Saturday, 14 May 2016

Evolving a Loss of Complexity!

Monocercomonoides
First eukaryotes found without a normal cellular power supply | Science | AAAS

One of the problems creationism suffers from, apart from not having any supporting evidence, is that it relies almost entirely on dogma. One such dogma, for example, is that scientists believe evolution is all about life progressing from the simple to the complex and that somehow all evolutionary change must involve an increase in complexity.

Yes, I know this is nonsensical and at odds with the facts, but that's the point of dogma; it means evidence doesn't need to be bothered with because the truth is 'known' by fiat. The dogma says so...

What this dogma is for, and probably the reason it's clung to with such tenacity, is so creationists can cite yet another dogma - that new information can't arise because of the Second Law of Thermodynamic (sic) so increasing complexity, which so it is assumed, involves new information, is impossible. Two pieces of dogma with no supporting evidence and which run counter to the actual evidence. But this enables creationist frauds to construct what looks to the scientifically illiterate people they are duping like a logical, scientific argument, even involving real science like the Second Law, albeit misrepresented and misapplied.

But, what about parasites, particularly endoparasites where evolution almost always leads to a loss of complexity - Parasitic worms, for example, which have lost their digestive tracts and simply absorb nutrients directly through their skins from their host?

Now here we have an example which may be the first example of a complex (eukaryote) cell losing what were thought to be an essential organelle for a eukaryote cell - their mitochondria. Mitochondria are the powerhouses of a complex cell, building ATP from ADP and phosphate. They also have another function. They produce small clusters of iron and sulphur which form prosthetic groups for some proteins.

Mitochondria are the descendants of bacteria which formed a symbiotic relationship with other prokaryote cells to form the eukaryote cells from which all multicellular organisms are made. They have retained at least some of their own DNA and replicate independently within the cell, so forming their own evolutionary tree. Some organisms are known to have transferred some mitochondrial DNA into the cell nucleus. However, this organism, known to science as as member of the Monocercomonoides genus seems to have lost its mitochondria altogether. Some close relatives have very much reduced mitochondria but this is the first which seems to have dispensed with them altogether.

This particular species inhabits a highly specialised environment, being found only in the gut of the chinchilla. The team from Charles University in Prague, led by Anna Karnkowska, sequenced the genome of this Monocercomonoides and found no trace of mitochondrial DNA.

Highlights
  • Monocercomonoides sp. is a eukaryotic microorganism with no mitochondria
  • The complete absence of mitochondria is a secondary loss, not an ancestral feature
  • The essential mitochondrial ISC pathway was replaced by a bacterial SUF system

Summary
The presence of mitochondria and related organelles in every studied eukaryote supports the view that mitochondria are essential cellular components. Here, we report the genome sequence of a microbial eukaryote, the oxymonad Monocercomonoides sp., which revealed that this organism lacks all hallmark mitochondrial proteins. Crucially, the mitochondrial iron-sulfur cluster assembly pathway, thought to be conserved in virtually all eukaryotic cells, has been replaced by a cytosolic sulfur mobilization system (SUF) acquired by lateral gene transfer from bacteria. In the context of eukaryotic phylogeny, our data suggest that Monocercomonoides is not primitively amitochondrial but has lost the mitochondrion secondarily. This is the first example of a eukaryote lacking any form of a mitochondrion, demonstrating that this organelle is not absolutely essential for the viability of a eukaryotic cell.

Karnkowska, Anna et al.
A Eukaryote without a Mitochondrial Organelle
Current Biology
, Volume 0 , Issue 0 DOI: http://dx.doi.org/10.1016/j.cub.2016.03.053


The organism seems to have replaced the normal mitochondrial energy production function and now uses enzymes in the cell cytoplasm to release energy from nutrients, possible because although the chinchilla gut is high in nutrients, it is low in the oxygen normally needed for mitochondrial function.

In another interesting twist, the iron and sulphur cluster production seems to have been replaced by acquired bacterial genes.

So, here we have an example of evolution in a highly specialised environment resulting in a radical reduction in complexity amounting to the loss of an entire cell organelle together with its entire genome. This is an interesting but fully explainable discovery for biology; it is a massive refutation of one of creationism central dogmas. Evolution has occurred by a loss of complexity and a loss of information.

Would a creationist like to explain this and say how creationism will be revising its dogma, or will it continue to be based on necessity not facts?

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