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Author Topic:   Egg burier animals question
Garabato
Junior Member (Idle past 5987 days)
Posts: 8
Joined: 10-24-2007


Message 1 of 29 (438680)
12-05-2007 6:42 PM


Hi.
I have a question regarding animals like the Maleo (Maleo - Wikipedia) that bury their eggs deep in the ground, and how the young birds are able work their own way up through the sand.
How did that incubation method probably evolved? If the young birds didn't had the ability to dig up then they would have becomed extinct as the mother burried into the ground; but the ability to dig up would be useless otherwise.
Whats the current scientific explanation for the evolution of animals that bury their eggs in the ground?
Thanks
Edited by Garabato, : No reason given.
Edited by Garabato, : Spelling mistakes

Replies to this message:
 Message 2 by AdminNosy, posted 12-06-2007 12:35 AM Garabato has replied
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AdminNosy
Administrator
Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 2 of 29 (438728)
12-06-2007 12:35 AM
Reply to: Message 1 by Garabato
12-05-2007 6:42 PM


A suggestion first
Welcome to EvC Garabato. Thanks for joining us.
I think it would help people answering your question if we knew more about what you already understand or don't understand.
Perhaps you can explain more what your view and understanding is.
My reason for asking for this is particularly this sentence:
How did that incubation method probably evolved? If the young birds didn't had the ability to dig up then they would have becomed extinct as the mother burried into the ground; but the ability to dig up would be useless otherwise.
This hints that you know nothing at all about the evolutionary model. If that is the case you might to better to ask questions of a more general nature. Then you should find this question very easy to answer yourself.
You can find a number of other questions just like this one. They often involve things like how can a symbiotic relationship develop, how can sexual organisms arise (often asked like this: "how can a male appear if it has no female to mate with) and so on. In all cases the answer is, at a high level the same and when you have just a beginners understanding of evolutionary science you will be able to answer it.
As a clue: think gradual.
You can add more to your opening post (OP) and then reply to me and I will consider what you have then. Or you can leave this and ask questions in other threads.

This message is a reply to:
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Garabato
Junior Member (Idle past 5987 days)
Posts: 8
Joined: 10-24-2007


Message 3 of 29 (438732)
12-06-2007 1:22 AM
Reply to: Message 2 by AdminNosy
12-06-2007 12:35 AM


Re: A suggestion first
Thanks for the suggestion AdminNosy. I probably failed to make myself clear. My question was not regarding how two interdependent features could have evolved as my first post made it sound, I ment to ask the specific question of how did the Maleo's egg burial feature evolved.
Thinking gradually as you said I could especulate something. Birds already have to get trought a strenuous process to extract themselves from an unburied egg. One could imagine the early stages of the evolution of egg burying involving a very shallow layer of dirt that way, so the diference wouldn't be so sudden.
Now since there are evolutionary advantages for deeper burial (I think). Then there is selective pressure for greater depth of burial. So after many generations of slightly increase of burial depth, the individuals who had slightly increase of physical activity to reach the surface would have a higher chance of surviving, thus having a higher chance to leave offspring.
I dont know if it goes like that, my understanding of the evolution model is pretty limited to be honest. But the thread was regarding the current scientific explanation of this feature from an evolutionary perspective, hope that clears thing up.
Thanks

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AdminNosy
Administrator
Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 4 of 29 (438736)
12-06-2007 2:04 AM


Thread moved here from the Proposed New Topics forum.

  
PaulK
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Posts: 17838
Joined: 01-10-2003
Member Rating: 3.8


Message 5 of 29 (438743)
12-06-2007 2:26 AM
Reply to: Message 1 by Garabato
12-05-2007 6:42 PM


I don't know "the" explanation, but I can certainly speculate.
Relatives of the maleo bury their eggs in compost, so burying quite likely evolved before the maleo split from them. They bury the eggs in warm material, which has the advantage that the parent bird need not sit on the nest - which can be very dangerous for ground nesting birds.
So I'd suggest: Burial in warm material allows the parents to spend more time away from the nest. At this point the parent still looks after the nest and helps the young birds out. Some young birds are lost because they can't dig themselves out, even with help, but overall it's a plus.
This situation becomes more extreme. As the young birds get better at digging themselves out, they can be buried deeper and/or the parents need to spend less time at the nest. (This sort of balancing is expected in evolution) so the need to be able to dig ratchets up and evolves.
So:
Originally the young birds would have been helped by their mother. They didn't need to dig themselves out on their own.
As they got better at doing without their mother, so the mother's involvement declined (because the life of the mother is more important than the life of one chick). The mother would often be away when a chick hatched, and so the chick needs to dig itself out at least enough to breathe. I'd guess that this also produced a pressure for the chicks to be more fully developed when they hatched, needing less parental support after hatching - largely because the more developed chicks would be better at digging.
The process continued, getting more extreme. It was always an advantage for the chicks to be better at digging - but any improvement in digging can be exploited by the parent spending less time at the nest, for a greater overall advantage.
Now maybe I'm overlooking something but - on the little information I have - that account looks basically plausible.

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Zucadragon
Member
Posts: 93
From: Netherlands
Joined: 06-28-2006
Member Rating: 2.8


Message 6 of 29 (438754)
12-06-2007 3:49 AM
Reply to: Message 3 by Garabato
12-06-2007 1:22 AM


Re: A suggestion first
Thinking gradually as you said I could especulate something. Birds already have to get trought a strenuous process to extract themselves from an unburied egg. One could imagine the early stages of the evolution of egg burying involving a very shallow layer of dirt that way, so the diference wouldn't be so sudden.
Now since there are evolutionary advantages for deeper burial (I think). Then there is selective pressure for greater depth of burial. So after many generations of slightly increase of burial depth, the individuals who had slightly increase of physical activity to reach the surface would have a higher chance of surviving, thus having a higher chance to leave offspring.
Well, this certainly sounds like a plausible explenation, I think you just answered your own question.. With plausible I mean that it could be some of the ways that would give the birds an advantage over those who don't bury their eggs.
You are correct in stating that gradually exposing its eggs and offspring to more depth would give certain offspring a bigger advantage if those offspring had a mutation that managed to exploit it.

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jar
Member
Posts: 34059
From: Texas!!
Joined: 04-20-2004
Member Rating: 4.9


Message 7 of 29 (438788)
12-06-2007 9:51 AM
Reply to: Message 3 by Garabato
12-06-2007 1:22 AM


Working it out.
So far you are doing a great job of working it out. Another question you might ask is whether or not the idea of burying eggs that hatch and the hatchlings then need to dig their way out is that unusual? Are there other such examples?
Think sea turtles.

Immigration has been a problem Since 1607!

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Replies to this message:
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bluescat48
Member (Idle past 4274 days)
Posts: 2347
From: United States
Joined: 10-06-2007


Message 8 of 29 (438890)
12-06-2007 1:46 PM
Reply to: Message 7 by jar
12-06-2007 9:51 AM


Re: Working it out.
or a number of insect species.

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EighteenDelta
Inactive Member


Message 9 of 29 (438899)
12-06-2007 2:00 PM
Reply to: Message 7 by jar
12-06-2007 9:51 AM


Re: Working it out.
Or Crocs and gators.
-x

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arachnophilia
Member (Idle past 1428 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 10 of 29 (438911)
12-06-2007 3:11 PM
Reply to: Message 9 by EighteenDelta
12-06-2007 2:00 PM


Re: Working it out.
crocodilians would be the obvious and most pertinent example. aside from birds, crocodiles are the only currently thriving branch of archosaurs. they also bury their eggs. they do this because they're not endotherms. egg mounds serve to incubate the eggs. temperature also control gender.
we know that some dinosaurs appear to have done something very similar, though they seem to have generally covered their eggs with their own warm-blooded bodies. basically, egg-burying birds are sort of a throw-back, retaining crocodilian habits.
Edited by arachnophilia, : word choice


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MartinV 
Suspended Member (Idle past 5913 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 11 of 29 (438913)
12-06-2007 3:20 PM


But the thread was regarding the current scientific explanation of this feature from an evolutionary perspective, hope that clears thing up.
There is no such thing as "scientific explanation of this feature". All explanations are only fantasies and pressupostions. The better fantasy you have the better neodarwinian scientist you are (see Richard Dawkins).
The great saltationist Goldschmidt was once arguing that he coudn't imagine gradual evolution of something. The aswer was that it is only due to lack of his imagination he didn't see it. Neodarwinism is very often only story invention which changes as soon as better story-teller pops up.
I wouldn't be surprised if next to the M. maleo holes with eggs there would be nests of another bird species which do not bury their eggs. Birds species that do not profit "small survival advantages" of burrying their eggs. I suppose there are many bird species in the area which do not bury their eggs but thrive as well as M. maleo there.
Edited by MartinV, : No reason given.

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AdminNosy
Administrator
Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 12 of 29 (438915)
12-06-2007 3:23 PM
Reply to: Message 11 by MartinV
12-06-2007 3:20 PM


No, No Martin
You may clutter up you mimicry thread with you unfounded assertions. You will be suspended if you start spreading the nonsense around.

This message is a reply to:
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MartinV 
Suspended Member (Idle past 5913 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 13 of 29 (438922)
12-06-2007 3:35 PM
Reply to: Message 12 by AdminNosy
12-06-2007 3:23 PM


Re: No, No Martin
AdminNosy,
here is the list of birds species which live in Sulawesi where
Macrocephalon maleo is endemic. It is pretty long list I would say. If somebody claims that Macrocephalon maleo bury their eggs because it gives them some survival advantage I would like to know how many Sulawesi species do the same. PaulK mentioned relative species without naming them.
Such behaviour is not very common amongst birds and further study is needed before making rash conclusions.
Thank you.
http://www.bsc-eoc.org/avibase/checklist.jsp?lang=EN®i...

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Replies to this message:
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arachnophilia
Member (Idle past 1428 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 14 of 29 (438931)
12-06-2007 3:59 PM
Reply to: Message 13 by MartinV
12-06-2007 3:35 PM


Re: No, No Martin
here is the list of birds species which live in Sulawesi where
Macrocephalon maleo is endemic. It is pretty long list I would say. If somebody claims that Macrocephalon maleo bury their eggs because it gives them some survival advantage I would like to know how many Sulawesi species do the same.
you have completely misunderstood evolution. it is not survival of only the most fit, but survival of everything that except the least fit. a small survival advantage is, frankly, enough for the retention of a feature. no net effect is enough for the retention of a feature. and if there is some small advantage, that does not mean that EVERY similar animal would likewise spontaneously evolve a covergent feature or become extinct.
in any case, this is not what people are arguing. if you'll notice above, my argument is that it's a throwback to crocodilian practices.
Such behaviour is not very common amongst birds and further study is needed before making rash conclusions.
but such behaviour is the norm for other branches of archosauria.


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clpMINI
Member (Idle past 5249 days)
Posts: 116
From: Richmond, VA, USA
Joined: 03-22-2005


Message 15 of 29 (438933)
12-06-2007 4:08 PM
Reply to: Message 13 by MartinV
12-06-2007 3:35 PM


Other Megapodes
You wanted more on related species...lets return to lovely wikipedia:
Megapode - Wikipedia
There is a description of behaviours and a list of the species. They are commonly known as "incubator birds" as they all bury their eggs as opposed to sitting on them, and they are all terrestrial.
It even mentions that it is likely that temperature determines sex, making the message by Arach concerning a throwback to crocs even more meaningful.

I mean, this is America. Everybody loves seeing lesbians go at it, as long as they are both hot and not in a monogamous, legally sanctioned relationship.

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