Relation between reproduction and age


by manojr
Tags: relation, reproduction
manojr
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#1
Jun1-12, 01:52 AM
P: 62
In this Article there is a remark by biologist "It's one of the basic lessons in biology: Reproduction is very costly, and if you don't use it, you can live much longer".
Can someone give few examples of species that live longer if they don't reproduce?
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oli4
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#2
Jun1-12, 05:28 AM
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Well, there are some species, insects particularly for which reproduction will mean a very abrupt end of life, be it the male eaten by the female or the female dying while laying the eggs or giving itself as food to the little critters... :)
jackmell
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#3
Jun1-12, 06:48 AM
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How about elk? They really have to fight alot to mate, in general anyway. Helps if you got really big racks. But they're heavy and unwieldy; get caught in the bush when evading bears and all. But if an elk is to mate, big racks are better than small ones because of the competition for the females. By the time the big elks are finished, they're exhausted and that makes them easier prey.

256bits
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#4
Jun1-12, 08:32 PM
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Relation between reproduction and age


The act of reproduction and the production of young ones may be costly as oli3 stated. Competition for a mate can also be costly as jackmell stated.

A third aspect is caring for the young until they reach an age of maturity, which is evident for mammals, birds, and some species of reptiles, insects, fish etc.
Foraging for food for extra mouths in addition to your own means that the parent is out more often from a secure place and more prone to predation.
Incubating eggs or caring for the new young such as birds do would mean that the parent is now in one place and if found by a predator has to make the choice of fleeing and leaving behind the energy and time already spent to care for the potential young or challenging the threat with the possibility of life extinction.

You can even relate your question to humans where before the advances of hospital and medical care that certain societies enjoy now, the female had a greater chance of dying by giving birth ( as opposed to not having children ).
zoobyshoe
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#5
Jun2-12, 05:09 AM
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The article linked to is talking about a phenomenon whereby the butterflies actually stay younger longer when they're not in reproductive mode:

Biologists have long been fascinated by the innate and learned behaviors underlying animal migrations. When monarchs are breeding, for instance, they can live up to four weeks, but when they are migrating, they can live as long as six months.

"As the day length gets shorter, their sexual organs do not fully mature and they don't put energy into reproduction. That enables them to fly long distances to warmer zones, and survive the winter," de Roode says. "It's one of the basic lessons in biology: Reproduction is very costly, and if you don't use it, you can live much longer."
Something like this must be in play with salmon as well, who seem to curl up and die soon after they get their mating accomplished.
jackmell
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#6
Jun2-12, 09:31 AM
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Surely there are many salmon migrating up the Columbia that never get to mate. Do these live longer than the ones that mate? How about even more drastic: suppose I corner a group of migrating salmon just before they get to their final location, after they have made the arduous trip, and I prevent them from mating. Will this group of salmon live longer than the ones that are allowed to mate?

A correction: the ones that mate do die. So if I corner them right before they mate, and prevent them from mating will they still die? Is it the trip that killed them or some reproductive event that causes them to die?
zoobyshoe
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#7
Jun3-12, 02:40 AM
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Quote Quote by jackmell View Post
Surely there are many salmon migrating up the Columbia that never get to mate. Do these live longer than the ones that mate? How about even more drastic: suppose I corner a group of migrating salmon just before they get to their final location, after they have made the arduous trip, and I prevent them from mating. Will this group of salmon live longer than the ones that are allowed to mate?

A correction: the ones that mate do die. So if I corner them right before they mate, and prevent them from mating will they still die? Is it the trip that killed them or some reproductive event that causes them to die?
As the salmon comes to end of its ocean migration and enters the estuary of its natal river, its energy metabolism is faced with two major challenges: it must supply energy suitable for swimming the river rapids, and it must supply the sperm and eggs required for the reproductive events ahead. The water in the estuary receives the freshwater discharge from the natal river. Relative to ocean water, this has a high chemical load from surface runoff. Researchers in 2009 found evidence that, as the salmon encounter the resulting drop in salinity and increase in olfactory stimulation, two key metabolic changes are triggered: there is a switch from using red muscles for swimming to using white muscles, and there is an increase in the sperm and egg load. "Pheromones at the spawning grounds [trigger] a second shift to further enhance reproductive loading."[36]
The salmon also undergo radical morphological changes as they prepare for the spawning event ahead. All salmon lose the silvery blue they had as ocean fish, and their colour darkens, sometimes with a radical change in hue. Salmon are sexually dimorphic, and the male salmon develop canine teeth and their jaws develop a pronounced curve or hook (kype). Some species of male salmon grow large humps.
The condition of the salmon deteriorates the longer they remain in fresh water. Once the salmon have spawned, most of them deteriorate rapidly and die. This programmed senescence is "characterized by immunosuppression and organ deterioration."
http://en.wikipedia.org/wiki/Salmon_run

In the case of the butterflies, they remain immature due to short days. Becoming sexually mature and mating doesn't really seem to be the cause of their demise, it's the fact longer days cause them to age. The salmon seem to be the same: it seems it's primarily the long term exposure to fresh water that causes the changes that burn them out, not the mating itself.

Your question remains unanswered, though. What would happen if we, say, blocked off a river and prevented the salmon from going up to spawn? Would they live indefinitely or would this cause some other problem that killed them? I don't know. The quote seems to say they'd have the choice of not reproducing and living longer thereby. I tend to doubt that: that they're capable of making any such choice.
jackmell
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#8
Jun3-12, 06:35 AM
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Ok, thanks for that. The paragraph, "The Spawning" suggest they do deteriate rapadily during the run but some survive after spawning and return to the ocean and recover.
tkjtkj
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#9
Jun4-12, 10:23 PM
P: 41
'Death' actually evolved as a consequence of sexual reproduction.

Note that the dividing amobae never must die, and so it is with every asexually-reproducing organism. All sexually-reproducing organisms have a typical 'life span', which is not true for asexually-reproducing species.

ref: a lecture by Dr. George Wald, at B.U. in the 1970's
manojr
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#10
Jun6-12, 06:23 AM
P: 62
Hey, thank you all for the information.
Darwin123
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#11
Jun7-12, 10:55 AM
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Quote Quote by manojr View Post
In this Article there is a remark by biologist "It's one of the basic lessons in biology: Reproduction is very costly, and if you don't use it, you can live much longer".
Can someone give few examples of species that live longer if they don't reproduce?
All those animals whose parents die immediately after reproduction.
I am not sure this is exactly what you meant. However, a lot of animals die immediately
after the act of reproduction. One of the selective advantages of such behavior is that
the parent won't eat the child. Another reason is that the act of child care uses up
the parents resources.
Sometimes, the parent provides nourishment for the child or other parent. This is
an example of resource competition. Males often get eaten because the act of
laying eggs weakens the mother.
Here are some examples.
1) The octopus mother stops eating after laying her eggs, tends the nest and dies of starvation.
-She would eat the eggs if she didn't lose her appetite.
2) Salmon stop eating and die soon after laying their eggs.
-The mother guards here eggs and stops eating.
-She would probably eat the eggs if she didn't lose her appetite.
3) The male large mouth bass stops eating for two weeks after fertilizing his eggs.
-The male guards the nest during his fast.
-He starts eating about 2 weeks after the eggs are left, if he is still alive.
However, he is badly weakened by his fast. He has an increased chance of being killed
after he mates.
4) The male of most species of spiders are killed by the female immediately after
mating.
-By eating the male, the female gets enough strength to raise another brood.
5) The female of many species of spiders dies immediately after laying eggs.
-Again, she would probably eat them if she didn't die.
6) The male preying mantis is beheaded by the female during mating.
-By eating the male, the female gathers enough strength to raise another brood.
7) Human females have a high chance of dying during childbirth.
-The rate of dying during childbirth was a lot greater before the advances in
modern medicine.
-In primitive societies, a woman can seriously reduce her life expectancy
by having children.
8) Venereal diseases of all animal species can only infect a host if the host
indulges in reproductive behavior.
-Syphilis, gonorrhea, HIV, SIV, etc.
Darwin123
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#12
Jun7-12, 11:51 AM
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Quote Quote by zoobyshoe View Post
http://en.wikipedia.org/wiki/Salmon_run

In the case of the butterflies, they remain immature due to short days. Becoming sexually mature and mating doesn't really seem to be the cause of their demise, it's the fact longer days cause them to age. The salmon seem to be the same: it seems it's primarily the long term exposure to fresh water that causes the changes that burn them out, not the mating itself.
This is not true. The salmon adapt quite nicely to both fresh and salt water. The
salmon that survive the trip are killed by their eggs or their milt.
Please recall that salmon fertilize externally. So mating is just the final step
of reproduction.
The female dies because the eggs make her lose her appetite. Of she lays
her eggs, she will starve. If she doesn't lay her eggs, the pressure of the eggs
will kill her. Either way, the eggs kill her.
The male dies soon after it sprays its milt on the eggs. The production of milt
takes so much out of him that he is weakened. So he dies. If he doesn't spray his
milt, the pressure would kill him. Either way, the milt kills him.
Hence, it is the internal changes of reproduction that kill a salmon if the trip doesn't kill it. The trip will may kill the salmon, but the reproduction surely will kill the salmon.

>Your question remains unanswered, though. What would happen if we, say, blocked off a >river and prevented the salmon from going up to spawn?
I wonder how they raise salmon in farms? I have to find out. I will get back to you.
> Would they live indefinitely or would this cause some other problem that killed them?
I don't know. However, I know that starting reproduction does kill them.
> I don't know. The quote seems to say they'd have the choice of not reproducing and living longer thereby.
In the wild, they would probably die when the weather changed. The reason that
they migrate is because the weather changes in each location. If a salmon were
prevented from migrating and forced to live in stable weather conditions, then I
don't know. However, the beginning of the reproductive act kills them.
The eggs and milt kill all salmon that survive the trip. The eggs and milt don't
have to be joined as in mating. However, it is the eggs and milt that kill all surviving
salmon.
> I tend to doubt that: that they're capable of making any such choice.
I don't know either. Probably not. Anyway, they would need instincts to survive
the world after the trip. Natural selection may not have provided them with such
instincts, since reproduction reliably kills them.
A salmon in the wild that doesn't reproduce may wonder what to do next!
A salmon that whose body doesn't make eggs or milt may be very strong after
the mating season. Further, he may be asking himself the following question.
Should I stay in the river and risk the winter, or try to make another go round and
risk the trip? Mutations that do that do either are not likely to leave progeny.
This possibility is irrelevant. The answer to your question is that reproduction kills the salmon that survive the trip. Reproduction does use up resources that could have
been used for long term survival.
manojr
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#13
Jun8-12, 02:28 AM
P: 62
Good to know all these examples.

Wondering whether any plant dies after releasing seeds?
jackmell
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#14
Jun8-12, 07:27 AM
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How about Harpy eagles:

These eagles prey upon the local monkey population. Yum. But when they have offspring, the parents, in one study at least, didn't go after the local ones but rather far away to get them. The biologist studing this phenomenon suggested they were saving the local ones or "desensitizing" them in preparation for their offspring to more easily predate them: the act of reproduction causes strain in the adult, in this case by causing them to expend more energy to obtain food.
Darwin123
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#15
Jun8-12, 04:40 PM
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Quote Quote by manojr View Post
In this Article there is a remark by biologist "It's one of the basic lessons in biology: Reproduction is very costly, and if you don't use it, you can live much longer".
Can someone give few examples of species that live longer if they don't reproduce?
I have given several examples. However, I skipped premating combat.
A lot of animals fight over mates. Usually, it is the male that fights over mates. The male often gets killed. If a male didn't try to fight the other males, it is more likely to live long. However, if it doesn't fight it has less of a chance of reproducing. Thus, the initiation of mating behavior shortens the average lifetime of the male.
I read someplace that a male lion in wild Africa has a four out of five chance of being killed by another male lion. Thus, looking for a mate is very risky for a male lion. A male lion
that doesn't even try to mate can live much longer. For a wild lion male, combat with other males is necessary to initiate reproduction.
Again, that biologist should have said that "Initiating reproduction is very costly." Just because an animal skips one small part of the reproductive process doesn't mean that it
is going to live longer. Usually, the very initiation of reproductive activity is costly. With this caveat, the biologist is right.
If you decide not to look for a sex partner and not raise a family, your average lifespan will go up. However, your chance of propagating yourself into the next generation goes way down.
Of course, lots of animal species have mixed strategies. Different individuals have different strategies for survival. Statistically, the population can take full advantages in
the trade off between lifespan and birthrate. However, mixed strategies are another matter.
Pythagorean
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#16
Jun8-12, 04:44 PM
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As a parent of two, I'll just say anecdotally that expending resources to raise humans is expensive on time, resources, energy, etc. You luckily get a set of hormones (or something) that BS your into enjoying it though, but my grey hair conversion rate is multiplying.

And your kids aren't going to survive if they don't get raised by an intelligent enough mammal, so you could arguably associate raising costs to reproductive costs.
BlackTentacle
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#17
Jun11-12, 02:02 PM
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It's interesting to note too that many parasites have evolved to render their hosts infertile increasing the host lifespan and therefore their own. I'm not sure what species of parasite have evolved to do this specifically as they have such complicated life cycles and can alter the hosts hormones for their benefit anyway.

I believe in history human eunuchs have been very large and also suffer from weight problems probably gained from the extra energy saved. So I started to wonder about animals that were born sterile such as cross-breeds but it seems to be a complicated issue with genetics and hormones. Mules are said to live longer according to one aficionado on Wikipedia. Also I suppose being sterile doesn't mean your not expending the energy to produce sperm and eggs. Then again, from reading forums, some guys have mentioned that after they lost their virginity they began to produce more semen and would thus expend more energy. So it will be interesting to note how reputed virgin Sir Cliff Richard lives. I hope I haven't meandered too far.


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