1986; Musser et al., 1985; Selander, et al . 1986; Selander, 1985). Thus the 
assertion that genetic changes that occur in the laboratory are necessarily 
commonplace in nature does not hold (Stotzky and Babich, 1984). We do not 
know rates of genetic flux- -especially genetic rearrangements --in nature (let 
alone how natural selection operates on these changes). 
Of course, even if we do not know rates of change, there is no doubt that 
changes within genomes occur in nature. But, accepting the notion that such 
genomic changes regularly occur and using this idea to justify releases of 
engineered organisms are not the same. Two such justifications are standard. 
The first is the assertion that all prospective genetically engineered 
organisms exempted by the Working Group's proposition have already occurred, 
and therefore been "tested," in nature. This cannot be true. For example, it 
has been estimated that there are 10 atoms in the universe (Ayala and 
Valentine, 1979). Y^t, one organism, heterozygous at only 232 structural gene 
loci, can produce 10 kinds of gametes. Furthermore, the genotype of a 
released engineered organism does not fully predict the role the organism will 
play in the environment it is released into. As experience with introduced 
species attests, whether or not an organism is historically novel, it can 
produce novel consequences in a novel environment. Can we believe that any 
engineered organism covered by this proposition will already have been 
"tested" in all environments into which it might be released? One might then 
ask why new evolutionary adaptations ever occur! In addition, natural genetic 
changes occur in isolated individuals, but releases of engineered organisms 
will typically involve tremendous numbers of individuals. The ecological 
effects and viability of such large numbers of individuals may be entirely 
different than that of an isolated individual. Afterall, epidemiologists know 
that the spread of microbes depends on the size of source-pools, ecologists 
understand that many organisms are colonial because of the advantages of 
living in groups, and evolutionary biologists have established the existance 
of frequency dependent selection. 
The second justification for releases is to assert that since changes 
within a genome occur naturally, and extensive problems have not resulted from 
classical breeding programs (although there have been some (Colwell et al . , 
1985), the releases covered by the Working Group's proposition need no 
special scrutiny. However, just because an event can potentially occur in 
nature, does not mean that it should be freely promoted by humans; "natural" 
is not a justification just as "artificial" should not be a condemnation. 
For example, invasions of species into novel environments regularly occur in 
nature; otherwise volcanic islands would not have native faunas and floras, 
organisms would not currently be recolonizing Mount St. Helens, and much of 
the Northern hemisphere would not have been recolonized after the last glacial 
maximum. Yet, USDA wisely does not allow free introduction of organisms into 
this country. 
There is, however, some merit to the above assertion; one can use 
recombinant DNA techniques to accomplish more precisely genetic changes that 
could be made through classical techniques. And, on average . the risks of 
releasing organisms covered by this proposition are likely to be lower than 
the risks of releasing organisms altered with "foreign" DNA. Nevertheless, it 
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