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CHROMOSOME NUMBERS, PHYLOGENY, PHYTOGEOGRAPHY OF THE ANNONACEAE AND THEIR BEARING ON THE (ORIGINAL) BASIC CHROMOSOME NUMBER OF ANGIOSPERMS
Author(s) -
Walker James W.
Publication year - 1972
Publication title -
taxon
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 81
eISSN - 1996-8175
pISSN - 0040-0262
DOI - 10.2307/1219222
Subject(s) - annonaceae , biology , chromosome , chromosome number , pollen , karyotype , botany , genus , evolutionary biology , genetics , gene
Summary Chromosome numbers are summarized within a novel taxonomic framework for the 22 genera of the primitive angiosperm family Annonaceae in which they are known. Chromosomal data are shown to be consistent with the author's concept of the phylogeny of the family, as independently determined from a study of pollen and floral morphology. This independently derived infrafamilial phylogeny suggests that there have been minimally 12 separate changes in base chromosome number within the family. Evidence is strong for considering x = 7 as the base chromosome number for the family, with parallel ascending aneuploidy: n = 7→8→9. Considerable parallel polyploidy has occurred on the older x = 7, polyploidy has occurred at least once on x = 8, while the most recent aneuploid number, x = 9, has not produced any polyploids as far as is known. Chromosome numbers, as well as pollen and floral morphology, are adduced to support the author's conclusion that the Annonaceae are of New World (and/or possibly African) origin. The significance of chromosome evolution within the Annonaceae is discussed as it bears on the choice of the basic chromosome number for the angiosperms (x = 7). Finally, the first chromosome count, n = 8, is presented for the annonaceous genus Desmopsis Saff.