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Patterns of Phylogeny in the Endemic Vascular Flora of the Juan Fernandez Islands, Chile

Tod F. Stuessy, Daniel J. Crawford and Clodomiro Marticorena
Systematic Botany
Vol. 15, No. 2 (Apr. - Jun., 1990), pp. 338-346
DOI: 10.2307/2419187
Stable URL: http://www.jstor.org/stable/2419187
Page Count: 9
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Patterns of Phylogeny in the Endemic Vascular Flora of the Juan Fernandez Islands, Chile
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Abstract

The Juan Fernandez Islands consist of two major islands: Masatierra (ca. 4 million years old) and Masafuera (1-2 million years old). These volcanic islands lie 600 km west of continental Chile at 33S latitude. Masafuera lies 150 km directly west of Masatierra. The endemic vascular flora of both islands numbers 123 species of which 99 are angiosperms and 24 are ferns. These species occur in 15 patterns of distribution on both islands. Three patterns of phylogeny are used to describe the origin of the endemic vascular flora: cladogenesis (a splitting event with extinction of the parental species), anagenesis (phyletic evolution), and anacladogenesis. The last pattern is a new term that describes a species arising from a progenitor that itself remains extant and undergoes little subsequent evolution. Analysis of patterns of phylogeny of all the endemic Juan Fernandez vascular flora reveals 71% anagenetic, 24% anacladogenetic, and 5% cladogenetic events. This strong evidence for phyletic change is consistent with small genetic alterations during speciation in rapidly changing environments with few vicariant events.

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