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Comparison of Fern and Flowering Plant Distributions with Some Evolutionary Interpretations for Ferns
Alan R. Smith
Vol. 4, No. 1 (Apr., 1972), pp. 4-9
Published by: Association for Tropical Biology and Conservation
Stable URL: http://www.jstor.org/stable/2989639
Page Count: 6
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The percentage of pantropical and amphioceanic genera of ferns far exceeds similar percentages for angiosperms. Conversely, the number of "endemic" fern genera is much lower than the comparable figure for flowering plants. Comparison of the two groups of plants on islands points out even more strikingly the lower percentages of generic and specific endemism of ferns. These distributional differences cannot be accounted for by the longer geologic history of ferns, but can be attributed to their greater dispersibility. The wider distribution of ferns, together with the absence of many of the speciation barriers operative in angiosperms, has contributed to a relatively slower rate of speciation in the ferns, and probably also to a lower extinction rate. Delimitation of generic and suprageneric taxa is therefore more difficult in many cases.
Biotropica © 1972 Association for Tropical Biology and Conservation