Natural Selection

Originally posted by twhitehead
I believe that dogs can breed with wolves, coyotes and jackals.

I would love to incorporate this fine sentence into some sort of creed.

Originally posted by twhitehead
I believe that dogs can breed with wolves, coyotes and jackals.

Do you know if the offspring are fertile? It wouldn't surprise me anyway, the distinction between a dog and a wolf comes down to whether it lives in the woods or is looked after by a person!

Originally posted by corp1131
Do you know if the offspring are fertile? It wouldn't surprise me anyway, the distinction between a dog and a wolf comes down to whether it lives in the woods or is looked after by a person!

Yes the offspring are fertile, and it is possible that dogs are more closely related to wolves than wolves are to coyotes. It would not supprise me if various other canines can breed with dogs as well. The definition of species is not as straight forward as it looks.

[edit]
Also have a look at this
http://en.wikipedia.org/wiki/Ring_species

Originally posted by micarr
DragonFriend look up this article on the late great evolutionary biologist Ernst Mayr who dedicated his life to answering the 'species problem': how could different species evolve from one common ancestor and as you say it is partly to do with geographic separation of isolates, please see on wiki and references therein 😉
http://en.wikipedia.org/wiki/Ernst_ ...[text shortened]... very nice site too
http://www.blackwellpublishing.com/ridley/a-z/Phyletic_gradualism.asp
...

Thanks. I'll check it out.

DF

Originally posted by scottishinnz
Best guess, essentially yes. There would be little selection benefit for specialising in the early evolution of life, although since there would have presumably been high rates of mutation (not so much of a problem for genetically 'simpler' organisms (or proto-organisms)) and little competition, huge variety could have arisen pretty early on. Indeed, ...[text shortened]... uced the number of 'flavours' of life down to a number of more genetically similar groups.

That explains some things and confused others.
Are you saying O2 was needed for early life to become multicellular?
I was under the impression that the initial O2 came from plants. Are there single celled plants that can produce O2?

DF

Originally posted by DragonFriend
That explains some things and confused others.
Are you saying O2 was needed for early life to become multicellular?
I was under the impression that the initial O2 came from plants. Are there single celled plants that can produce O2?

DF

The earliest life would have been prokaryotes, similar to todays blue-green algae. Single cellular photosynthetic organisms. What we'd understand as plants (i.e. terrestrial vascular plants, trees and the like) didn't evolve until around 400 million years ago - so relatively recently. Eukaryotic cells, like ours and 'plant' cells have a number of organelles, one of the most important being the mitochondrion, which like most of the other organelles is hypothesized to actually be a prokaryotic organism that got 'trapped' inside another cell. This had benefits for both, the mitochondrion was protected, and supplied with sugars etc, and the host cell had a really efficient way of producing energy. This is basically known as 'Endosymbiotic theory'. Generally eukaryotic cells (from which all multicellular life is comprised) require oxygen; it's just impossible to generate enough energy without the use of oxygen for multicellularity.
Around the so-called 'Cambrium explosion', 550 million years ago the atmospheric O2 concentration was only around 4%, but this was sufficient for multicellular life, although nothing big, and nothing fast / energetic. Once land plants came about, the global photosynthetic rate went up, and the O2 concentration of the atmosphere went up rapidly, upto roughly 30% during the Carboniferous (330 mya). AT this point there was plently of oxygen, which allows much more energy to be liberated, hence bigger, faster organisms could evolve. That's kind of the situation that we're currently in. Land plants were hugely important in terms of setting up the necessary conditions for large animal life, and key in the plants development was the evolution of a specialised type of water conducting cell called xylem. Without xylem land plants would never get above around 10cm tall, because water could not diffuse to their leaves quickly enough, and we'd never have evolved because the atmosphere would probably never get above 10% O2.

Originally posted by scottishinnz
The earliest life would have been prokaryotes, similar to todays blue-green algae. Single cellular photosynthetic organisms. What we'd understand as plants (i.e. terrestrial vascular plants, trees and the like) didn't evolve until around 400 million years ago - so relatively recently. Eukaryotic cells, like ours and 'plant' cells have a number of org ...[text shortened]... d never have evolved because the atmosphere would probably never get above 10% O2.

The earliest life would have been prokaryotes, similar to todays blue-green algae. Single cellular photosynthetic organisms.

How do you know this?

Do you have any evidence to suggest that it is possible for single cellular photosynthetic organisms to arise out of a 'chemical soup' by natural selection and random mutations only?

Originally posted by dj2becker
[b]The earliest life would have been prokaryotes, similar to todays blue-green algae. Single cellular photosynthetic organisms.

How do you know this?

Do you have any evidence to suggest that it is possible for single cellular photosynthetic organisms to arise out of a 'chemical soup' by natural selection and random mutations only?[/b]

fossils. 3.8 billion years old fossils. That coupled with the oxygen signal in those rocks, indicated by the oxidised Iron.

Oh, and you might want to look up Stromatolites - we have fossil stromatolites dated at 3.5 billion years old.


Do YOU, dj, have ANY empirical evidence of God whatsoever? If not, I'll accept my hypothesis (for which all the precursors are known to have existed) since it is more parsimonious.

Originally posted by scottishinnz
fossils. 3.8 billion years old fossils. That coupled with the oxygen signal in those rocks, indicated by the oxidised Iron.

What????

Do you have fossils of single cellular photosynthetic organisms that are 3.8 billion years old????

Hahahahahahaha!

😀😀😀😀😀😀😀😀😀

Originally posted by dj2becker
What????

Do you have fossils of single cellular photosynthetic organisms that are 3.8 billion years old????

Hahahahahahaha!

😀😀😀😀😀😀😀😀😀

Yes.

Originally posted by scottishinnz
fossils. 3.8 billion years old fossils. That coupled with the oxygen signal in those rocks, indicated by the oxidised Iron.

Oh, and you might want to look up Stromatolites - we have fossil stromatolites dated at 3.5 billion years old.


Do YOU, dj, have ANY empirical evidence of God whatsoever? If not, I'll accept my hypothesis (for which all the precursors are known to have existed) since it is more parsimonious.

Which dating technique did ya use?

Sigh. Here we go again...

Originally posted by dj2becker
Which dating technique did ya use?

Sigh. Here we go again...

Radiostrontium is the most frequently used.

Now, unless you are seriously thinking about trying to overturn the theory of relativity, I'd just leave this one alone.

Originally posted by scottishinnz
Radiostrontium is the most frequently used.

Now, unless you are seriously thinking about trying to overturn the theory of relativity, I'd just leave this one alone.

So you want me to take your word for it?

Surely you could supply a reference to some scholarly, peer-reviewed journal article on the subject?

Originally posted by dj2becker
So you want me to take your word for it?

Surely you could supply a reference to some scholarly, peer-reviewed journal article on the subject?

As if you would/could read it if he showed one to you.

LOL. You're such a goofball dj

Originally posted by telerion
As if you would/could read it if he showed one to you.

LOL. You're such a goofball dj

😛

I might surprise you.