Caterpillar Sex

Cecil's Columns/Staff Reports
21

I’ll take the easier question first, which is that of exegisis. Yes, like many parthenogenetic species, aphids do sometimes have sex. This may occur through a sort of “alternation of generations,” in which one sexual generation is suceeded by several parthenogenetic ones which are then suceeded by another sexual one. Basically parthenogenesis is good for rapid increase in a stable environment. You can increase rapidly because you don’t have to waste time or energy on such frivolous things as courtship, sex or males. However, sexual reproduction, because it allows genes to recombine in different arrays, is better for coping with a changing environment. With aphids, there are additional complications in that there are both winged and wingless forms. The winged forms colonize new host plants, and they are induced by crowding. Sexual generations, in the temperate zone at least, seem to be induced by changes in day length; when the days get shorter sexual forms are produced, and these lay the eggs that overwinter. The gall midges I mentioned in Cecil’s article are similar; the paedomorphic parthenogenetic forms occur principally when they are colonizing almost unlimited food sources like fungus beds. Once crowding occurs or food becomes short they produce true winged sexual adults, which can disperse and colonize new food sources.

And yes, parthenogenetic aphids are often born pregnant. So a mommy aphid may actually be pregnant (indirectly) with her own granddaughters. "Embryonic development [of her eggs] actually begins in a mother’s body before her own birth, and two subsequent generations may be telescoped within each “grandmother.” (Stephen Jay Gould, Ontogeny and Phylogeny).

Akatsukami, what you say is more or less true, though a bit oversimplified. There is a massive meltdown of sorts in the tissues of a caterpillar when it is metamorphizing, and these are almost completely reorganized to form the adult. I don’t think I would characterize it as “dissolving into mere nutrients”, as some of the organ systems must continue to function in the pupa. I will get back to you with more details.

22

I’ll take the easier question first, which is that of exegisis. Yes, like many parthenogenetic species, aphids do sometimes have sex. This may occur through a sort of “alternation of generations,” in which one sexual generation is suceeded by several parthenogenetic ones which are then suceeded by another sexual one. Basically parthenogenesis is good for rapid increase in a stable environment. You can increase rapidly because you don’t have to waste time or energy on such frivolous things as courtship, sex or males. However, sexual reproduction, because it allows genes to recombine in different arrays, is better for coping with a changing environment. With aphids, there are additional complications in that there are both winged and wingless forms. The winged forms colonize new host plants, and they are induced by crowding. Sexual generations, in the temperate zone at least, seem to be induced by changes in day length; when the days get shorter sexual forms are produced, and these lay the eggs that overwinter. The gall midges I mentioned in Cecil’s article are similar; the paedomorphic parthenogenetic forms occur principally when they are colonizing almost unlimited food sources like fungus beds. Once crowding occurs or food becomes short they produce true winged sexual adults, which can disperse and colonize new food sources.

And yes, parthenogenetic aphids are often born pregnant. So a mommy aphid may actually be pregnant (indirectly) with her own granddaughters. “Embryonic development [of her eggs] actually begins in a mother’s body before her own birth, and two subsequent generations may be telescoped within each ‘grandmother.’” (Stephen Jay Gould, Ontogeny and Phylogeny).

Akatsukami, what you say is more or less true, though a bit oversimplified. There is a massive meltdown of sorts in the tissues of a caterpillar when it is metamorphizing, and these are almost completely reorganized to form the adult. I don’t think I would characterize it as “dissolving into mere nutrients”, as some of the organ systems must continue to function in the pupa. I will get back to you with more details.

23

oops

24

Cecil writes about parthenogenesis in turkeys:
http://www.straightdope.com/columns/991008.html

25

[[There is a massive meltdown of sorts in the tissues of a caterpillar when it is metamorphizing, and these are almost completely reorganized to form the adult. I don’t think I would characterize it as “dissolving into mere nutrients”, as some of the organ systems must continue to function in the pupa. I will get back to you with more details.]]

George or Doug, please do. This sounds pretty interesting.

  • Jill
26

Irishman:

Of course not! Can’t you follow the previous discussion of this, for Pete’s sake?! Pete, Jr. is the namesake. His old man is the name’s source.As with the chicken and the egg, I don’t know which came first, the butterfly or the caterpiller; but they both surely came before Caterpillar vehicles, don’t you think (whatever poetic lexicographers think)?

Duck Duck Goose:

You were OK up until this point (except that my post had no serious concern). My final question was clearly about Caterpillars (“earthmovers”), not caterpillars. (So, if the entomologists around here want to claim there are organic earthmoving caterpillars, I’m was ambiguous, but I don’t think there are any.) I just have noticed there there continue to be more and more Caterpillar vehicular implements around [link for general audience of any number of wheels, though could be construed as commercial spam, though I have no interests in this outfit], even of different species (but of one brand), so I figured they must have some way of reproducing. . .and had maybe even found a way to metamorphose in other species.

Uh. . .straighten your uniform before coming out from behind the couch.

Colibri: Of course, I suffered no insult. I thought my OP was shallow enough not to deserve analysis to anywhere near the degree it received here. But to worm into that pack of deadpan nitpickers, without my having a PhD in either tropical entomology or Sorbian petic etymology was perhaps as disturbing as that flutter-by in the Amazon that every storm gets blamed on.

But, so, how does that song “I’m My Own Grandpa” work out with parthenogenetic aphids?

(After that, you can answer why I should believe that the source of the Amazon is that point within its headwaters that is farthest from its mouth. [See an AP article on this date, as to such having been found.] Why shouldn’t I hold that the source of a river is the location found from following, upstream, each largest (cu-ft/sec) tributary, at each confluence, until such route’s last drop is reached? That’s certainly more logical. . .if not more poetic.)

Ray (If ever I am tempted to post to the SDMB again, I’ve got not to check for the autoresponderresponder. What a waste of time.)

27

Whew! Glad we cleared that up!

28

To continue with the answer to Akatsukami’s question:

Caterpillars, and the larvae of other insects that have complete metamorphosis, do undergo a pretty massive internal reorganization during the pupal stage. Some organ systems maintain continuity of function although they may change substantially in size. The heart often grows without marked change, while the nervous system both grows and changes its organization. The digestive system is changed by the growth or reduction of some parts and the modification of others.

However, other tissues, in particular many muscles, the larval “fat body” (a specific structure), and some others may break down almost completely. Obviously the muscles needed to move a sluggish caterpillar won’t serve very well if you want to put a butterfly in the air. Certain white blood cells (leucocytes) and enzymes break these tissues down into “a nutritive matrix capable of being transported by the blood to growing tissues.” (H. Ross, A Textbook of Entomology). These nutrients are then funneled to the rapidly growing new tissues.

Akatsukami’s idea of reactivated embryonic tissue is true for some organs but not all. At an early stage of development some embryonic tissue is segregated into groups of cells called anlagen (singular anlage), which are destined to form certain adult structures. These are essentially dormant in the larva, but grow rapidly once metamorphosis begins. The simple eyes and legs of caterpillars play no part in the development of their adult counterparts, but are “discarded.” The wings, legs, eyes and antennae of adults all develop from these previously-existing anlagen.

So Akatsukami is correct in several respects, although the image of a metamorphosing caterpillar being reduced to nothing more than a bag of nutrient goo on its way to being reconstituted as a butterfly is way too simplistic.

As a footnote to exegisis’s query, there are a number of parthenogenetic species in which males are never known to occur. Certain lizards and salamanders come to mind. In many cases they seem to be of hybrid origin, that is, produced by the crossing in nature of two previously existing species. For genetic reasons I won’t go into here, the hybrids are unable to reproduce sexually but get around this small problem by going the parthenogenetic route.

29

Cnemidophorus neomexicanus the New Mexico Whiptail is an all female species – a hybrid of the Western Whiptail which lives in the desert, and the Little Striped Whiptail of the grasslands.

30

Colibri blabbered:

Who you calling sweaty? And so what if I like to sleep a lot? :smiley:

NanoByte said:

Dawning comprehension It finally becomes clear! I guess picmr was right in the first place. Here I thought he was purposely distorting the meaning for comedic effect. Rather, it was your comedic effect he was interpreting for the linguistically challenged. Suddenly “earthmoving namesakes” makes the connection between crawly bugs and bulldozers that somehow eluded me. (Note to self: “namesake” is the one named in honor, not the one who’s name is used. Friggin English.) :wink:

31

Yes indeedy. As his subsequent posts make, uh, clear, and as difficult as it is to believe, he actually was asking about bulldozer sex in the OP! I think the preceding series of non sequiters helped throw all of us off. I detect symptoms of a severe, perhaps even terminal, case of paronomasia. And once an engineering background was mentioned, many other things that had been enigmatic suddenly became clear.

While it has been some time since I have been behind the controls of a D-9 (oh for the carefree days of my youth in the open-pit mines of Wyoming!) as I recall they generally do “it,” whatever “it” is, with the aid of a powerful diesel engine and a universal coupling.

The most common meaning of “namesake” is “something that has been named after another.” However, a broader meaning is “something with the same name as another,” without implication as to which was named first.

You obviously are Irish, aren’t you! :wink: (I can tell because my mother is Irish.)

32

Irishman marveled to himself:

So, do you have an equivalent, either way around, in Gaelic?

Colibri waxed:

Seems no more than an act of that distant Amazonian butterfly is required to do this minor displacement from barely on to off. These SDers must be all on the same circuit with a faulty switch, said the ex-EE. And look at the hyperlinguisticator: Now he can’t even spell ‘non sequitur’. Just dunno.

I’ll admit, I had to look up that ‘paronomasia’, though. Seemed like it oughtta be some meanderin’ arm o’ that largest of all continents.

Yeah, and «goodness’ sake» is something with the same goodness as that of another, right. But here are some good name sakes.

Ray

33

NanoByte remarked:

Sorry, don’t know Gaelic. There seems to have been some confusion. I’m American. (Note to self: your name is misleading - indicate when you’re being ironic in reference to language skills.)

34

Sure an’ begorrah! ‘Tis “paradimethylaminobenzaldehyde” you’ll be thinkin’ of!

35

Please do not adjust your sets. The malfunction appears to be originating at the transmitter rather than the receiver. Remain calm; all is well.

36

paronomasia. n. 1. a pun. 2. the act or practice of punning

I’d rather be a hyperlinguisticator than a gelogenic paronomasiac! :stuck_out_tongue:

Actually rather a good one, NanoByte. I will give you credit where credit is due. But I prefer to be considered simply a practictioner of charientism and grandiloquism.

The problem with the OP was that you tried a very difficult triple jump, and didn’t quite pull it off.

caterpillar = Caterpillar. - Not bad, really. So far so good.

Caterpillars = earthmoving namesakes. - A bit of a leap, but still in bounds.

How do bulldozers have sex? - Oh no! He spins out! Combining two jumps with a ridiculous question just puts too much strain on the suspension.

I will give you an 8 for concept, but I am afraid the execution left a lot to be desired, judging from audience response. Many more long hours of practice are clearly required. Preferably in a sound proof room. :wink:

37

gelogenic
charientism
grandiloquism

Note to self: get a better dictionary. :wink:

38

Yeah, you won’t find them in that Dictionary of Irishisms you’ve been using.

gelogenic = laughter-provoking
charientism = an elegantly veiled insult
grandiloquism = a lofty or imposing style of writing

39

And before we get completely carried away, won’t somebody please ask another question about bug whangers?

40

Colibri:

This audience is a benchmark? Shades of Mensa. Ever notice how words get in the way of good ideas? Implements aren’t manufactured anymore; they’re mechanofactured. (Those lexical types lag by centuries.) But with today’s genetic algorithms and genome deciphering, we’re now ready to genofacture, asexually, heterosexually, multiheterosexually, ad infinitum. (If you don’t like mixing Greek and Latin, tough.) Earthmoving Caterpillars ® against Godzilla ®.

For this territory, your SUV needs new shocks.

Not sure a grandiloquer of cherry jello will ever make it here. Calls for those with their pods on on terra firma.

Ray