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HalfMooner
Dingaling
Philippines
15831 Posts |
 Posted - 01/05/2009 : 16:19:55
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This article is from Science Daily: Longstanding Theory Of Origin Of Species In Oceans Challenged
ScienceDaily (Jan. 1, 2009) — New evidence uncovered by oceanographers challenges one of the most long-standing theories about how species evolve in the oceans.
Most scientists believe that allopatric speciation, where different species arise from an ancestral species only after breeding populations have become physically isolated from each other, is the dominant mode of speciation both on land and in the sea. The key to this theory is the existence of some kind of physical barrier that operates to restrict interbreeding (gene flow) between populations so that, given enough time, such populations diverge until they're considered separate species.
For example, finches that were blown by storms from South America to the Galapagos Islands (and were studied by Charles Darwin) were consequently isolated from their host populations and these isolated breeding colonies evolved separately from each other until they became separate species.
Research by Dr Philip Sexton formerly of the National Oceanography Centre, Southampton (now at the Scripps Institution of Oceanography, San Diego) and Dr Richard Norris (also of Scripps) suggests, however, that this mode of diversification may not be as prevalent for oceanic creatures as it is for land dwellers and somewhat controversially, they assert that the above model of speciation may actually be very rare in the world's oceans. |
In its potential to change evolutionary theory, I think it's possible that this new research may create as great a "paradigm shift" as neo-Darwinism itself was to evolution.
Note that this is not the knock-out blow to evolution for which Creationists might dream, but rather a major challenge to the previously understood methods of evolution in the oceans. (In this study, the role of population isolation in ocean life speciation is seen as vastly reduced compared to the standard accepted model.) Even if this latest proves wrong, this kind of research shows just how (unlike fundamental religionists) scientists are not shackled by dogma, and just how willing they are to revolutionize their thinking in order to find the truth.
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
Edited by - HalfMooner on 01/05/2009 16:58:33
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H. Humbert
SFN Die Hard
USA
4574 Posts |
Posted - 01/05/2009 : 17:37:12 [Permalink]
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Originally posted by HalfMooner
The key to this theory is the existence of some kind of physical barrier that operates to restrict interbreeding (gene flow) between populations so that, given enough time, such populations diverge until they're considered separate species. |
From everything I've ever heard, it's enough that breeding populations are sufficiently distanced from one another, not that a physical barrier must exist to prevent it.
For instance, I remember hearing the following example. Population A forages and breeds in close proximity to Population B, with which they can also interbreed. Population B forages and breeds in close proximity to Population C, with which they can interbreed as well. But given enough time, Population A might not be able to interbreed with Population C, and thus could give rise to a new species.
So sheer physical distance seems enough of a "barrier" to allow for speciation to occur, which is how I assumed it worked for most ocean-based life. At least, the ones that couldn't navigate vast distances.
So I don't find this article all that radical, but expect creationists to quote mine it anyway.
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"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
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HalfMooner
Dingaling
Philippines
15831 Posts |
Posted - 01/05/2009 : 18:49:10 [Permalink]
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Originally posted by H. Humbert
So I don't find this article all that radical, but expect creationists to quote mine it anyway. |
Right. Starting with the title, of course. Maybe ending there, even.
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
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Kil
Evil Skeptic
USA
13477 Posts |
Posted - 01/05/2009 : 19:27:54 [Permalink]
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Timeline of evolution
The basic timeline is a 4.6 billion year old Earth, with (very approximate) dates:
* 3.8 billion years of simple cells (prokaryotes),
* 3 billion years of photosynthesis,
* 2 billion years of complex cells (eukaryotes),
* 1 billion years of multicellular life,
* 600 million years of simple animals,
* 570 million years of arthropods (ancestors of insects, arachnids and crustaceans)
* 550 million years of complex animals
* 500 million years of fish and proto-amphibians,
* 475 million years of land plants,
* 400 million years of insects and seeds,
* 360 million years of amphibians,
* 300 million years of reptiles
* 200 million years of mammals,
* 150 million years of birds,
* 130 million years of flowers,
* 65 million years since the non-avian dinosaurs died out,
* 2.5 million years since the appearance of the genus Homo,
* 200,000 years since humans started looking like they do today,
* 25,000 years since Neanderthals died out. |
Land plants don't appear until 475 million years ago. The timeline starts at 3.8 billion years ago. According to this timeline, life has spent most of its time in water, and only recently (geologically speaking) spreads to land.
That's more than 3 billion years of evolution in the water only and 1.8 billion years before complex cells appear.
You would think that would be time enough even without solid physical barriers, given that such things as currents, depth, water temperature and other factors varies greatly from place to place and surly did 3.8 billion years ago too. Speciation really could have been a rare event in the oceans (when compared to land) and still would have had plenty of time to get the job done.
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Uncertainty may make you uncomfortable. Certainty makes you ridiculous.
Why not question something for a change?
Genetic Literacy Project |
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Dr. Mabuse
Septic Fiend
Sweden
9688 Posts |
Posted - 01/06/2009 : 03:01:35 [Permalink]
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Originally posted by H. Humbert
Originally posted by HalfMooner
The key to this theory is the existence of some kind of physical barrier that operates to restrict interbreeding (gene flow) between populations so that, given enough time, such populations diverge until they're considered separate species. |
From everything I've ever heard, it's enough that breeding populations are sufficiently distanced from one another, not that a physical barrier must exist to prevent it.
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Ring Species.
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Dr. Mabuse - "When the going gets tough, the tough get Duct-tape..."
Dr. Mabuse whisper.mp3
"Equivocation is not just a job, for a creationist it's a way of life..." Dr. Mabuse
Support American Troops in Iraq:
Send them unarmed civilians for target practice..
Collateralmurder. |
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Theory Of Origin Of Species In Oceans Challenged
