Evolution of genome size in the Dasycladales (Chlorophyta) as determined by DAPI cytophotometry
1998
Kapraun, Donald F. | Buratti, Jason R.
Microspectrophotometry with the DNA-localizing fluorochrome 4′,6-diamidino-2-phenylindole (DAPI) was used to estimate nuclear genome sizes in 12 species representing two families of the Dasycladales. Estimated 2C DNA contents in these taxa range from 0.7–1.4 pg in the family Dasycladaceae and from 0.9–2.4 pg in the family Acetabulariaceae. In both families, species exhibiting characteristics considered to be primitive appear to have 2C DNA contents that approximate 50% of values found in species exhibiting characteristics considered to be more advanced. Results suggest that polyploidy events have accompanied evolution in the order but apparently have been infrequent and conservatively preserved, leading to a narrow range of relatively small genome sizes. Limitations on genome size increase are discussed in terms of constraints imposed by a prolonged uninucleate stage. Interspecific comparisons of genome size and gametangium volume suggest an inverse relationship. Gametangium volume appears to have phylogentic significance, in that taxa with more advanced characteristics generally have smaller gametangia.
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