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Author | Topic: Egg burier animals question | |||||||||||||||||||||||
arachnophilia Member (Idle past 1343 days) Posts: 9069 From: god's waiting room Joined: |
that they are terrestrial (as opposed to arboreal) is probably important.
It even mentions that it is likely that temperature determines sex, making the message by Arach concerning a throwback to crocs even more meaningful. yes. i wasn't sure if that was the case in mound-building birds, but vaguely recalled that it might have been, as in crocodiles.
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MartinV  Suspended Member (Idle past 5828 days) Posts: 502 From: Slovakia, Bratislava Joined: |
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.
And perhaps it is you who do not realize into depth what you are talking about. Go to Mimicry thread we can discuss "survival advantage" and "fitness" there generally and in particular cases.
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.
That's more interesting as the reasoning of PaulK. Do you mean that genes for such behaviour were inherited from dinosurian ancestors and were somehow switched on? You know I like frontloading, epigenesis etc.. I suppose this is what you means. Otherwise if such genes has arisen de novo I wouldn't call such obviously innate and fixed behaviour as "throwback".
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reiverix Member (Idle past 5818 days) Posts: 80 From: Central Ohio Joined: |
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.
But wouldn't it be a disadvantage if the other species were all doing the same? There's only so much good real estate for egg burying.
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arachnophilia Member (Idle past 1343 days) Posts: 9069 From: god's waiting room Joined: |
That's more interesting as the reasoning of PaulK. Do you mean that genes for such behaviour were inherited from dinosurian ancestors and were somehow switched on? crocodilians and basal archosaurs seem to have buried their eggs, and used tempurature to control gender. i'm not too clear on early dinosaurs, though the transition from cold-blooded to warm-blooded seems to have occured prior to dinosaurs' divergence, within crocodilians like postosuchus. dinosaurs as a whole seem to have continued using egg-mounds, though in various different styles. i seem to recall that both ornithischians and saurischians tended their eggs in open nests, but that sauropods (unlike other saurischians) buried them due to the impracticality of sitting on them. in other words, in this particular evolutionary tree, egg-burying came and went a few times (much like flight). tempurature's relation to gender might be common to the whole lineage, and egg burying may simply be a common solution for controlling temperature. Edited by arachnophilia, : No reason given.
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nator Member (Idle past 2169 days) Posts: 12961 From: Ann Arbor Joined: |
quote: I wouldn't be surprised, either. It's called a "niche".
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Dr Adequate Member (Idle past 284 days) Posts: 16113 Joined: |
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. Yes, that seems about right. As someone noted, in the early stages maybe the mother would assist. I notice that all megapodes are born active, feathered, and even able to fly; apparently they dig their way out of the "nests" with large powerful claws. One wonders whether this precocious development is an adaptation to the egg-burying habit, or an exaption that allowed the evolution of the habit. Interesting birds.
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MartinV  Suspended Member (Idle past 5828 days) Posts: 502 From: Slovakia, Bratislava Joined: |
in other words, in this particular evolutionary tree, egg-burying came and went a few times (much like flight). tempurature's relation to gender might be common to the whole lineage, and egg burying may simply be a common solution for controlling temperature.
Do you think there was a time M.maleo ancestors nested and hatched their eggs like other birds and only their descendants (more recent M.maleo ancestors) started burrying their eggs? In that case - because the process seems to be instinctive - do they use some inherited and switched on ancestory genes? Scientists should also make an experiment what the birds would do having no possibilities to burrow their eggs into sand. Would they hatch them or would they leave their eggs on the ground and would not care about them?
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jar Member (Idle past 393 days) Posts: 34026 From: Texas!! Joined: |
Scientists should also make an experiment what the birds would do having no possibilities to burrow their eggs into sand. Would they hatch them or would they leave their eggs on the ground and would not care about them? Other than the somewhat stupid suggestion that we increase the pressure on an already endangered species, what would that show? I can tell you. It would show evolution in action. Those traits that successfully reproduced in that environment would gradually come to dominate the population. Those that did not would die out or move. Plain old TOE stuff Martin. Immigration has been a problem Since 1607!
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Granny Magda Member Posts: 2462 From: UK Joined: Member Rating: 4.0 |
Hi MartinV,
You ask; MartinV writes: Do you think there was a time M.maleo ancestors nested and hatched their eggs like other birds and only their descendants (more recent M.maleo ancestors) started burrying their eggs? Well, I suppose that depends what you mean by other birds. Most birds are arboreal nesters and I cannot imagine that any megapode ever did that. They may well have nested on the ground, in a very simple nest, much like thousands of other bird species. At this remove we can only speculate (short of digging up half of Sulawesi looking for nest fossils) but there seem to be two possibilities; either the megapodes and their ancestors have always done this, right back to their Archosaur ancestors, or the behaviour re-emerged at some point, from a previously switched-off gene or a novel mutation. My bet is that the behaviour was always present. Maybe it got switched off/switched back on at some point, but I think the novel mutation sounds a bit much of a coincidence.Fun to speculate, but it doesn't really prove anything. Mutate and Survive
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MartinV  Suspended Member (Idle past 5828 days) Posts: 502 From: Slovakia, Bratislava Joined: |
My bet is that the behaviour was always present.
OK. It contradicts clearly other theories proposed here. What is interesting is that validity of all these theories can be supported very well by different images of natural selection. I am afraid if anyone here proposed another theory of arising of egg burrying behaviour he would backs it up by some natural selection explanation as well. So we don't know how the behaviour has arisen. But what we know in advance is that it is "plain old TOE stuff" as jar has written it. Edited by MartinV, : No reason given. Edited by MartinV, : No reason given.
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Granny Magda Member Posts: 2462 From: UK Joined: Member Rating: 4.0 |
MartinV writes: Granny writes: My bet is that the behaviour was always present.
OK. It contradicts clearly other theories proposed here. I'm not sure that it does, maybe I should make myself more clear. By "always present" (an admittedly clumsy phrase) I mean that the behaviour was probably already available to the ancestors of the maleo. It may or may not have been expressed in any given intermediate species. Just speculation really, based on its similarity to the behaviour of other related critters. Croc's buried their eggs (still do), as did some dinosaurs (plenty of dinosaur nests have been found) so it seems reasonable to speculate that some birds might have inherited this behaviour, rather than the maleo displaying convergent evolution. Either way, it is not a problem for the ToE. Mutate and Survive
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molbiogirl Member (Idle past 2641 days) Posts: 1909 From: MO Joined: |
Granny,
Be warned. MartinV is a notorious troll. Take a gander at the Peppered Moth thread. His running buddy, John A. Davison, has been banned here. JAD also has the distinction of his own page at http://www.crank.net. I'm just sayin'.
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RAZD Member (Idle past 1404 days) Posts: 20714 From: the other end of the sidewalk Joined: |
A better intro to MartinV is Mimicry and neodarwinism (which he started and is now closed) and Mimicry: Please help me understand how. Watch for head spinning circular arguments. That repeat.
My first impression is that it is fairly normal for ground dwelling egg laying animals to cover the eggs with debris while they go to feed, as hidden eggs are less likely to be found by predators than unhidden ones. That's all it takes to start a system of covering with selection for those that are better at hiding/burying. I don't have any problem with this behavior being re-evolved in many different applications. Enjoy. Edited by RAZD, : No reason given. we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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MartinV  Suspended Member (Idle past 5828 days) Posts: 502 From: Slovakia, Bratislava Joined: |
Edited by MartinV, : misplaced post Edited by MartinV, : moved to EvC Forum: Mimicry: Please help me understand how
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