Darwin re-visited

[Michaelangelica]

Over 20 years ago, Jeff Wyles, Allan Wilson, and Joseph Kunkel proposed that big brains might favor adaptive evolutionary diversification in animals by facilitating the behavioral changes needed to use new resources or environments, a theory known as the behavioral drive hypothesis. . . .

animals with larger brains, relative to their body size, have more developed skills for changing their behavior through learning and innovation, facilitating the invasion of novel environments and the use of novel resources. Despite the progress, the role of the brain in the adaptive diversification of animals has remained controversial, mostly due to the difficulties to demonstrate that big-brained animals evolve faster.

"The most likely alternative," Daniel Sol states, "is that big brains enhance the rate of evolutionary diversification by facilitating changes in behavior, which would place new selection pressures on populations and favor adaptive divergence." Thus, in species with high cognitive styles, behavior might be, along with environmental factors, a major driving force for evolution.

Big-brained Animals Evolve Faster

[HydrogenBond]

There was a study done that took an Ecoli that thrived in a specific environment. The scientist then transferred the bacteria to an environment where the Ecoli would not thrive; there was a rapid decrease in the population of Ecoli at first. But then after 33,127 generations of the Ecoli living in this new environment it formed 10 to 20 good mutations and actually had a huge increase in population allowing it to survive in this new environment.

 

There was similar experiment where they removed a gene used to produce a lactate digesting enzyme. Within very few generations the bacteria modified another gene and were back in business. They then remove that modified gene also, and it too much much longer.

 

Both experiments suggest cause and affect, where the environmental cause will induce a logical genetic affect. The random assumption is due to the limitation of the existing theory. It is an empirical way to get a result when logic is lacking.

 

One way to prove this is to do the first experiment again. But this time compare the rate of mutations, both useful and useless, as a function of time, to a standard sample with a controlled or optimized environment. If the environment is pushing the genetics the tweaked sample should show more genetic activity in terms of trying to change. In other words, the genetic modification to the new environment will not just spontaneously appear in the controlled sample at the same rate.

 

A simpler experiment is have a control sample and an environmentally modified sample. At the end, when there is adaptation in the dynamic sample, compare to see if the control sample had the same probability of change in terms of this new gene. I bet the effect is cause and affect based relative to the environmental stress.

[Galapagos]

There was similar experiment where they removed a gene used to produce a lactate digesting enzyme. Within very few generations the bacteria modified another gene and were back in business. They then remove that modified gene also, and it too much much longer.

 

Both experiments suggest cause and affect, where the environmental cause will induce a logical genetic affect. The random assumption is due to the limitation of the existing theory. It is an empirical way to get a result when logic is lacking.

Lenski's experiment suggests a historical contingency on previous mutations in the particular population. There were billions of mutations before the innovative one occurred, but the fact that it occurred in all 12 colonies after a similar number of generations(and potentiating mutation) indicates a historical contingency.

http://myxo.css.msu.edu/lenski/pdf/2008,%20PNAS,%20Blount%20et%20al.pdf

The role of historical contingency in evolution has been much debated, but rarely tested. Twelve initially identical populations of Escherichia coli were founded in 1988 to investigate this issue. They have since evolved in a glucose-limited medium that also contains citrate, which E. coli cannot use as a carbon source under oxic conditions. No population evolved the capacity to exploit citrate for >30,000 generations, although each population tested billions of mutations. A citrate-using (Cit+) variant finally evolved in one population by 31,500 generations, causing an increase in population size and diversity. The long-delayed and unique evolution of this function might indicate the involvement of some extremely rare mutation. Alternately, it may involve an ordinary mutation, but one whose physical occurrence or phenotypic expression is contingent on prior mutations in that population. We tested these hypotheses in experiments that “replayed” evolution from different points in that population's history. We observed no Cit+ mutants among 8.4 × 1012 ancestral cells, nor among 9 × 1012 cells from 60 clones sampled in the first 15,000 generations. However, we observed a significantly greater tendency for later clones to evolve Cit+, indicating that some potentiating mutation arose by 20,000 generations. This potentiating change increased the mutation rate to Cit+ but did not cause generalized hypermutability. Thus, the evolution of this phenotype was contingent on the particular history of that population. More generally, we suggest that historical contingency is especially important when it facilitates the evolution of key innovations that are not easily evolved by gradual, cumulative selection.

 

This article perfectly demonstrated natural selection working in a lab setting, and the prevailing theory gave Lenski the appropriate framework in which to make predictions. I'm not sure what sort of logic is supposed to be lacking here; it seems as though Lenski and his team did some great science, and settled a theoretical dispute in the field(S J Gould's claims about "replaying the tape of life").

[Michaelangelica]

I know this is relevant.

It is just a great pity that I don't understand it:(

 

Did evolution come before life?

Did evolution come before life? - life - 15 September 2008 - New Scientist

[Galapagos]

Evolutionary biologist Richard Dawkins released a three part series entitled "The Genius of Charles Darwin" around a month ago. It is educational, informative, provocative, and entertaining. I highly recommend it to all Hypography readers!

 

Richard Dawkins: The Genius of Charles Darwin (Episode 1 of 3) http://video.google.com/videoplay?docid=-4471435322910215458&ei=ZmbUSK-5K4mwrQLw_oy_Ag&q=genius+of+darwin

The Genius of Charles Darwin - The Fifth Ape http://video.google.com/videoplay?docid=4491999408234054262&hl=en

Evolution – Richard Dawkins – “Genius of Darwin” (Part 3) http://video.google.com/videoplay?docid=4186124484673756877&ei=ZmbUSK-5K4mwrQLw_oy_Ag&q=genius+of+darwin

[Moontanman]

I know this is relevant.

It is just a great pity that I don't understand it:(

 

This is the premise of my thread "Life as we know it" I feel very strongly that Life as we know it is a small subset of the possible ways the Earth could have gone and that the Earth was at one time alive in a way that now only a single cell qualifies as alive.

 

http://hypography.com/forums/biology/15781-life-as-we-know-it.html

[Michaelangelica]

Professor Julian Saulescu

Enough Rope with Andrew Denton - ABC TV - 'Everyone has a story'

 

video.

[Shieldage]

I believe the correct qualification is:

 

"Survival of the fittest... at the moment."

 

As far as I can tell the dinosaurs didn't die out because they were necessarily unfit, and small mammals were fitter, they just died because the Earth changed over a period of time.

 

Take mammals during the Ice Age. Many species adapted and adapted, growing long fur and gaining weight. When the Ice Age ended, plenty died out, because while the species that hadn't changed overly may have viewed it as return to 'normal' climate patterns, many of those that had changed with the Ice Age reacted to the rise in temperatures as a massive detrimental climate shift.

 

Right?

[Moontanman]

I believe the correct qualification is:

 

"Survival of the fittest... at the moment."

 

As far as I can tell the dinosaurs didn't die out because they were necessarily unfit, and small mammals were fitter, they just died because the Earth changed over a period of time.

 

Take mammals during the Ice Age. Many species adapted and adapted, growing long fur and gaining weight. When the Ice Age ended, plenty died out, because while the species that hadn't changed overly may have viewed it as return to 'normal' climate patterns, many of those that had changed with the Ice Age reacted to the rise in temperatures as a massive detrimental climate shift.

 

Right?

 

The demise of the dinosaurs is thought to have been rather quick as in the result of the impact of a ten mile wide asteroid or comet. Mammals weren't any more fit than dinosaurs as much as they were simply small, small reptiles, amphibians, and birds also survived. but you are correct in that climactic changes often result in the extinction of animals that cannot change fast enough. During the last ice age humans probably helped many large animals to the grave they simply couldn't change their habits fast enough to to adapt to the presence of humans.

[Pyrotex]

I believe the correct qualification is:

"Survival of the fittest... at the moment."...

You have made an excellent point.

I have always taken for granted that "survival of the fittest" reflected fitness for the current environment at THIS moment, and then THIS moment...etc.

You've pointed out that someone might assume that it reflected inherent fitness. Though that would ALSO be appropriate (a race of short-legged tigers would soon starve, right?) -- Darwin's original intention was as you said it: survival of the fittest at the moment.

 

Except the dinosaurs. :) :doh: ;) ;)

 

There must be a thousand jokes out there "explaining" the extinction of the dinosaurs. My favorite is still the "theory" that they took up smoking cigarettes.

[REASON]

There must be a thousand jokes out there "explaining" the extinction of the dinosaurs. My favorite is still the "theory" that they took up smoking cigarettes.

 

That would be the theory of the famous cartoonist Gary Larson, creator of The Far Side :)

[Moontanman]

That would be the theory of the famous cartoonist Gary Larson, creator of The Far Side :)

 

The Far Side is one of the top five best humor of all time.

[Thunderbird]

One aspect of evolution that has fascinated me is the survival of the adaptive cycle. Birds as an example are very highly adaptive because their migratory paths are so far ranging as to offset any changes in environment.

The migratory path of say a population of Triceratops or duckbills could be devastated in short order by drought in the feeding ground or a flood in the breeding area, where birds may have optional seasonal ground for feeding and breeding.

[Michaelangelica]

One aspect of evolution that has fascinated me is the survival of the adaptive cycle. Birds as an example are very highly adaptive because their migratory paths are so far ranging as to offset any changes in environment.

The migratory path of say a population of Triceratops or duckbills could be devastated in short order by drought in the feeding ground or a flood in the breeding area, where birds may have optional seasonal ground for feeding and breeding.

Fish migrate too.

older bigger fish taech younger fish in schools

When we eat the big fish, the little fish get lost :)

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Does anyone know if mitochondrial DNA is the same in maternal-(monozygotic) twins

How Can Identical Twins Be Genetically Different?

Identical Twins Identical Problems -- Scientists Discover New Genes Linked To Rheumatoid Arthritis

There seems to be a big assumption that twins are 100% the same, which ignores epigenetic factors.

[Michaelangelica]

One aspect of evolution that has fascinated me is the survival of the adaptive cycle. Birds as an example are very highly adaptive because their migratory paths are so far ranging as to offset any changes in environment.

The migratory path of say a population of Triceratops or duckbills could be devastated in short order by drought in the feeding ground or a flood in the breeding area, where birds may have optional seasonal ground for feeding and breeding.

Fish migrate too.

Older, bigger fish teach younger fish in schools

When we eat the big fish, the little fish get lost :)

---------------------------------------------------------------------------

 

Does anyone know if mitochondrial DNA is the same in maternal-(monozygotic) twins?

How Can Identical Twins Be Genetically Different?

Identical Twins Identical Problems -- Scientists Discover New Genes Linked To Rheumatoid Arthritis

There seems to be a big assumption that twins are 100% the same, which ignores epigenetic factors.

[Pyrotex]

...When we eat the big fish, the little fish get lost :Exclamati

Yeah. The little fish drop out of school.

They never learn about "getting hooked".

[Michaelangelica]

Yeah. The little fish drop out of school.

They never learn about "getting hooked".

It may sound like a joke, but it is true.

The Law here, prevents you from taking undersised fish (specified for each variety). So only the big guys- with the knowledge- go into the frying pan or Sushi Shop.

No one knows enough about this, and what species are effected/affected most.

It could be disastrous for deep-sea, long-lived (30- ?+ years) Orange Roughy for example from above Antarctica off the Oz coast.

This was a real gold rush when Orange Roughy were first found, and within a few short years they were on the endangered list.

 

My Dad used to say "You/He/They are like a bull in a China Shop". It seems to me that's exactly how humans are behaving on this planet.

We know so little about Earth's ecology etc., etc., that it is frightening.