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Author Topic:   Evolution - recent examples?
tubi417
Inactive Member


Message 1 of 39 (118424)
06-24-2004 8:52 PM


I've heard that evolution doesn't need a lot of time to occur. Are there any examples of evolution that have been observed by humans?
{Touched up title - Adminnemooseus}
This message has been edited by Adminnemooseus, 12-30-2004 21:48 AM

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


Message 2 of 39 (118451)
06-24-2004 10:19 PM


Thread moved here from the Proposed New Topics forum.

  
coffee_addict
Member (Idle past 477 days)
Posts: 3645
From: Indianapolis, IN
Joined: 03-29-2004


Message 3 of 39 (118459)
06-24-2004 10:58 PM
Reply to: Message 1 by tubi417
06-24-2004 8:52 PM


Yes.
Examples:
In laboratory experiments, people have observed bacterial cultures evolved to become anti-biotic resistant.
New species of plants arise all the time. Here is an article on speciation caused by polyploidy.
A new rat has also been found in Argentina that has twice the number of chromosomes as the normal rat. You can't find much on it right now because the species has only been discovered in (I think) 1998. Some believe that the rat came about because of an error in meiosis during reproduction of a normal rat probably 2 decades ago or so. There are some evidence that the rat is a lot more adaptive to the environment of the location than the normal rat. Keep your eyes open for future research on the rat.
Those are just some examples that came to my mind in 2 seconds.

The Laminator

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pink sasquatch
Member (Idle past 6023 days)
Posts: 1567
Joined: 06-10-2004


Message 4 of 39 (118468)
06-24-2004 11:21 PM
Reply to: Message 1 by tubi417
06-24-2004 8:52 PM


Here's one of my favorites, the study describes a single gene mutation leading to morphological and reproductive differences:
Evolution: single-gene speciation by left-right reversal.
Ueshima R, Asami T.
Nature. 2003 Oct 16;425(6959):679.
The researchers witnessed a speciation event in a closed population they were studying, a single gene mutation changed the shell pattern of a snail, and the constraints of the new shell shape prevent the snails with the two types of shells from aligning their genitals to mate. But, the old-shelled snails could mate with the old-shelled, and the new-shelled could mate with other new-shelled snails.
Thus snails with the shell-changing mutation are incapable of breeding with the ones without the mutation - even if they are sitting next to each other in the same pond. By most definitions this is considered speciation.
I think the snail example is powerful: Humans witnessed it, it is based on a single gene mutation, that mutation prevents mating between those with and without the mutation (reproductive isolation), and the shell pattern is visibly different (morphology difference).

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coffee_addict
Member (Idle past 477 days)
Posts: 3645
From: Indianapolis, IN
Joined: 03-29-2004


Message 5 of 39 (118471)
06-24-2004 11:30 PM
Reply to: Message 1 by tubi417
06-24-2004 8:52 PM


This is a preemptive strike against anyone that is going to argue that we haven't observed any "macro-evolution" (no, I'm not a Bush fan).
Micro and macro evolution are pretty much the same thing. The difference is that one happens over a short period of time and the other is just a combination of a whole bunch of the first one. Microevolution happens all the time. People observe it on a daily basis. A whole bunch of microevolution will result in what you would call macroevolution.
Some people on the board will deny that there is no difference, and I somewhat agree. To use crashfrog's example, microevolution is like taking a walk to the house next door and macroevolution is like taking a walk to the next town, the next state, or the next country. It will take you a long long time to get there, but you will eventually get there by walking.
So, no, we haven't seen any iguana growing wings and turn into a bird. Give us another few million years or so and I'll give you some examples of the so-called macroevolution.

The Laminator

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tubi417
Inactive Member


Message 6 of 39 (118473)
06-24-2004 11:36 PM
Reply to: Message 3 by coffee_addict
06-24-2004 10:58 PM


In laboratory experiments with antibiodics and bacteria, it isn't really evolution though. The bacteria are killed off that aren't resistant, but aren't the resistant bacteria usually much weaker than the bacteria that weren't resistant?
Someone explained it to me like this. Its sort of a weird way of looking at it, but just follow along. Say a new dictator (the antibiodic) comes to power. He orders everyone's left hand to be chopped off. So as hes chopping off everyone's left hand, he comes across 2 people who were born without a left hand. While everyone else bleeds to death, the 2 people without left hands survive and reproduce having more people without left hands. These people are naturally weaker though because they only have one hand.
Thats sort of like how an antibiodic works. It will attack something in the bacteria, but because some bacteria don't have what the antibiodic is attacking, they survive. because these surviving bacteria never had this thing the antibiodic was attacking, they are naturally much weaker compared to the rest of the bacteria without the antibiodic present.

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crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 7 of 39 (118475)
06-24-2004 11:39 PM
Reply to: Message 1 by tubi417
06-24-2004 8:52 PM


You might be interested in these links from Talkorigins. The first details a number of observed instances of speciation:
Observed Instances of Speciation
This second link details the evidence for "macro" evolution, which I think you're referring to:
29+ Evidences for Macroevolution: The Scientific Case for Common Descent
That's the best I can think of. These pages should have references to the literature, if you want to dig a little further. If you're interested in more scholarly material I suggest you search http://www.pubmed.org for abstracts.

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coffee_addict
Member (Idle past 477 days)
Posts: 3645
From: Indianapolis, IN
Joined: 03-29-2004


Message 8 of 39 (118481)
06-24-2004 11:45 PM
Reply to: Message 6 by tubi417
06-24-2004 11:36 PM


tubi417 writes:
In laboratory experiments with antibiodics and bacteria, it isn't really evolution though. The bacteria are killed off that aren't resistant, but aren't the resistant bacteria usually much weaker than the bacteria that weren't resistant?
Do you have a clue what evolution is?
The bacteria example IS an example of evolution. I'll give you a hint: survival of the fittest.

The Laminator

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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 9 of 39 (118487)
06-25-2004 12:00 AM
Reply to: Message 6 by tubi417
06-24-2004 11:36 PM


definitly weird
It sure is a weird way of looking at it.
Evolution works to allow a population to fit the environment of the time better. If the resitent bacteria are in an environment with the antibiotic, they are not "weaker" they are alive and the others aren't. If the enviroment then becomes one without the antibiotic then they are 'weaker' and will die out.
In the world of the hand chopping dictator the left handless are "better" than the two handed. Period, better. Doesn't say they are better in all environments just the one that they have evolved for.
It may be that almost any change also has some undesirable side effects. An organism survives based on the sum of all it's characteristics and the sum of all things about the environment.
It has been described as a "red queen race" -- from through the looking glass -- where you have to run as fast as you can to stay where you are.
If the environment stays with antibiotic in it the resistant bacteria are the "better" ones. Eventually there will be other mutations and these will not be good enough to survive and you'll find antibiotic resistant bacteria that are also better at handling something else as well. Will they be "stronger" than non antibiotic resistant ones?? Who cares if they are the best able to survive and are only in antibiotic environments.
Is this boy going to be "better" than anyone else?
http://12.31.13.113/healthnews/healthday/040623HD519696.htm
He has a mutation that produces stronger muscles than "normal"
At some things it seems he will be. Will he die of some complications early? Maybe. But it doesn't matter if his increased strength allows him to reproduce first and more than others. Will it allow him in our environment? Maybe not, maybe smarter would be better. Would it in other environments? Possibly.

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biochem_geek
Inactive Junior Member


Message 10 of 39 (118508)
06-25-2004 12:25 AM
Reply to: Message 6 by tubi417
06-24-2004 11:36 PM


I think that other people have accurately described how pulling out desirable traits from a variable population is actually a kind of evolution. There are however examples more like you seem to be looking for, new mutations leading to new traits for natural selection to act on:
Take, for example, the parasite that causes malaria
There is very little variation in the genepool of the parasite that causes malaria, probably because it is only about 10 000 years old as a species. Chloroquine has been used as an antimalrial drug since about the 1930s and worked for a very long time without any resistance, presumably because resistant parasites did not exist in the population.
So, in order to generate resistant parasites a new mutation will have to arise somewhere in the world. If this was to occur we would expect to see resistance to arise in one location and spread slowly across the world with the migration of people. This is exactly what happened, in the late 1950’s the first cases of chloroquine resistant malaria started showing up in Asia, but it took another 20 years to make it to Africa. Now it is hard to find a non-resistant malaria parasite in Africa, Asia or South America.
So there you have it, a novel and random mutation being favoured in a population by a selection within a human lifetime. Pubmed citation to a recent review on this and other malaria information

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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 11 of 39 (118627)
06-25-2004 10:27 AM
Reply to: Message 6 by tubi417
06-24-2004 11:36 PM


Someone explained it to me like this. Its sort of a weird way of looking at it, but just follow along. Say a new dictator (the antibiodic) comes to power. He orders everyone's left hand to be chopped off. So as hes chopping off everyone's left hand, he comes across 2 people who were born without a left hand. While everyone else bleeds to death, the 2 people without left hands survive and reproduce having more people without left hands. These people are naturally weaker though because they only have one hand.
The problem is that the anaology breaks down at the "These people are weaker" point.
They're alive. The others are dead. And who's weaker, again?

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Loudmouth
Inactive Member


Message 12 of 39 (118664)
06-25-2004 2:13 PM
Reply to: Message 6 by tubi417
06-24-2004 11:36 PM


quote:
In laboratory experiments with antibiodics and bacteria, it isn't really evolution though. The bacteria are killed off that aren't resistant, but aren't the resistant bacteria usually much weaker than the bacteria that weren't resistant?
Why are the antibiotic bacteria weaker? If they were weaker, then the antibiotic should have killed them off and the "stronger" bacteria should have survived. The mistake you are making is taking the bacteria out of the environment to which they are adapted. In the presence of antibiotic, the resistant bacteria are the strongest. It is within that environment that the bacteria evolved. It is like taking a fish out of water and claiming that all fish are weak.

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custard
Inactive Member


Message 13 of 39 (118843)
06-25-2004 8:04 PM
Reply to: Message 12 by Loudmouth
06-25-2004 2:13 PM


It is like taking a fish out of water and claiming that all fish are weak.
Great analogy.

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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 14 of 39 (118872)
06-25-2004 8:50 PM
Reply to: Message 6 by tubi417
06-24-2004 11:36 PM


Someone explained it to me like this. Its sort of a weird way of looking at it, but just follow along. Say a new dictator (the antibiodic) comes to power. He orders everyone's left hand to be chopped off. So as hes chopping off everyone's left hand, he comes across 2 people who were born without a left hand. While everyone else bleeds to death, the 2 people without left hands survive and reproduce having more people without left hands. These people are naturally weaker though because they only have one hand.
Amplifying on my earlier post:
Natural selection is concerned with the here-and-now. It selects the organisms that are best adapted to the environment today. "Weaker in some previous environment" doesn't matter. "Fitter in today's environment, right now" matters. And by that standard the people with no left hand are fitter.

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tubi417
Inactive Member


Message 15 of 39 (118923)
06-26-2004 12:31 AM
Reply to: Message 14 by JonF
06-25-2004 8:50 PM


well how would a new species some how be the result of that?

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