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Author Topic:   Population Dynamics
godservant
Junior Member (Idle past 5820 days)
Posts: 24
Joined: 04-15-2008


Message 1 of 10 (463409)
04-16-2008 11:34 AM


Just some thoughts and questions maybe someone could answer. Not sure if these have been covered yet.
When life sprang up, how did it remain in a constant state of balance between herbivores/carnivores/omnivores?
Survival of the fittest
Carnivores eat herbivores, given lack of foliage for herbivore survival, both run out of food, herbivors die off, carnivor eats itself out-self distruct?
Herbivores would have needed appropriate digestive abilities to digest any available foliage currently available. Same beginning cells would have had to split at sometime to grow into plants as well as animals. both different cell make-up.
If only herbivores existed in the beginning, what would be the benefit or possiblity of becoming carnivorous given plenty of foliage?
If only carnivorous, would quickly eat itself out.
Had each group had to evolve in order to obtain their respective characteristics to ensure survival, how did they survive to begin with?
Edited by godservant, : No reason given.
Edited by AdminNosy, : No reason given.

Replies to this message:
 Message 2 by AdminNosy, posted 04-16-2008 1:28 PM godservant has not replied
 Message 4 by Rahvin, posted 04-16-2008 2:28 PM godservant has not replied
 Message 5 by Chiroptera, posted 04-16-2008 4:22 PM godservant has not replied
 Message 6 by molbiogirl, posted 04-19-2008 2:52 AM godservant has replied

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


Message 2 of 10 (463414)
04-16-2008 1:28 PM
Reply to: Message 1 by godservant
04-16-2008 11:34 AM


Title Change
I've taken the liberty of changing to a more useful title of your OP.
I'll prompt it now for discussion. You can also use it as a google search and do some reading yourself.
And a small warning:
What you know about these topics can be measured with negative numbers only. If you are receptive to learning then people will be polite (or else!!) and helpful to you. If you demonstrate an unwillingness to listen you may have to be suspended.

This message is a reply to:
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AdminNosy
Administrator
Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 3 of 10 (463415)
04-16-2008 1:29 PM


Thread moved here from the Proposed New Topics forum.

  
Rahvin
Member
Posts: 4032
Joined: 07-01-2005
Member Rating: 9.2


Message 4 of 10 (463421)
04-16-2008 2:28 PM
Reply to: Message 1 by godservant
04-16-2008 11:34 AM


Just some thoughts and questions maybe someone could answer. Not sure if these have been covered yet.
When life sprang up, how did it remain in a constant state of balance between herbivores/carnivores/omnivores?
Survival of the fittest
Carnivores eat herbivores, given lack of foliage for herbivore survival, both run out of food, herbivors die off, carnivor eats itself out-self distruct?
Herbivores would have needed appropriate digestive abilities to digest any available foliage currently available. Same beginning cells would have had to split at sometime to grow into plants as well as animals. both different cell make-up.
If only herbivores existed in the beginning, what would be the benefit or possiblity of becoming carnivorous given plenty of foliage?
If only carnivorous, would quickly eat itself out.
Had each group had to evolve in order to obtain their respective characteristics to ensure survival, how did they survive to begin with?
Hi godservant,
Your questions appear to be these:
1) How did plants, herbivores, and carnivores establish a balance that allowed them to coexist without driving each other to extinction?
First, you have to understand that at the fundamental level you're talking about, carnivores and herbivores are actually the same thing: organisms that live by consuming other organisms. Plants are different, because they live (mostly) off of direct mineral absorption and photosynthesis.
So why have the consumers not compeltely wiped out their source of food?
The answer is deceptively simple: some of them did. Hell, humans have hunted some species to extinction or near enough. For those organisms that were so voracious that they wiped out their food source, both predator and prey died. If both were located only in a single geographical area, both species could conceivably be wiped out completely.
Think of diseases. What are the most successful illnesses? Are they the ones that completely kill the host quickly? Or are they the ones that keep you sick and contagious for a very long period of time so that they can spread to new hosts?
The good news is that life is extremely varied. No single predator species can consume all other species. In the grand scheme of things, the loss of one or even ten species is relatively insignificant to the existence of life - other organisms will still exist and get along fine, or even better with the removal of competition. In our case, while we have hunted species to extinction, we haven't hunted all other life to extinction, so we are relatively unaffected by the loss of, say, the dodo bird (I know, we didnt hunt that one, but it still illustrates the point).
The panda bear is another good example - they have extremely specific dietary needs. Their consumption of their only food source coupled with human encroachment on their territory is eventually going to drive them to extinction. But species with a more flexible diet (just about every other species would fall in this category) survive much more easily.
So while some species do get hunted to extinction, and it's certainly possible that a predator species with an unflexible diet could wind up ensuring its own destruction as well with its voracious appetite, those species who do establish a balance through variety of diet will tend to survive more frequently.
It's a self-correcting system. Barring some magic superpredator that can consume all forms of life on the planet, there cannot be a worldwide dieoff-via-predator.
2) How did plants, herbivores, and carnivores separately develop?
This is also relatively simple with just a little knowledge of the process of evolution and the earliest forms of life.
The key to your misunderstanding here is the phrase "when life sprang up."
The earliest forms of life were unicellular (or even pre-cellular, depending on exactly how you define "life," but that's a seperate discussion). There were no delineations like plants, carnivores, and herbivores - life had not yet evolved such complexity.
The earliest forms of life were very likely little more than self-replicating molecules, imperfectly copying themselves through chemical reactions with their surroundings. There are plenty of organic compounds that are quite "tasty" for simple lifeforms even in abiotic environments (like Titan which, despite having no life we've detected, has literally oceans of hydrocarbons). Early life would subsist on the environment directly.
The structure of cells (including the cell wall/membrane separation and all organelles) likewise evolved separately from those simplistic ancestors.
By the time we get to multicellular life, there are already multiple avenues of energy consumption ranging from photosynthesis to consuming other cells to almost anything else you can imagine. Just look at the extremophiles we see today - there are organisms that live off of direct mineral consumption and heat from superheated thermal vents, bacteria that draw energy from the heat given off by radioactive decay far underground... Life is extremely varied.
The reasons the earliest forms of life branched off are simple as well - imperfect replication over many generations leads to larger changes. Populations of organisms in different geological locations will face different environmental selection pressures - "survival of the fittest" depends a great deal on where you are. As those populations in different environments continue to reproduce and mutate, their differences will increase. At this point, a common ancestor between animal and plant life, for example, is so far back that the changes in each population make them look almost completely different except under a microscope.
Remember also: evolution is not entirely random. Evolution does not happen to individuals, it happens to populations over time. Random mutation (which is still constrained to the possibilities of chemistry) is guided by the nonrandom process of natural selection, where the "fit enough" will survive to pass on their genes to the next generation. Given imperfectly replicating life forms and limited resources, the process of evolution is inevitable.
Does this help answer your questions?

This message is a reply to:
 Message 1 by godservant, posted 04-16-2008 11:34 AM godservant has not replied

  
Chiroptera
Inactive Member


Message 5 of 10 (463427)
04-16-2008 4:22 PM
Reply to: Message 1 by godservant
04-16-2008 11:34 AM


Herbivores would have needed appropriate digestive abilities to digest any available foliage currently available.
The reason that anything needs digestive systems is to bring food and nutrients to the cells. Single cells just take the nutrients from the environment, either taking in simple molecules or taking in more complex things (even other cells) and breaking them down.
Digestive systems are needed when the bodies become too large for the individual cells to take in the nutrients from the environment. So the first multicellular organisms were small until they could evolve simple transport systems where a few cells will take in the food and send it to the other -- look at sponges or jellyfish.
Then as the creature becomes more complex, so will the digestive system. They will become complex together.

Speaking personally, I find few things more awesome than contemplating this vast and majestic process of evolution, the ebb and flow of successive biotas through geological time. Creationists and others who cannot for ideological or religious reasons accept the fact of evolution miss out a great deal, and are left with a claustrophobic little universe in which nothing happens and nothing changes.
-- M. Alan Kazlev

This message is a reply to:
 Message 1 by godservant, posted 04-16-2008 11:34 AM godservant has not replied

  
molbiogirl
Member (Idle past 2641 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 6 of 10 (463694)
04-19-2008 2:52 AM
Reply to: Message 1 by godservant
04-16-2008 11:34 AM


When life sprang up, how did it remain in a constant state of balance between herbivores/carnivores/omnivores?
Whatever gave you the idea that there is some ideal state of "balance"?
Perhaps you can point me to evidence of this "balance".
Same beginning cells would have had to split at sometime to grow into plants as well as animals. both different cell make-up.
This seems OT.
You might want to post your questions about early evolution here:
Message 1.
If only herbivores existed in the beginning, what would be the benefit or possiblity (sic) of becoming carnivorous given plenty of foliage?
Whatever gave you the idea that there were only herbivores "in the beginning"?
Perhaps you can point me to evidence for this "herbivores-only" theory of yours.
Had each group had to evolve in order to obtain their respective characteristics to ensure survival, how did they survive to begin with?
Are you under the impression that a bunch of herbivores and a bunch of carnivores simply popped into existence and then somehow fought each other for resources until a magical balance was attained?
Really, now.

This message is a reply to:
 Message 1 by godservant, posted 04-16-2008 11:34 AM godservant has replied

Replies to this message:
 Message 7 by godservant, posted 04-19-2008 2:57 AM molbiogirl has replied

  
godservant
Junior Member (Idle past 5820 days)
Posts: 24
Joined: 04-15-2008


Message 7 of 10 (463695)
04-19-2008 2:57 AM
Reply to: Message 6 by molbiogirl
04-19-2008 2:52 AM


I'm just saying that they had to have started out feeding on something. If there was no foliage, then they would have had to eat eachother, if there was foliage and they ate that, what would be the purpose of eating eachother unless they ate all the foliage up??
Or did they just drink the cosmic soup they were created in? Kinda like a fetus drinking amniotic fluid??

This message is a reply to:
 Message 6 by molbiogirl, posted 04-19-2008 2:52 AM molbiogirl has replied

Replies to this message:
 Message 8 by molbiogirl, posted 04-19-2008 2:58 AM godservant has replied

  
molbiogirl
Member (Idle past 2641 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 8 of 10 (463696)
04-19-2008 2:58 AM
Reply to: Message 7 by godservant
04-19-2008 2:57 AM


Or did they just drink the cosmic soup they were created in? Kinda like a fetus drinking amniotic fluid??
Rahvin did a nice job explaining this.
Please read his answer carefully.

This message is a reply to:
 Message 7 by godservant, posted 04-19-2008 2:57 AM godservant has replied

Replies to this message:
 Message 9 by godservant, posted 04-19-2008 3:05 AM molbiogirl has replied

  
godservant
Junior Member (Idle past 5820 days)
Posts: 24
Joined: 04-15-2008


Message 9 of 10 (463697)
04-19-2008 3:05 AM
Reply to: Message 8 by molbiogirl
04-19-2008 2:58 AM


ok, so how many cell life forms happened to pop up when lightening hit that cosmic pool? Did they appear all in the same place? Was it just one in the beginning or many? The same or different? Isolated or in varied places? What are the chances the same cosmic soup was available all over the world for them all to appear when the lightening struck? (I'm being sarcastic about the lightening by the way)

This message is a reply to:
 Message 8 by molbiogirl, posted 04-19-2008 2:58 AM molbiogirl has replied

Replies to this message:
 Message 10 by molbiogirl, posted 04-19-2008 3:10 AM godservant has not replied

  
molbiogirl
Member (Idle past 2641 days)
Posts: 1909
From: MO
Joined: 06-06-2007


Message 10 of 10 (463699)
04-19-2008 3:10 AM
Reply to: Message 9 by godservant
04-19-2008 3:05 AM


ok, so how many cell life forms happened to pop up when lightening hit that cosmic pool?
This seems OT too.
Perhaps you'd like to post your questions here:
Message 1.
I strongly suggest you read the thread before posting.

This message is a reply to:
 Message 9 by godservant, posted 04-19-2008 3:05 AM godservant has not replied

  
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