Open Access Pub publishes peer-reviewed, free-to-read open-access articles. Showing
articles matching Darwinian selection — open any to read the full text,
or download the PDF or XML.
A new type of mutations-dominant lethals with a facultative manifestation -were discovered in D. melanogaster in 2000. These mutations were named conditional mutations. Under restrictive genetic conditions, the mutations manifest themselves as dominant lethals, whereas dominant lethality disappears under permissive conditions, displaying a set of other manifestations. The genes responsible for the emergence of conditional mutations were named ontogenes. The experiments with mutations in ontogenes have revealed the following processes: (1) genome editing in germline cells; (2) induction of high mutagenesis rates in germline cells of the mutants for ontogenes; (3) zygotic selection; (4) isolation of mutants; and (5) alterations in the lethality of mutants with time. The specific features in the manifestation of ontogenes together with the listed processes formed the background for construction of the model of speciation named the regeneration model. The event of speciation is represented as the regeneration of the working state of a genetic system disturbed by the emergence of a mutation in an ontogene. According to the model, it is ontogenes that are in charge of speciation and, eventually, the structure of living matter in the form of individual species. The significance of Mendelian protein-coding genes and Darwinian selection of the fittest according to these genes are doubtless but not paramount.
F Chadov BorisCorresponding author Institute of Cytology and Genetics, Siberian Department of Russian Academy of Sciences, Novosibirsk 630090, Russian Federation.
The existing hypotheses on speciation rely on Mendelian genes and mutations in them. However, genome-wide sequencing demonstrates that the Mendelian genes account less than one-tenth of the entire genome DNA. This means that a greater part of the genome has not yet been subject to large-scale evolutionary consideration. This paper deals with the conditional mutations in drosophila, which are mutations of the genes belonging to a special category (ontogenes) controlling the program of individual development. The ontogenes presumably reside in the DNA of intergenic spaces and introns. Conditional mutations display a number of properties absent in the mutations of Mendelian genes. These specific properties allow three key problems in speciation to be solved: (1) the possibility of emergence of new traits as a result of sequential mutagenesis; (2) selection of mutants; and (3) establishment of isolation. We have shown that (1) the mutations in ontogenes are able to form new multigenic regulatory blocks that escape selection during their creation; (2) mutations in ontogenes allow for existence of constantly acting zygotic selection, which is by no means less important for speciation than Darwinian selection; and (3) owing to their conditionally lethal effect, the mutations in ontogenes are able to create biological isolation barrier. This gives the grounds for assuming that the emergence of mutations in ontogenes is a necessary condition for speciation.