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Discussion Starter · #1 ·
BTW, speaking of Symbiogenesis, there seems to be a lot of literature that says Evolutionary progress and diversity has to be either Darwinian selection (competition and survival of the fittest) or Lynn Margulis' theory of Symbiogenesis (gaining ecological advantage through mutualism/cooperation) and that one is mutually exclusive of the other...

Any opinions to whether corals are the next step in symbiogenesis (starting with primitive cyanobacter infecting primitive eukaryotes) vs their potential as blatant competitors, in SPITE of the presence of Symbiodiniium spp.??? If so, how do we account for the azooxanthallate corals? Food chains in General? Just another ecological niche?
 

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I don't think that they are mutually exclusive at all.

A pair, triplet, etc can have just as good of an advantage as a single. Sometimes it takes a pair, etc to make it, sometimes not.

Sometimes being a pair or more can be a disadvantage.

I think you have a niche, that has certain parameters, and something will take advantage of it. For all practical purposes, corals have filled a niche that higher plants fill on land.
 

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Discussion Starter · #3 ·
My thoughts on the subject parallel this, why do you think that folks think that ist has to be one of the other? I would think that these are both means to the same end.

Well, there is that thing about some folks have to always be right, but then again, that has its own little niche for researchers... LOL!!!

:funny:
 

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Discussion Starter · #5 ·
ROTFLMAO!!!

Heh!!! It will come down to mutialism vs niche survival if the choice is clam "chowdah" heh heh heh!
 

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Discussion Starter · #6 ·
Hmmmmm... No Takers? Might have to start posting some literature ... :read: :read: :read: :read:
 

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I dunno this whole Marguli's thing smacks of liberial ideals laced with socialism ;)

Honestly though Tom I haven't had a chance to read her stuff in depth yet. I think right now folks are huddled up reading and waiting for someone to blink.
 

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BTW, speaking of Symbiogenesis, there seems to be a lot of literature that says Evolutionary progress and diversity has to be either Darwinian selection (competition and survival of the fittest) or Lynn Margulis' theory of Symbiogenesis (gaining ecological advantage through mutualism/cooperation) and that one is mutually exclusive of the other...

They certainly are not exclusive of each other as far as I can tell. The formation of symbioses are a perfect example of natural selection in favor of an organism(s).
 

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AND, it allows for a piggyback ride: if a host organism is selected, then the symbionts also usually get selected.

In fact, the formation of the symbioses may be a catalyst to evolution, which is what is on the minds of many biologists at the moment. Tom, you should see this right away, being so familiar with McConnaughey's hypothesis on Ca-proton exchange calcification.
 

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Your dating yourself here spanky.

Mmmmmm JP Morgan

" Your cheap, I admire that in a woman"!
 

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Discussion Starter · #14 · (Edited)
galleon said:
AND, it allows for a piggyback ride: if a host organism is selected, then the symbionts also usually get selected... ...In fact, the formation of the symbioses may be a catalyst to evolution, which is what is on the minds of many biologists at the moment...
Totally agree on this, I just don't see the logic behind someone deciding that it has to be one or the other, I think that there is a mutualism between these two theories... I personally think that the driving force behind exploitation of nich environments is via mutualisms and the true strength of them is what makes many organisms either adaptable or superior to the previous forms of that organism: and that this may be the real driving force behind Darwinism.

1st, second third levels of endosymbionts, so interesting that this occurs in something we like to study. I feel that this is the reason we still have corals after so many mass extinctions. Wonder if we can work Dr. Veron's work into this??? :D

...again, 0ne hand washes the other.
 

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they are both correct, one is an expansion of in incomplete theory
 

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Discussion Starter · #16 ·
In a related topic:

Coral Reefs
Publisher: Springer-Verlag Heidelberg
ISSN: 0722-4028
Issue: Volume 22, Number 2

Date: July 2003
Pages: 155 - 166
Species boundaries within the Acropora humilis species group (Cnidaria; Scleractinia): a morphological and molecular interpretation of evolution

J. K. Wolstenholme, C. C. Wallace, C. A. Chen

A1 Department of Marine Biology and Aquaculture, James Cook University, Townsville, Queensland 4811, Australia
A2 , Museum of Tropical Queensland, 78-102 Flinders St., Townsville, Queensland 4810, Australia
A3 , Institute of Zoology, Academia Sinica, Nankang, Taipei 115, Taiwan

Abstract:

Species boundaries remain unresolved in many scleractinian corals. In this study, we examine evolutionary boundaries of species in the Acropora humilis species group. Five morphologically discrete units are recognized using principal components and hierarchical cluster analyses of quantitative and qualitative characters, respectively. Maximum parsimony and likelihood analyses of partial 28S rDNA sequences suggest that these morphological units diverged to form two evolutionarily distinct lineages, with A. humilis and A. gemmifera in one lineage and A. digitifera and two morphological types of A. monticulosa in the other. Low levels of sequence divergence but distinct morphologies of A. humilis and A. gemmifera within the former lineage suggest recent divergence or ongoing hybridization between these species. Substantially higher levels of divergence within and between A. digitifera and A. monticulosa suggest a more ancient divergence between these species, with sequence types being shared through occasional introgression without disrupting morphological boundaries. These results suggest that morphology has evolved more rapidly than the 28S rDNA marker, and demonstrate the utility of using morphological and molecular characters as complementary tools for interpreting species boundaries in corals.

Keywords:

Acropora, Morphology, 28S rDNA, Species boundaries

The references of this article are secured to subscribers.
 

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Discussion Starter · #17 ·
OK... so no one's answerinnnnggg....

More bait...

Chloroplasts and mitochondria are organelles within eukaryotic cells (cells of organisms other than bacteria, which do not have organelles). These organelles have their own genetic material for replication and synthesis withing their membranes. The organelle's DNA is much more similar to bacteria than to nuclear DNA from the host eukaryotes. This evidence, combined with other events leading to new data finds, led researchers to the now widely held belief that these speciallized intracellular organelles were once free-living prokaryotic cells that began their symbiosis by living in proto-eukaryotic cells. This lead to the eventual required interdependance for these two organisms to live as one for existence. They became obligate endosymbionts, and although they are still linked by this reliance on each other for metabolic survival, it is noteworthy that these organelles still reproduce autonomously within eukaryotic cells.

A paper published in 1991 in Nature provided evidence for a double endosymbiotic event in cryptomonad algae. Although there had been some evidence for single endosymbiotic events in prokaryotic organisms, several new lines of evidence led researchers to conclude this double event had taken place. First, most chloroplasts are double-membraned (In the case of mitochondria, it is thought that one membrane comes from the protoeukaryotic cell, the second one from the endosymbiont bacteria). Chloroplasts from cryptomonad algae have more than two membranes. These chloroplasts contain a nucleomorph, a DNA-containing structure thought to be the vestigial remnant of a eukaryotic nucleus (in prokaryotes and intracellular organelles the DNA floats free).

The real surprise came when the researchers amplified regions of the 18S rRNA gene (using PCR). They discovered two different length sequences that they called Nu and Nm: Nu is believed to be from the nuclear DNA of the algae and Nm from the nucleomorph (they are still trying to get proof of this :D ) The two sequences are quite different; Nu is similar to nuclear DNA from amoeboid protozoans and Nm sequence is similar to red algae. The authors conclude that cryptomonad algae is a chimera of two endosymbiotic events. First a endosymbiotic event in which red algae was formed, then this eukaryotic red algae being taken into a protozoan creating the crytomonad algae.

see Douglas, et. al., Cryptomonad algae are evolutionary chimaeras of two phylogenetically distinct unicellular eukaryotes, Nature (1991), 350: 148-150.

Knowing that we have some organisms that demonstrate these double endosymbiotic events, is it possible that we are witness to a 3rd level of endosymbiosis when such organisms recruit Symbiodiniium spp.??? possibly a 4th or fifth??? Lets just suppose for a minute, that we are witness to a geological scale of time for a series of events. Rater than describe the chain of events, I will post a representation taken from Delwiche, C. F., 1999 in which he has traced the thread of plastid diversity through the tapestry of autotrophic life... (Am.Nat,1999, 154: pp5164-5177):

(test load)
 

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Master of Perplexity
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While I know I'm a slave to my genes, I'm still trying to figure out what evolutionary advantage they think having a reef tank will be? Whatever it is, I'll just go with it, cause it feels so good. On the other hand, there's the distinct possibility that this is all a conspiracy set up by the coral reef to preserve it's species!
"fleas that on him prey; And these have smaller still to bite em; And so proceed ad infinitum"
"It ain't what happens, it's what you do about it that counts!"
 
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