Deleterious mutations and the origin of the meiotic ploidy cycle

Article Abstract:

A theoretical analysis of a population genetic model in which the organism exists either as a haploid or alternates between diploid and haploid states, is presented. The analysis showed that haploidy is an evolutionarily stable state, while the alternating ploidy cylcle becomes evolutionarily stable only under certain circumstances. These circumstances involve the neccessity of a heterozygous condition to mask deleterious mutations, as well as a certain degree of recombination between a modifier locus and the locus under selection. These results indicate that the evolution of ploidy in eukaryotes first involved the reorganization of genes into more than one chromosome.

Evolution (Biology), Evolution, Ploidy

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RIPping and RAPping at berkeley

Article Abstract:

Specialists from the University of California at Berkeley discussed developments on the natural history of DNA. The phenomenon of repeat induced point mutation (RIP), an event where the eukaryotic genome seems to exhibit internal control, was discovered. The discovery followed DNA transformation of the Neurospora crassa sexual cycle. A variation of RIP involving an array of repeated sequences 220 bp was also studied. Some researchers suggested the term repeat associated point mutations to distinguish between the discussed phenomena.

Genetic polymorphisms, Letter to the Editor

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Heterozygote advantage and the evolution of a dominant diploid phase

Article Abstract:

A study was conducted to evaluate heterozygote advantage as a catalyst of a dominant diploid phase. A model is developed for the study's purpose. The model assumes that eukaryotic cells exhibit life cycles which are divided into haploid and diploid phases. The degree of phase dominance varies across species. Results show that heterozygote advantage does not influence the development of a dominant diploid phase in higher plants and animals.

Diploidy

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