New Perspectives on the Evolution of Within-Individual Genome Variation and Germline/Soma Distinction

Abstract

Genomes can vary significantly even within the same individual. The underlying mechanisms are manifold, ranging from somatic mutation and recombination, development-associated ploidy changes and genetic bottlenecks, over to programmed DNA elimination during germline/soma differentiation. In this perspective piece, we briefly review recent developments in the study of within-individual genome variation in eukaryotes and prokaryotes. We highlight an SMBE 2020 virtual symposium entitled “Within-individual genome variation and germline/soma distinction” and the present Special Section of the same name in Genome Biology and Evolution, together fostering cross-taxon synergies in the field to identify and tackle key open questions in the understanding of within-individual genome variation.

Foraminifera as a model of the extensive variability in genome dynamics among eukaryotes

“…Wang & Davis 2014 [4] ; Suh & Dion-Côté 2021 [89] Phytophthora Stramenopile This genus, which includes the causative agent of the potato blight during Ireland's Great Famine, is frequently found with aneuploid regions of chromosomes. The mechanisms and implications of this aneuploidy are yet poorly understood.…”

Rapid gene content turnover on the germline-restricted chromosome in songbirds

“…In multicellular organisms, all cells of an individual normally contain the same genetic information. There are exceptions, however, where certain sequences are eliminated from all or some of the somatic cells during development, leaving the original genetic information to be maintained in the germ cells 1 , 2 . An interesting example of this programmed DNA elimination has been described in songbirds, where a whole chromosome is lost from somatic cells early on in embryo development.…”

Mutation or not, what directly establishes a neoplastic state, namely cellular immortality and autonomy, still remains unknown and should be prioritized in our research

“…However, there probably are not any two of these 10 13 cells having exactly identical DNA sequences in the nuclear genome, which consists of 3.0-3.2 billion nucleotides in a diploid cell [4][5][6]. This is because development from a fertilized egg to an adult person involves numerous rounds of cell division, and during these divisions a huge number of genetic alterations have occurred, leastways many changes in single nucleotides [7][8][9][10][11]. These genetic alterations may occur via programs that had been evolutionarily entrenched in the genome, or may occur desultorily.…”