A less selfish view of genome size evolution in maize

• Published in: PLoS genetics Vol. 14; no. 5; p. e1007249
• Main Authors: Kreiner, Julia M., Wright, Stephen I.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 10.05.2018; Public Library of Science (PLoS)
• Subjects: Adaptation; Biology and Life Sciences; Botanical research; Cell cycle; Chromosomes; Corn; Deoxyribonucleic acid; DNA; Evolution; Evolution, Molecular; Evolutionary adaptation; Evolutionary biology; Genetic aspects; Genetic research; Genome Size; Genome, Plant; Genomes; Metabolism; Natural history; Physiology; Poaceae; Population; Quantitative genetics; Research and Analysis Methods; Zea mays; Zea mays - genetics; Toronto Ontario Canada; Canada
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1007249

Genome size varies by many orders of magnitude across plants and animals, but resolving the most important evolutionary forces driving this variation remains challenging. Since eukaryotic genome size variation is not associated with complexity, genetic drift of the amount of noncoding DNA could dominate, implicating population and species history as key drivers of shifts in DNA content. Alternatively, directional selection could be acting on DNA content, but if so, it has not been resolved which level of selection is most important. Since the predominant component of many eukaryotic genomes is comprised of selfish genetic elements such as transposable elements (TEs) and regions subject to meiotic drive, factors that influence their differential success across populations and species could account for much of the variation in genome size. [6] add to this rich literature by using a quantitative genetics framework to conduct a test of local adaptation, recognizing that genome size is a trait governed by an immense number of small-effect loci. [...]it can be thought of as a quantitative trait under complete genetic control, since the variation in genome size is expected to be a simple function of the net number of insertion and deletion alleles individuals have across the genome. Conversely, other selective pressures on selfish genetic elements may provide an additional source of genome size variation in maize populations beyond the effects of flowering time. Since chromosomal knobs are known to have severe fitness costs, the extent of these costs may well depend on the environment [22], possibly explaining the disproportionate effect of altitude on knobs when genome size is controlled for in this study.