Reports

Evolutionary Significance of Polyploidy in the Pteridophyta

Science  15 Jul 1966:
Vol. 153, Issue 3733, pp. 305-307
DOI: 10.1126/science.153.3733.305

Abstract

Polyploidy occurs in the heterosporous and homosporous Pteridophyta, but with a much higher frequency in the latter. Ninety-six percent of the homosporous Pteridophyta show a gametic chromosome number greater than 27, whereas 90 percent of the heterosporous ones possess a gametic chromosome number less than 28. Ultrafrequent establishment of poly- ploidy in the homosporous Pteridophy- ta appears to be necessary to create and maintain genetic variation in the face of the homozygotizing effects of habitual self-fertilization in the monoe- cious gametophytes of these plants.

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