The Role of Structural Variation in Adaptation and Evolution of Yeast and Other Fungi

Abstract

Mutations in DNA can be limited to one or a few nucleotides, or encompass larger deletions, insertions, duplications, inversions and translocations that span long stretches of DNA or even full chromosomes. These so-called structural variations (SVs) can alter the gene copy number, modify open reading frames, change regulatory sequences or chromatin structure and thus result in major phenotypic changes. As some of the best-known examples of SV are linked to severe genetic disorders, this type of mutation has traditionally been regarded as negative and of little importance for adaptive evolution. However, the advent of genomic technologies uncovered the ubiquity of SVs even in healthy organisms. Moreover, experimental evolution studies suggest that SV is an important driver of evolution and adaptation to new environments. Here, we provide an overview of the causes and consequences of SV and their role in adaptation, with specific emphasis on fungi since these have proven to be excellent models to study SV.

Keywords: adaptation; fungi; structural variation.

Figure 1

Types of structural variation.

Figure 2

Mechanisms of SV formation. (A) Events leading to aneuploidy. (B) Events leading to replication fork collapse. (C) SV formation as a result of stalled replication fork reactivation. (D) SV formation mediated by homologous recombination. (E) SV formation mediated by nonhomologous end joining. (F) Origin-dependent inverted-repeat amplification.

Figure 2

Mechanisms of SV formation. (A) Events leading to aneuploidy. (B) Events leading to replication fork collapse. (C) SV formation as a result of stalled replication fork reactivation. (D) SV formation mediated by homologous recombination. (E) SV formation mediated by nonhomologous end joining. (F) Origin-dependent inverted-repeat amplification.