Horizontal Gene Transfer: Evidence and Possible Consequences

摘要

The possibility that genetic information can move between remotely relatedspecies is an idea that has been strenuously resisted within traditional schools of biology. This is especially true of evolutionists who have developed neo-Darwinian theory. This resistance is natural, since superficially the concept seems at odds with the explanatory power of the phylogenetic tree in taxonomy and the important role of reproductive isolation as a mechanism of speciation. At the same time, progress in the field of molecular genetics over the past 25 years has led to many different observations consistent with horizontal gene transfers. It is not just that there are dozens of examples of likely horizontal transfers, but that the mechanisms which could accommodate horizontal transfer of DNA are observed everywhere. Multiple mechanisms for the physical transfer of DNA from one species to another are known. Recombination mechanisms that can absorb this DNA are ubiquitous. Examples of cells and organisms that will express and incorporate products from foreign genes are too numerous to list. Indeed, the concept of genetic coadaptation, which was a seriously accepted idea 10 years ago, is now rarely cited. Coadaptation posits that genes within a genome become so specifically coadapted with one another that they will fail to function with alternative alleles. The many cases of transgenic animals and cell lines created in vitro renders this idea obsolete. The only remaining question is whether the horizontal transfer of genes occurs at a rate that significantly influences evolution.