only 1 breeding summer, during the African summer which have enormous clutches (50-70 eggs is known!)- the Indoensia species have 3-4-5 clutches annual, with small clutches (usually >12), perhaps the diapause is more influenced by nutrition of the females and their environmental factors, as they are pregnant almost around the calendar clock...

There are a few captive breeding incidents that raise the eye-brows, such as a 90 day incubation period for V. prasinus back in the 1970's...thought to be to-date a hoax, but maybe this is evidence of your post? I tried to track the fellow down and inquire further but no luck there...

Sources:

Cisse, M. 1971. La Diapause chez les Varanides du Senegal. Notes Africaines 131:57-67.

Cisse, M. 1975. Le cycle annuel glucido-lipidique chez un Varan du Senegal. Comptes Rendus Societe de Biologie 169(4):1084-89.

Cheers Sam,
markb

I believe that protein levels in yolk to be the cause of diapauses, in times of plenty when females gorges on high protein foods the eggs produced have bigger yolks with a higher protein density, when the embryo absorb this high protein yolk its growth is rapid, to fast for the rest of the egg to follow, the embryo is therefore constricted, as he cant produce more waste and he cant absorb more yolk his only defence is to expel water thru the shell, if humidity is high, then this is impossible for the embryo, all development must be haltered until water can be lost relieving pressure to allow growth to continue.
Captive observations worth noting;
Food variety and what they are fed before being offered to your monitors, humidity and temperatures at nest site (I believe female will deliberately choose lower temps with lower humidity for high protein eggs) also eggs that shows a rapid growth followed by water lose should be kept in a 50-60% humidity range and temps lowered (why several egg containers must be ready). Thru the years iv tried to understand the needs of nesting monitors, at first I tot it was quit simple a perfect temp and humidity but it doesn’t work this way at all, its always variable and females can nest in many different ways temp and humidity, however a steady and reliable husbandry will make for a steady nesting pattern.
And this is where aim at, working with diets to reduce incubation time.

For those of you who hatched eggs of the same species and experienced a huge difference in incubation time from one clutch to the next, perhaps a lower protein diet combined with your best proven temps humidity is the answer.

Rgds

To add to my post, I remember some time ago in a Vivarium interview about monitors, the interviewer was shocked when Frank said that he didn’t gut load his crickets, as I believe he (interviewer) at the time just printed his research on the subject and had a very opposing view then Frank. All this to say that minerals, given in quantity may be more significant then protein in egg development, especially in captives where energy expanse is very limited.

Just when you thought it was safe to go back in the water…. I did some searching for literature on embryonic diapause in reptiles, and found one paper that is very relevant to this discussion about incubation times in monitors. The citation is: Birchard, G.F. et al., 1995. Oxygen uptake by Komodo dragon eggs: the energetics of prolonged development in a reptile. Physiological Zoology 68(4): 622-633. Birchard et al. argue that embryonic diapause does *not* occur in monitors, based on continuously increasing oxygen uptake by developing eggs. If a diapause occurred, one would expect that oxygen consumption would level off or decrease for that period, and start to increase again once the diapause stage had passed. The authors also candled eggs throughout development and report that embryonic growth was *not* interrupted, as a diapause stage would require.

So, those of us who have concluded that monitors have embryonic diapause (as seen, for example, in turtles) are wrong based on the Birchard et al. results. Instead, embryonic development in monitors is continuous, but slow. Komodo dragon eggs require over twice as long (210%) to hatch as do eggs of the same weight produced by other reptiles (such as pythons and crocodilians). Birchard et al. present a figure comparing incubation times vs. egg weights for 10 species of monitors and 20 other reptiles that shows that monitor eggs of any size take about twice as long to hatch as do "average" reptile eggs of that size. As would be expected from this, the oxygen consumption rate of monitor eggs is about half that of other reptiles; however, the overall energetic cost of development is higher than predicted, presumably because more energy is used for "maintenance" (vs. actual growth) during the lengthy incubation period.

Thus, we are barking up the wrong tree to refer to diapause or arrested development in monitor eggs; instead, we should be asking why they develop continuously, but at about half the rate that is usual for reptiles.

or lack of a problem. Diapause or slow development is not a problem that needs to be fixed.

Here you bring up diapause, you get comments, then one person reads "another paper" and changes his view altogether. Thats the problem about literature. Do you believe the animal or the paper?

The nice thing about keeping and working with monitors is, I do not have to believe any paper or person. I only have to believe the monitors. The goal of me keeping monitors is my new favorite word, simple. I want to see life events and may I add, progress. If any of that matches wild monitors or what people think of wild monitors, then great. But if it does not, thats great too. As long as we are progressing.

Whether researchers agree or not, their comformation is not my concern, not in the least. From a basic point of view, most people are concerned about keeping a monitor alive, or having it feed normally. With that in mind, why should I be concerned why an egg diapauses or how it does. I am not concerned.

Heres why. If they diapause or diaslow(slow development) it does not matter to me(as long as they hatch) If they do so, to time the hatchlings with a rainy season, does not matter to me, we do not have a rainy season to be timed for. With some specie of tortoise, they blame diapause for some egg failure. We have not seen that problem, some hatch quicker then others, so what.

Its surely of interest that they may or may not, hatch for a reason of hatchling survival, or whether they diapause or slow develop, but its not of concern in captivity.

Reddragon, your question was about defining some of these terms, now you know why we make up our own. The rest of the world cannot agree with eachother.

I feel sam thinks he is the defining factor in what I should say/think, but of course, I do not agree with him. I will say what I want to say. I say them for reasons gained from the montiors themselves. So far, I've done very well. The right or wrong is not in the terms I use, but instead in the results I get. And yes, those results have them scratching their collective heads. For that, I am glad, I hope they figure it out one day.

My simple outlook is, call me anything you want, just call me to dinner. Well, you can call any of this anything you want, but I am eating dinner all the time. Thanks and I hope this helps.

Please do laugh at the picture, it was me as a kid in the sixites. FR

Thanks for all of your input on this post. For the record, I was not looking for the definitions in order to explain the stages in which monitor eggs develop specifically, all I was looking for was to expand my knowledge of the subject by defining what the terms actually meant. Whether these stages actually occur in monitor eggs wasn't really the question, although the effect of the post was exactly what I was looking for. One of the most enjoyable aspects of this forum for me is intelligent, informed, and experienced opinions being discussed. Believe me, I do not subscrive that scientific study always defines how things work in the real world, but I do believe that it's good to learn as much as you can about the subject of interest and then decide through your own experiences if the scientists were full of bull-pucky.

Oh, and nice pic Frank......sixties huh? Yer giving away your age amigo.

As usual, the content level in your responses here is mighty low, Frank -- pictures that are irrelevant to the topic, mumbo-jumbo, etc. In your post above you claimed to have seen every kind of diapause there is.

I am not convinced that the work I described above provides the last word, but it's the best word at present.

The pic is simply something to laugh at.

About content, wheres yours?????? no, not others, yours?????

Please consider this, forums are for talking to people about their experiences, they are not a publication. We surely do not have to be right or for you to agree with us/me. We all know how to look up papers and hopefully we all will read as many books as we can. Again, its more like conversation around a dinner table. I believe its more about eachothers own unique opinions and observations. Its not about absolute science or whatever the heck you think it is.

I know its confusing to you because its written, but it really is conversation. Thanks for understanding. FR

Hahahaha! Please excuse me, but I have NEVER experinced the kind of insulting, beligerant, accusatory, "holier than thou" type of conversation that is so common here, at ANY dinner table in my entire life! Thank goodness.

I am sorry, but please understand, if I am questioned in a attacking manner, I feel I have the right to attack back. If people are nice, then I am nice. I really do not see why I am suppose to be nice to bungholes. (tell me why I should)

I do not expect anyone to believe anything i say. But really all THEY have to do is say, thanks FR and not ask anything else of me(the polite thing to do) You have to ask them, why do they attack me for things they/we do not understand(its not about right or wrong, is it?).

You should understand, whether I am interpeting my monitors actions and results correctly or not, is not that important. That I have stuff to interpit is that important. You see, its about the stuff.

If its about that turn the cheek thing, I ran out of "other cheeks" long long ago.

Also, I kinda have this odd feeling that we should not cultivate keepers that are offended by the least little thing. The reason is, this is not a "nice" hobby. Horrible things can and do happen. TO ALL OF US. Maybe a little thick skin is not so bad.

This is not really an excuse but, I was in sports much of my youth, and well, that was all about offense. Then as an adult, I worked construction and owned my own company, again, it seems all constrution folks to on jobs is offend eachother. It sorta helps past the time, when you not really doing what you want to be doing(playing with reptiles)

Here, people are offended by nothing.(fr does not like me, wa wa) see, that was very offensive, but really why would anyone care if I like them or not?(specially when its only words on a screen) Cheers FR

The pic shows someone who has been working with reptiles for 30-40 years and is one of the most proficient reptile breeders around. In order to do that he has seen lots of eggs, nests, gravid females, etc.

You on the other hand change your mind in an hour based on one paper that you didn't even write.

Let's see, who to listen too.....who to listen too.......

np

I have some very basics on eggs and formation etc..