Chromosome "fusions" in karyotype evolution

Lysak MA

McGraw-Hill Yearbook of Science & Technology 2015: 50-53.


The karyotype is the complement of chromosomes characteristic of an individual, species, genus, or other grouping. Eukaryotic organisms vary in their number of chromosomes, from 1 to 600 per haploid genome (the genes that make up a haploid set of chromosomes). Haploid cells contain a single set of chromosomes. This is in contrast to diploid cells, which contain two complete sets of chromosomes. Although the number of chromosomes is usually species-specific, it can increase or decrease in populations or species. The number of chromosomes can increase through polyploidy (whole-genome duplication), that is, duplication of a whole chromosome set (or sets), or by centric fission, that is, centromere breakage, splitting the original chromosome into two chromosomes. The loss or gain of a single chromosome or a few chromosomes, called aneuploidy, can be caused by erroneous separation of chromatids or chromosomes during meiosis or mitosis. ...