molbiogirl writes:
Now. Since Wright contends that 99.5% of all mutations are random and undirected, let's see you cite a paper that supports directed mutation in something other than a microorganism
I think we are on different wave lengths. I understand Shapiro as stating macro and micro evolution are 2 differenct entities and that maco is driven by directed mutations.
Shapiro "Mobile DNA and evolution in the 21st century" writes:
Although there remain many gaps in our knowledge, we are now in a position to outline a distinctively 21st century scenario for evolutionary change. The scenario includes the following elements:
(1) hereditary variation arises from the non-random action of built-in biochemical systems that mobilize DNA and carry out natural genetic engineering;
(2) major disruptions of an organism's ecology trigger cell and genome restructuring. The ecological disruptions can act directly, through stress on individuals, or indirectly, through changes in the biota that favour unusual interactions between individuals (cell fusions, interspecific hybridizations). Triggering events continue until a new ecology has emerged that is filled with organisms capable of utilizing the available resources;
(3) ecologically-triggered cell and genome restructurings produce organisms which, at some frequency, will possess novel adaptive features that suit the altered environment. Novel adaptive features can be complex from the beginning because they result from processes that operate on pre-existing functional systems, whose components can be amplified and rearranged in new combinations. Competition for resources (purifying selection) serves to eliminate those novel system architectures that are not functional in the new ecology;
(4) once ecological stability has been achieved, natural genetic engineering functions are silenced, the tempo of innovation abates, and microevolution can occur to fine-tune recent evolutionary inventions through successions of minor changes.
Another paper is a:
How Development Directs Evolution Epigenetics & Generative Ddynamics" Dr. Mae-Wan Ho
http://www.energysustainability.nl/mae-wan.pdf
Here are some exerpts.
Dr.Mae -Wan Ho writes:
Abstract and Introduction
In a paper published 30 years ago, Ho and Saunders (1979) proposed the then outrageous non-Darwinian idea that the intrinsic dynamics of developmental processes is the source of non-random variations that directs evolutionary change in the face of new environmental challenges; and the resulting evolutionary novelties are reinforced in successive generations through epigenetic mechanisms, independently of natural selection.
Our proposal has held up well against subsequent research findings, and is all the more relevant in view of the numerous molecular mechanisms discovered in epigenetic inheritance (Ho, 2009a,b) that could transmit developmental novelties to subsequent generations.
and later in the paper:
Ho writes:
Macroevolution therefore involves epigenetic and epigenetically directed genetic changes, and is decoupled from the random microevolutionary accumulation of base sequence changes.
and part of conclusion:
Ho writes:
What implications are there for evolution? Just as interaction and selection cannot be separated, nor are variation (or mutation) and selection, for the selective‟ regime may itself cause specific epigenetic variations or directed‟ mutations. The organism experiences its environment in one continuous nested process, adjusting and changing, leaving imprints in its epigenetic system, its genome as well as on the environment, all of which are passed on to subsequent generations. Thus, there is no separation between development and evolution. In that way, the organism actively participates in shaping its own development as well as the evolution of its ecological and social community. We do hold the future in our hands; it is precious, be careful.
Thus do Shapiro and HO see the future of evolution and both scientists do state a need for:
The OP in this thread "Does the Darwinian theory require modification or replacement?"
the answer that "micro evolution" may not direct mutations, but rather keeps organisms as they are and "macro evolution" directs the changes per Shapiro and Ho's theories.
molbiogirl writes:
Shadow.
It's simple.
Either cite Ho's published research or find another paper published in the research literature that supports your claim of directed mutation/directed evolution.
Shadow.
It's simple.
Either cite Ho's published research or find another paper published in the research literature that supports your claim of directed mutation/directed evolution.
You seem to lose perspective of the big picture, I am saying that evolution is directed in someway. It need not be mutational direction.
Clearly the above cilted writings of experts in the field are saying that there is more to evolution than random mutation and natural selection.
When you look at the research in these discplines:
Evolvability
Epigenesis
Phenotypic plasticity
evolutionary development (evo-devo)
reticulat evolution
endosymbiiosis and symbiogenesis
horizoontal gene tansfer
You have to at least acknowledge that the current theory of evolution is not complete, and may need change.
So direction is most probably above the micro level and in the macro level as many papers are now stating.
Please remember the OP is DOES THE DARWINIAN THEORY REQUIRE MODIFICATION OR REPLACEMENT.
You cannot ignore all of the papers out there that say yes, and just say Shadow, show me mutation at the eukaroytic level that is directed.
It is way above that level as the papers state.
There are clearly papers that favor the positon that evolution to some extent is directed.
Edited by shadow71, : No reason given.
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