The Insect Paradox

It seems that no one has ever had anything to do with maggots...

It seems to me that the matter is in the very high quantitative density of insects, in addition to excluding food competition, larvae are also more dense filling of various food niches.
That is, insects with a relatively simple device and small size developed quantitatively, and they needed the larval stage, and mammals, among other things, with a rather complex device and large size, might simply not be able to tolerate histolysis without much damage. At least the problem is in shelters, where to get so many of them. And even if incomplete metamorphosis, then all the same - molt, and incomplete metamorphosis is often a type of nutrition similar to an adult, it is almost like direct development...

"insects with a relatively simple device "
Can not agree with the statement: remember what they have in this device. In addition, the question was not about mammals, but about large vertebrates in general. In addition, the loss of larval stages at landfall is a fairly common phenomenon, for example, among snails. Also, if we are talking about "simplicity of structure" (I hate such a phrase, since I have NEVER met any scientific description of it ANYWHERE), then millipedes and cryptojawed insects should have a "simpler structure", but nevertheless they do not have metamorphosis in the form that they do not have in real insects. And histolysis of pupae is a progressive phenomenon in the evolution of Insects. Hiding places were a problem, but something like rodents and lizards could find them without too much trouble. In addition, many mammals have such a thing as hibernation, and here you can not do without shelter. Yes, and you and I will stretch out our legs without shelter: first it was caves, now it's houses.
As for more dense filling of niches, I agree.

I speak of "simplicity" based on the structure of an insect's face, and the structure of any vertebrate animal. The meaning of the larva is that it has a very different structure from the adult stage, which allows it to live and feed in other conditions, and often this device is relatively simplified, that is, many organs are in their infancy or simply do not exist. And for their appearance, a radical restructuring of the body is needed. And the bigger the animal, the more difficult it is. In addition, most vertebrates, and almost all of them, are quite "energy-intensive", they need large reserves of nutrients, how to accumulate them? That's what I meant.

All sorts of snails, spiders, millipedes, note that their young feed on the same things as adults, why do they need larvae? And why this is so, that's another question, maybe they didn't just have time, everything was already occupied, or vice versa, there is a lot of food, why divide in this sense. Do you know examples of food competition in snails and examples of lack of food for them, based on what they mainly eat?

And by the way, why don't you tell us your point of view on the question you put?

2 sealor: But what about insects that have incomplete transformation, usually their larvae occupy the same ecological niche, feed on the same food, and they are arranged almost "imagically". And with complete metamorphosis, the larva is often arranged in a different way than in a simplified way, there are no organs, or they are in a rudimentary state, but there are dispensary organs, and they are not very simple.
2 Chromocenter: I agree with Sealor, please state your point of view

Sergeich

About how to deal with such insects, I do not know what to say, well, these are already "not the same" insects, it's all the same as millipedes, spiders, etc. And by the way, this type of metamorphosis among eroptera, and they also have a weak intraspecific age-related food competition, there is usually plenty of food. But diptera, here it is already different, food differences are very sharp, and the food of larvae is usually quite limited.

As for simplicity, you also make it sound like I'm talking about simplicity in general. I mean, insect larvae are "born for metamorphosis", they have everything for this, easily changeable fabrics, special skill material.
Imagine a vertebrate larva with a complete transformation. Just do not imagine any lampreys, but the larva of a dog, for example. And what, what should such a larva look like, where is its ecological and food niche, and what will the restructuring of tissues look like, how long will it last???

In itself, the existence of larvae is not a primary phenomenon in the evolution of multicellular organisms, but developed in order to reduce competition between adult and larval forms by separating them ecologically. This phenomenon can be observed, for example, in amphibians. However, during the development of fresh water and land, larval stages began to be lost, as can be seen due to the fact that in these environments more activity is needed (to resist the flow in fresh water, which is impossible for many larvae, since they are planktonic, or to resist drying out on land, which is also not so easy). I agree, often the larvae have a simpler structure, which is understandable, since they still have to develop, and the larva is often like an emyrion that has left the egg, because it is very small. However, since the larva must also live, its path of development under the pressure of the conditions in which it lives is distorted, that is, if natural selection does not act randomly on the larvae, then their path of development will deviate from the straight line and they will develop those characteristics that they need for survival. If this process is continued, it is possible, on the one hand, to abandon the adult form altogether, and on the other - to get a complete dissimilarity of larvae and adult forms. Then it is assumed that the organism has two stages of development: one leading to the larva (embryo), and the other leading from the larva to the adult form (pupa or something like that). By the way, as far as I know, nemertine larvae also do not look like adults. From this it follows that insects with complete transformation did not descend from someone like erect-winged insects, which have essentially no larvae, but from someone like dragonflies or mayflies, whose larvae have little resemblance to adults. As for other arthropods, they lost larvae, that is, they shifted organegenesis to relatively early stages of development, thereby obtaining reduced adult forms, due to the inability to "adapt" larvae to life in land conditions. But why the cephalopods did the same is anyone's guess.
By the way, the restructuring of tissues also takes place in our country: after all, the needles disappear and the gill slits disappear.

And what will the epitheliochorial placenta look like in a May beetle?
But seriously, dragonfly naiads are most likely second-water, since even under water they breathe air that is released by the gills near the trachea. Why would they go into the water, because they do not fly, adults of their own species do not compete, and interspecific competition both on land and in water among predators is very high. At the same time, the larva is still close to insects with Hemimetabola. And it is quite similar to the imago. It seems to me that the evolution of vertebrates and insects did not follow opposite paths, but in different planes. and it is difficult to compare them, as warm and soft, but you see, in 300 years the dogs will come up with some thread larva or pupa.
By the way, not quite in the topic, but I wonder why some people decided on the inner skeleton, and others on the outer one?

"By the way, not quite in the subject, but I wonder why some people decided on the inner skeleton, and others on the outer one? "

I think, again, it's all about size. Imagine, in a small insect and so little space, and if there is also a skeletal support.. Yes, and small organisms to preserve moisture in relatively dry conditions, it is better to have a solid outer cover.
Insects were supposed to be small initially, so they have such a skeleton.

Most likely, of course, the larvae of dragonflies are secondary, probably all insects that are in the water are secondary, and almost all of them are predatory, herbivorous something and I don't know, there are larvae of diptera, but those in my opinion feed on rotting remains, or protozoa. So what, someone had to climb into the water, in the end, occupy a niche, here are dragonflies along with all sorts of other mayflies, and in the water Water Lovers / floaters out completely in the water, and imagos and larvae, and all predators, and live the same.

"Water lovers / swimmers are completely and completely in the water, and imagos and larvae, and all predators, and live the same."
By the way, both among Colorado potato beetles and ladybirds, larvae do not differ much from adults in their lifestyle. But these are clearly secondary phenomena, and such a convergence of the lifestyle of larvae and adults appeared already when their morphological division went too far and it was no longer possible to reverse it. The larvae of mayflies and dragonflies are, of course, second-water, but apparently their close ancestors lived in very wet biotopes, so their transition to life in water was not unexpected.: they simply couldn't move on to life on land, as they apparently couldn't cope with the problem of drying out, and ended up in the water.
"And what will the epitheliochorial placenta look like in a May beetle?"
It is difficult to imagine nemono, but not because they are difficult to connect: the egg of an insect can theoretically easily receive food from the maternal oragnism during development, since insects have extra-embryonic shells, but water is bad: after all, insects are the only animals that completely and at all stages of their development came out of it.

Yes, I forgot about the skeleton: in Vertebrates, it is internal because initially they were too soft, and they were soft because they were filtrators, but when they began to gain activity, the connective tissue began to "clump" so that the muscles had something to rely on, forming first cartilage, and then bones (modern boneless vertebrates are a secondary phenomenon). All this happened in an aquatic environment, and as can be seen, skin respiration continued to be of great importance, so the epithelium did not become compacted to the skeleton. In Insects, the external skeleton has deep traditions, especially when you consider that Nematodes that also have cuticles belong to the same group as Arthropods. In addition, if you are small (although looking at some eurypterids you will not say this, but we will assume that this is an exception), then the mechanical strength of muscle fibers may already be enough to support the body, so you can not particularly care about the skeleton, and develop it only when you get out on land, where there is no solid opaory absolutely nowhere.

The larvae of many caddisflies, freckles, mayflies and diptera - not predators, but water-lovers only in the larval stage-fly, then they eat grass. By the way, there is an old book, Mamaev B. M., Determinant of insects by larvae, 1972, I can scan if colleagues are interested, I don't promise quickly, in a couple of weeks.

Yes, I forgot about the skeleton: in Vertebrates, it is internal because initially they were too soft, and they were soft because they were filtrators, but when they began to gain activity, the connective tissue began to "clump" so that the muscles had something to rely on, forming first cartilage, and then bones.

By the way, there is a theory that vertebrate bone originally appeared as a dielectric, insulator.

IMHO, there is one more point - in general, the insignificant duration of the insect (despite all sorts of 17-year-old cicadas) and a large proportion of r-strategists (perhaps the r-strategy was primary for terrestrial arthropods, although this can be debated, and for insects with complete transformation it is, IMHO, almost for sure). And since the value of an individual's life is low and life is short, it is possible to divide the function of biomass recruitment and the function of reproduction between different phases, while maximizing their efficiency. Look at the coccid: the female is valuable for a longer period of time - and there is almost no metamorphosis, the male is needed only for a short time - and his metamorphosis becomes surprisingly similar to complete. Insects that have a similar ecology of imago and larvae are characterized by a long life of imago, while those that have a very different ecology are full of aphage imagos.

This post was edited by PVOzerski - 06.03.2006 11: 12

By the way, there is a theory according to which bone in vertebrates appeared initially as a dielectric, an insulator.

You can say a few words about this theory, or links, I wonder.

"water lovers are only in the larval stage-they are hungry, then they eat grass."
Well, I don't know, I have just Hydros aterrimus lives-the moth eats even as

I'm also interested in insulator bones, how is that?

PVOzerski
Well, yes, this is the answer to the question of the topic. Larvae are basically a good way to accumulate biomass, but due to the variety of pathways, it's all presented differently. In some larvae, this is generally "just a worm", and the larvae of others can multiply, have a complex structure. Vertebrates, and mammals too, go through a "larval-like" stage in embryonic development, but this all happens quickly and within the egg or the mother's body. And it is difficult to imagine how such larvae would have been if ontognesis had stopped and they were released, then "molted" on an adult animal...

"And it's hard to imagine how such larvae would have been if ontogenesis had stopped and they were released, then "molted" on an adult animal... "
In my opinion, this is just a matter of habit: if we behaved in this way, then our modern development would seem strange.
"And since the value of an individual's life is low and life is short, it is possible to divide the function of biomass recruitment and reproduction between different phases, while maximizing their efficiency."
To be honest, I don't really see the connection between these things. In addition, imago-aphages are most likely the result of excessive fascination with larvae, and then ants live for a long time, but this, in general, is a very special case. On the other hand, there are aphids - they also have no metamorphosis, and the value of an individual is negligible.

IMHO, the relationship between short life expectancy and phase specialization is quite direct. Imago-aphagus-often almost a gonad with adaptations for settlement, nothing or almost nothing superfluous. As for aphids, do not forget that they are viviparous, so this is a manifestation of some kind of care for the offspring, that is, not an r-strategy in its classic form, although it is close.

"IMHO, there is a link between short life expectancy and phase specialization"
That is, the shorter and longer the phase, the more specialized it is? I agree.

Indeed, in the face of the metamorphosis of insects, nature presents us with an interesting riddle: almost all land animals do not have it or almost do not (an extra pair of legs in ticks does not count), even if their aquatic ancestors and modern relatives have it. In insects, on the contrary, metamorphosis developed a second time and showed a tendency to deepen. Obviously, to solve this riddle, you must first remember what unique morphophysiological features insects have. It seems that the key role is played by the combination of the external skeleton with wings, which is not present in any other class of animals. The external skeleton, as well as the type of arthropod itself, imposes one significant restriction: you can grow only by molting. With wings, you can't shed them. At the dawn of evolution, they probably tried it, but it turned out badly: look at the mayfly, only the lazy will not catch their subimago. The others "decided" that it was better without it. And now it is necessary to grow wings and ales, the train does not go further, there will be no more lines. It's not good to reproduce without wings - you'll overpopulate the biortop. So we have a division into an adult winged imago that does not grow, but lives a sexual life, and a larva preceding it, which, in general, is the same, but without developed wings and genitals. The larva eats and grows, the adult disperses and reproduces. The division of rations came later. And even later, the larva realized that the fewer molts, the more likely it is to survive, and it is possible to grow between them due to stretching, but for the efficiency of the process, it is better to simplify the structure. But here there was a strong morphological gap with the imago, which could not be filled without the pupa with its histolysis-histognesis. And then both the imago and the larva had their hands free to develop in any direction independently of each other. Adults of most groups have followed the path of further specialization in dispersal and reproduction, while larvae have followed the path of morphophysiological regression, which facilitates nutrition and growth. And already at the very end, some of the adults decided to give up the wings, but the law is not retroactive. That's the way I think.

Legs, arms, wings.. the main thing is the tail!!
All these expert arguments are illogical, to put it mildly. For example, the chapcherry, being a vertebrate animal and having a shell, does not shed and even more so does not engage in complete transformation, the same goes for birds and bats, they have wings, but they also do not suffer from complete transformation.

Everything seems to be much simpler, metamorphosis, especially with complete transformation, is peculiar to organisms that lay very small eggs or worms, with large own sizes, and correspondingly if present. large complex-functional appendages, which purely from "quantum" regularities cannot be repeated, or with difficulty, during the hatching of very small individuals.
All such organisms have a similar metamorphosis - fish, frogs of all kinds, even kangaroos In the same birds are already on the verge of incomplete transformation.
General patterns should be deduced, not arms, legs, wings, tail

And in general, eh, that was the time on molbiol, 2002 2008-the best ...

And so Pan decided to keep his original nickname in it

In spiders, the development is not very direct, but through at least one nymph, when the functionality of their structures is not complete, and even after the 0th molt, spiders usually do not feed but only after the first one, although our theorist understands why this does not know, it is clear that no species of tarantulas has ever bred))
In earthworms, too, the testicles are not very large, but nevertheless you need to read more carefully

I wonder how, and most importantly where, if they are full of food reserves from birth, the nymphs of bird eaters eat? I have never seen this in my own people, nor have I ever seen any specific descriptions of it on the forms, only rumors and facts like the sitting of one nymph on another. And this is despite the fact that even spiders 1 molt, which in principle are already quite "finished", do not want to eat, and so by the way, and araneomorphic spiders too.

Examples-yes, all amphibians, their adult forms are quite terrestrial.
Ticks have an exoskeleton but no wings, but according to science, they have metamorphoses.
By the way, my theory is quite suitable for wings, which can be considered appendages of a complex shape, but to assume that it is the appearance of wings that causes the appearance and consolidation of metamorphosis(in this order) in insects, this somehow sounds too flimsy, to put it mildly
To do this, you need to give examples from the geological record, where all these processes would be reflected-first the rudiments of wings, then metamorphoses.
Metamorphosis itself is a very beneficial phenomenon that gives more options for development, and it is quite possible that the wings themselves are a consequence of metamorphosis, the wings appeared thanks to it, and not vice versa.

Probably, there is where else to eat, in addition to stocks. They're not packed to the brim, so just a little more and - burst. At least I clearly observed one nymph thrusting chelicerae into the abdomen of another, by the way, the children of nanda yours.

Well, a bad case, like all the others involving cockroaches that live in Panov's head.

Let's go from the other side: what is the metamorphosis of insects and what was it, according to Pan, in their wingless ancestors?

The latter is generally a waste of some kind, as the presence of "significantly developed" wings can prove the appearance of metamorphosis in the ancestors of insects precisely after the appearance of this aromorphosis, that is, wings-it's difficult for me to understand)))

As for the first one, my idea differs little from the encyclopedic one, so that metamorphosis, including in insects, is "a deep transformation of the structure of the organism, in the process of which the larva turns into an adult" (c)
"In the life of animals developing with metamorphosis, there is at least one larval stage, in which
the organism significantly different from an adult animal"(c)
Of course, these definitions are not perfect, for example, a person has many larval stages, but they simply develop in the womb, and correspondingly. they are not free-living.
Well, the "depth" also needs to be determined, maybe for me the transformation of spider nymphs is already deep)))

So, I do not see any reason for metamorphosis, even if it is secondary, to arise in the wingless ancestors of insects simply as a useful adaptation, and wings-as a consequence of the metamorphosis itself. To understand this, you need to think a little, and it is advisable not to scratch the turnip

So, I don't see any reason to prevent metamorphosis, even if only for a second time , from appearing in the wingless ancestors of insects simply as a useful adaptation, and wings - as a consequence of the metamorphosis itself.

In general, I read here about metamorphosis, and not really surprised ))
Early forms of metamorphosis, according to modern concepts, appeared long before the appearance of wings, these are protomorphoses, which still occur in mastoid insects.
Moreover, this type of metamorphosis involves a change in metamericity, and not just the growth or appearance of some appendages, which are wings.

In addition, there are different views on the origin of the complete transformation, not all scientists are of the opinion that it arose from an incomplete transformation, it could have arisen in protomorphic ancestors bypassing the incomplete transformation.
Moreover, no one, except our okodemik, of course, can postulate the exact course of insect evolution, since other people did not hold a candle during these processes. Just because a complete transformation came from an incomplete one does not mean that the incomplete transformation did not arise as a reduction of the complete one.

But okodemika's statement that insects were not worm-like at the dawn of their formation is actually some new trends, the primary insects according to modern ideas just had a worm - like body, developed metameria, and a minimum of appendages.
Therefore, a metamorphosis with a worm-like protolichine that changes in one way or another during its molts may well be.


The fact that the biogenetic law has long been unsupported in scientific circles, I learned in general at the beginning of 2000 on the same forum, when there were no thieves nedokodemikov ))) If in bursas they teach even from textbooks of Pre-Nobel times, then we can only sympathize)
Simple cramming of letters in books is useful only for circus shows in the style of "reading War and Peace by heart letter by letter", but in order to create something new, whether it's a hypothesis, a net, or an object, you need to be able to combine facts and material to get relevant novelty with what, however, all nerds, and thug okodemikov always have problems
Therefore, in the countries of Western civilization, there is always progress, they do not chew the same gum from "traditional generally accepted knowledge" for 300 years

Well, about false attacks in the style of "kicked out of the biofac" - this rather perfectly shows the level of the" spiritual " state of this individual, and this level is visible in all such discussions ))
Pettiness, deceit, envy and malice-that's all that such people can offer the world