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CHROMOSOME NUMBERS FROM THE FLORA OF THE JUAN FERNANDEZ ISLANDS
Author(s) -
Sanders Roger W.,
Stuessy Tod F.,
Rodriguez Roberto
Publication year - 1983
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1983.tb06415.x
Subject(s) - biology , botany , endemism , polyploid , flora (microbiology) , myrtaceae , ploidy , ecology , gene , genetics , bacteria , biochemistry
Forty‐one chromosome counts are reported for 29 species of the flora of the Juan Fernandez Islands, Chile. Counts are provided for the first time for Azara (Flacourtiaceae), Cuminia (Lamiaceae), Dysopsis (Euphorbiaceae), Raphithamnus (Verbenaceae), Robinsonia (Asteraceae) and Ugni (Myrtaceae). New species counts are in Dendroseris and Erigeron (Asteraceae), Eryngium (Apiaceae), Escallonia (Saxifragaceae), Haloragis (Haloragaceae), Libertia (Iridaceae), Myrceugenia (Myrtaceae), Pernettya (Ericaceae), Peperomia (Piperaceae), Spergularia (Caryophyllaceae), and Wahlenbergia (Campanulaceae). The level of recent polyploidy and aneuploidy in the chromosomally known flora is each estimated conservatively at 6%. Almost all of the endemic lineages appear to have evolved at the same ploidy level from their polyploid mainland relatives. Furthermore, there is no evidence for chromosomal evolution by euploidy or aneuploidy within endemic genera. The level of ancient polyploidy in the endemic Juan Fernandez flora is estimated to be 66%. This high level correlates with the idea that many of the woody endemics (comprising nearly one‐half of the woody species in our chromosomal sample) have been derived paedomorphically from herbaceous perennial mainland ancestors in temperate, orogenetically active, Andean regions, in which high levels of polyploidy would be expected.