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Stability of Chromosomal Hybrid Zone in the Clarkia nitens and Clarkia speciosa Ssp. Polyantha Complex (Onagraceae)
Donald P. Hauber and William L. Bloom
American Journal of Botany
Vol. 70, No. 10 (Nov. - Dec., 1983), pp. 1454-1459
Published by: Botanical Society of America, Inc.
Stable URL: http://www.jstor.org/stable/2443343
Page Count: 6
You can always find the topics here!Topics: Chromosomes, Hybridity, Taxa, Geographic regions, Population mean, Evolution, Chromosome translocation, Plants, Genetic hybridization, Population growth
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Clarkia nitens and Clarkia speciosa polyantha (Onagraceae) are distinct chromosomal taxa differing by at least six reciprocal translocations. Where the taxa have come into contact, a chromosome boundary zone exists characterized by high levels of translocation heterozygosity due to at least 12 new chromosome arrangements which have evolved there. Previous studies have shown that these boundary arrangements are distributed such that they provide for full interfertility between adjacent populations. It was hypothesized that the geographic distributions of each of these arrangements will remain generally stable due largely to the very adverse effect that major changes would have on fertility. Evidence is presented here that over a ten year period the frequencies and geographic distributions of the chromosome arrangements within this boundary region have remained stable. The frequencies of the various chromosomal configurations (nine pairs, ring of four, two rings of four, ring of six, ring of four + ring of six, and ring of eight) from surveys in 1968 and 1978 have been analyzed statistically. In general, the analysis indicates that there have been no detectable changes over the 10-yr period.
American Journal of Botany © 1983 Botanical Society of America, Inc.