THE ORIGIN OF SUPERNUMERARY CHROMOSOMES IN NATURAL POPULATIONS OF<i>CLARKIA ELEGANS</i>

Lewis, Harlan

doi:10.1111/j.1558-5646.1951.tb02770.x

Cited by 77 publications

(59 citation statements)

References 12 publications

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“…An example of an ineffective variant is that of a tetraploid anther in an otherwise diploid flower of C. unquiculata (Lewis, 1951). Similar abnormalities doubtless recur in this and other species, but no EVOLUTION IN CLARKIA 5 naturally occurring autoploids are known in the genus.…”

Section: Diploid Speciesmentioning

confidence: 99%

“…Chromosomal differences within populations are known in several species of Clarkia, particularly C. amoena (Hakansson, 1942;Hiorth, 1942a) and C. unguiculata (Lewis, 1951). These differences involve both chromosomal rearrangements and chromosome numbers, but not polyploidy.…”

Section: Diploid Speciesmentioning

confidence: 99%

“…The 8 HARLAN LEWIS latter have not as yet been identified in any natural population of Clarkia. However, inversions involving the centromere have been postulated (Lewis, 1951) as a reason for the failure of chiasma formation that has been observed in certain chromosomes of several species. The reason for the apparent absence or infrequent occurrence of inversion heterozygotes is not clear and may merely refleet too few observations.…”

Section: Diploid Speciesmentioning

confidence: 99%

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THE MECHANISM OF EVOLUTION IN THE GENUSCLARKIA

Lewis

1953

Evolution

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Section: Diploid Speciesmentioning

confidence: 99%

Section: Diploid Speciesmentioning

confidence: 99%

Section: Diploid Speciesmentioning

confidence: 99%

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THE MECHANISM OF EVOLUTION IN THE GENUSCLARKIA

Lewis

1953

Evolution

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“…Tertiary trisomics, with the extra chromosome composed of segments of two nonhomologous chromosomes of the basic set, seem better suited for B chromosome formation. They regularly appear in the progenies of heterozygotes for translocations (eg, Ramage, 1960), which are known to be widespread in plant populations (Lewis, 1951;James, 1965;Wedberg et al, 1968). Moreover, it is well known that in wild populations, plants heterozygous for a translocation may contain sporophytic lethals near the breakpoints (Cleland, 1962;James, 1965).…”

Section: Introductionmentioning

confidence: 99%

Tertiary trisomics in the garden pea as a model of B chromosome evolution in plants

et al. 2003

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It is hypothesized that, in plants, genetically empty B chromosomes may originate from the extra chromosome (E) of tertiary trisomics if (i) the region of basic chromosomes homologous to the E (H-region) harbors a sporophytic lethal covered by the wild-type allele in E, and (ii) crossing-over between E and the H-region is suppressed. Under these conditions, most loss-of-function mutations occurring in the H-region are deleterious for haploid gametophytes, whereas those occurring in E are neutral or advantageous for hyperploid (n þ 1) gametophytes. As a result, natural selection at the gametophyte level can lead to the degeneration of E, leaving the H-region intact. Using Hammarlund translocation T(3-6)a, we synthesized two trisomic lines of the garden pea (Pisum sativum L.), where E was composed of the short arms of chromosomes 3 and 6 and the H-region carried recessive markers. In the trisomic line TRIS, we found few crossovers between E and the H-region. In the trisomic line TRUST, obtained after a change of basic chromosome constitution, recombination in this region was completely suppressed. After induction in the H-region of TRUST of a recessive sporophytic mutation rmv, two 15-chromosome lines of stable trisomics were established. One of them passed 11 generations, having produced more than 6000 individuals, all of them trisomic, and E remained present as a single element with no pairing partners. No tetrasomics were dete-cted in these lines. If such trisomics occurred in nature, their extra chromosomes are likely to become a B chromosome.

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“…Centaurea scabiosa (Frost, 1958), Clarkia elegans (Lewis, 1951), Festuca pratensis (Bosemark,I 956a), Lilium aulatum (Ogihara, 1962), Lilium callosum (Kayano, 1962), Lilium medeoloides (Samejima, 1958), Myrmeleotettix maculatus (John and Hewitt, 1965;Barker, 1966), P/ileum phleoides (Bosemark, 1956b(Bosemark, , 1967, Pseudococcus obscurus (Nur, 1962), and Secale cereale (Muntzing, 1950(Muntzing, , 1957Lee and Mm, 1965). Correlations between certain environmental factors and the frequency of B's have been found in Centaurea scab iosa (Frost, 1958), in Festuca pratensis (Bosemark, 1956a), in Phleum phleoides (Bosemark, 1956b(Bosemark, , 1967, in Secale cereale (Lee, 1966), and in Myrmeleotettix maculatus (Barker, 1966;Hewitt and John, 1967).…”

Section: Introductionmentioning

confidence: 99%