What in your opinion most likely caused the Cambrian explosion?

[Hat]

I read a book called In the Blink of an Eye not long ago where the author claimed that the development of the eye is what led to the expansion of biodiversity. I've also heard the development of hard parts, changes in environment, and genetic causes.

 

I honestly don't have a feeling on this one. Do you? 

[verydeadthings]

The development of the eye seems very speculative and unlikely to me. I'm not aware of anything in the scientific literature supporting this. I'm a bit rusty on this, so take what I say with a grain of salt. There's clear evidence of complex multicellular metazoan life well before the Cambrian explosion, for example the Ediacaran fauna, extending perhaps past 1 billion years. The Cambrian explosion may be related to a rise in oxygen levels in the early Cambrian. Part of the Cambrian explosion may be taphonomic, that is, a lot of organisms developed hard parts like calcite which are more easily preserved (see http://www.nature.com/news/what-sparked-the-cambrian-explosion-1.19379). The interesting fundamental question here is whether the Cambrian explosion was a result of geologic/chemical changes in the ocean, or was a self-driven product of evolution reaching some tipping point with predation and ecosystem complexity, or genetic novelties like Hox genes.

[verydeadthings]

I may be too dismissive of Andrew Parker's book, considering I haven't read it. However, except in certain organisms like the trilobites, the eye is soft tissue, and not easily preserved. Also, primitive "eyes" are found in modern single-celled algae, and were probably present well before the Cambrian explosion.

[Ludwigia]

The first thing that came to me was also the rise in the oxygen levels, which is commonly stated as a proven fact, or at least extrapolation, in most literature on the subject.

[Hat]

10 hours ago, verydeadthings said:

I may be too dismissive of Andrew Parker's book, considering I haven't read it. However, except in certain organisms like the trilobites, the eye is soft tissue, and not easily preserved. Also, primitive "eyes" are found in modern single-celled algae, and were probably present well before the Cambrian explosion.

I don't recommend the book unless you're really really into the usage of optics in the animal kingdom... and the evolution of seed shrimp.

[ashcraft]

The Cambrian Explosion reeks of a mass extinction.  You have the sudden appearance of many new organisms in a very short time.  This happens after every extinction event.  The only thing missing is the original group of organism that held ecological superiority.  I suspect they were soft bodied, so didn't preserve well.

 

I am making an assumption that all of the niches were filled, and these cambrian organisms weren't expanding into newly created niches.

 

Name an instance where a mutation led an organism to rapid ecological superiority,  Dinosaurs with their fancy metabolism and lungs couldn't do it.  Mammals with their fancy mammary glands couldn't do it.  Flowering plants did, but that (in my opinion) is a special case, because in temperate regions, there is a great die-off of plants yearly, allowing for new growth.

 

Brent Ashcraft

[ynot]

In My opinion the cambrian explosion was the direct result of a lack of birth control devices!

[Kane]

lol @ynot!!!!

[Kane]

3 hours ago, ashcraft said:

 

 

Name an instance where a mutation led an organism to rapid ecological superiority,  

 

Brent Ashcraft

Various events, be them geological or climate-based, have resulted in the sudden introduction of invasive species that have taken pole position. In more recent, anthropogenic examples, international trade has led to to the rapid spread of Asian carp in North America, certain forms of ladybugs, earwigs during the colonial days, and the emerald ash borer. Attempts at cross-breeding, for example, resulted in the creation of the "killer bees" with considerable geographic spread. Zebra mussels are another example. 

 

By the Cambrian, with the geologically relative knock-on effects of sexual reproduction, increased genetic diversity seems to point to an increase in biodiversity as an almost competitive "arms race."

 

It very much depends if you hold to a first-wave ecological standpoint on systems (a la Odum brothers) that relies, in part, on cybernetics and discrete intervals that can be reasonably predicted. Experiments in this area were regrettably disastrous as any slight deviation would produce varying results from actual observation and the computer models. I don't know if we can reasonably assume without more evidence that all niches were filled, or if genetic surprise (evolution as spontaneous rather than adaptive, and only adaptive post hoc through selective trial and error) might have some impact here.

[Kane]

I should say that I more fancy the Prigogine and Stengers model of micro-instabilities leading to macro-stabilities, as it allows for more differentiality that is not indexed on dialectical negativity - i.e., I'm no Hegelian! Affirmative difference + increasing complexity would, in some ways defer or thwart the second law of thermodynamics. It is not that entropy is vitiated as inevitability, but there can be intervals of increased complexity and dynamism in multi-systems that can bypass that problem of Maxwell's demon, which entirely neglects a "governor's" role in a system to engage in forgetting - and thus in rushes true surprise in a Shannon sense of the term as truly informative as opposed to Wiener's dialectical opposition between information and entropy in systems. Despite that, we can still retain Wiener's nearly metaphysical view of information as being a "tritons genus" that is apart from physics' matter and energy, but that information can be configured differently.

 

Pure math offers some interesting examples when we consider the continuum hypothesis or the square root of two, but I think I've rambled enough 

[ashcraft]

4 hours ago, Kane said:

Various events, be them geological or climate-based, have resulted in the sudden introduction of invasive species that have taken pole position. In more recent, anthropogenic examples, international trade has led to to the rapid spread of Asian carp in North America, certain forms of ladybugs, earwigs during the colonial days, and the emerald ash borer. Attempts at cross-breeding, for example, resulted in the creation of the "killer bees" with considerable geographic spread. Zebra mussels are another example. 

 

By the Cambrian, with the geologically relative knock-on effects of sexual reproduction, increased genetic diversity seems to point to an increase in biodiversity as an almost competitive "arms race."

 

It very much depends if you hold to a first-wave ecological standpoint on systems (a la Odum brothers) that relies, in part, on cybernetics and discrete intervals that can be reasonably predicted. Experiments in this area were regrettably disastrous as any slight deviation would produce varying results from actual observation and the computer models. I don't know if we can reasonably assume without more evidence that all niches were filled, or if genetic surprise (evolution as spontaneous rather than adaptive, and only adaptive post hoc through selective trial and error) might have some impact here.

All ecological recoveries from mass extinctions are "arms races", as survivors try to maximise their piece of the ecological pie at all levels from individuals to orders.  I agree that if the niches weren't filled, (if you think a niche exists before it is occupied), then organisms, once capable, would have rapidly filled them.

 

However, life, selection pressure, and sexual reproduction had been around for millions, if not a billion years prior. Soft bodied organisms that exist today and wouldn't fossilize well are incredibly complex.   I think it is much more likely that unknown sort bodied organisms dominated the ecosystem, keeping what we consider "modern" organisms on the periphery, until an extinction event opened all the world up to the survivors.

 

Research will tell.

 

Brent Ashcraft

[doushantuo]

let me just say i posted something on the taphonomy of the Ediacaran,a while back.

so what goes into the diversity estimate,anyway?

Poriferan steranes?

Acritarchs?

SSF?

 

[doushantuo]

and has anyone read this?

[doushantuo]

this is fairly recent

 

[doushantuo]

fairly recent

[doushantuo]

recentest

[doushantuo]

canada

[doushantuo]

in line with Puffer(AJS,2002)*?(LIPs as possible causative agents)

*Pannotia breakup,Laurentian superplume)

[doushantuo]

I think a change in global linkages of the silica,iron,and phosphorus cycles MIGHT have something to with it(disproportionate Redfield ratios,etc)

Up to about 700 Mya ago,phosphorus burial on continental margins was low,much lower than it is today.

Funnily enough,i am not alone in this opinion(but what i'd really like to post here is heavily paywalled)

I think John Shergold was one of the first to invoke global phosphorous chemistry,back in the days

There's this spike in phosphatic microfossil abundance which might be significant 

So:increased scavenging of phosphorous in iron-rich oceans?