Macromutations Yielding Karyotype Alterations (and the Process(es) behind Them) Are the Favored Route of Carcinogenesis and Speciation.

It is argued that carcinogenesis and speciation are evolutionary events which are based on changes in the 'karyotypic code' through a phase of 'genome instability', followed by a bottleneck of selection for the viability and adaptability of the initial cells. Genomic (i.e., chromosomal) instability is caused by (massive) DNA breakage and the subsequent mis-repair of DNA double-strand breaks (DSBs) resulting in various chromosome rearrangements. Potential tumor cells are selected for rapid somatic proliferation. Cells eventually yielding a novel species need not only to be viable and proliferation proficient, but also to have a balanced genome which, after passing meiosis as another bottleneck and fusing with an identical gamete, can result in a well-adapted organism. Such new organisms should be genetically or geographically isolated from the ancestral population and possess or develop an at least partial sexual barrier.