In Cryptococcus neoformans var. grubii (Cng) copy number variation (CNV) is happening on at least two levels. On one hand Chow et al. show not only that there natural polymorphism in copy number in a tandem repeat of a gene (ARR3), but that copy number can be selected for via arsenite. ARR3, the arsenite efflux transporter gene they found was located in the subtelomeric region of Chromosome 3, and subtelomeric regions are thought to undergo structural variation at a higher rate than other parts of the genome. However, Cng also shows evidence rapid adaptive aneuploidy or chromosomal copy number variation (CCNV). I have yet to see an estimate of these rates of CNV or CCNV in Cng populations. Does the presence of CCNV promote CNV or vice versa in Cng? Chow et al. show that the arsenite CNV example does not effect virulence, but most of the CCNV work suggests some strong effects on azole resistance which in turn effects patient outcome. These are clearly evolutionary mechanisms that fungal evolutionary biologists should try to understand better.
Eve W. L. Chow, Carl A. Morrow, Julianne T. Djordjevic, Ian A. Wood, & James A. Fraser (2012). Microevolution of Cryptococcus neoformans Driven by Massive Tandem Gene Amplification Molecular Biology and Evolution DOI: 10.1093/molbev/mss066