virus or prokatyotes - (Mar/10/2007 )
What is older, virus or prokaryotic cell?
Virus is more simple therefore easier to ‘be borne’ but how did it replicate then if there was no other organism?
I am convinced that prokaryotes were here first and some of them stuffed up.
Know there is endless discussion to it, but what people think?
Perhaps the answer is neither.
Perhaps prokaryotes and viruses (which are polyphyletic to begin with, and thus probably have varied histories) are contemporaries. Each has chosen a different line of development from the original LUCA (last universal common ancestor, which look probably was a population which swapped genes at some frequency.)
Much like saying who is ancestral, marsupials or placental. The answer we believe today is neither. They are contemporaries. The ancestral was probably an egg laying mammal.
And lastly, the viruses we see today are also highly evolved entities. One can easily imagine they are the only representive or even representives of only a single way of life that have survived to today.
Consider the lamprey and hagfish, both are parasitic scavengers, the last of the genre of jawless fish which once dominated the oceans of the world. Yet, if all jawless fish of today are parasitic, how can the jawless fish of yesterday ever be the dominant fish of the world? What would they parasitize upon?
Something is wrong.
This argument suffers the same problem with the virus argument. Fortunately we have fossil records to point out where. The jawless fish of yesterday weren’t all parasitic predators. They had a varied life style, probably from filter feeders, to active predators that crushed their prey with musculature alone (conjecture).
So just because only one way of life remains today, it doesn’t mean that it is the only means to survive. Conditions have changed greatly since the first prokaryote. And some viruses are truly strange. The mimi virus, which has a genome that is larger then smallest prokaryote, it even has DNA, RNA and the associated polymerase (both RNA and DNA).
Then there are viruses that can only replicated if a single cell is infected by several of the 8 viral isotypes… this strange “species” of virus has its genome parcel out to different viral particles. No every element arrives in one package.
But read this:
Key sentence: "The existence of several genes that are central to virus replication and structure, are shared by a broad variety of viruses but are missing from cellular genomes (virus hallmark genes) suggests the model of an ancient virus world, a flow of virus-specific genes that went uninterrupted from the precellular stage of life's evolution to this day."
But I'm not a virus expert