Distribution of Structural Hybrids in Paeonia Californica

Walters, James L.

doi:10.1002/j.1537-2197.1942.tb14005.x

Cited by 35 publications

(21 citation statements)

References 13 publications

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“…For this reason interchanges become established within populations only when their contribution to fitness more than compensates for the infertility. Cases have been described in Gampanula persicfiora (Darlington and La Cour, 1950), Paeonia ca4fornica (Walters, 1942) and Periplaneta americana (Lewis and John, 1957), where the interchanges "float" within populations made up of interchange heterozygotes and of individuals homozygous for the interchanges and for the normal standard chromosomes. These species are, normally, outbreeding but in all the populations with interchanges in high frequency there was a degree of inbreeding imposed by isolation.…”

mentioning

confidence: 99%

Interchange heterozygotes versus homozygotes

1976

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mentioning

confidence: 99%

Interchange heterozygotes versus homozygotes

1976

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“…The individuals of the species studied by the writers may be unstablized "floating" variants in a widely cultivated and distributed species. Like Paeonia californica (Walters 1942) it may be profitable to map these species throughout the range of its distribution (both under wild and cultivated conditions), in relation to varia bility in morphology, breeding system and chromosomal polymorphism, and look for correlations, if any.…”

Section: Observationsmentioning

confidence: 99%

“…Sax and Anderson (1932) observed interlocked bivalents in all diploid Tradescantias. Walters (1942) is of the opinion that in Paeonia the size of ring has increased through in terlocking. In the present case 6.2% cells contained interlocking involving 2 to 4 bivalents and/or a bivalent and interchange multiple of 6 (Table 3, .…”

Section: Observationsmentioning

confidence: 99%

Cytogenetics of Tropical Bulbous Ornamentals

Khoshoo

Raina

1968

CYTOLOGIA

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“…HETEROZYGOSITY for reciprocal translocations has been reported in several groups of flowering plants, such as Gaura (Bhaduri, 1942;Raven and Gregory, 1972), Gayophytum (Lewis and Sweykowski, 1964), Hypericum (Hoar, 1931), Rhoeo spathecea (Sax, 1931(Sax, , 1935, Paeonia (Stebbins and Ellerton, 1939;Walters, 1942), Chrysanthemum (Rana and Jam, 1965), Clarlcia (Mooring, 1958;Wedberg, Lewis and Venkatesh, 1968), and Isotoma (James, 1965(James, , 1970. The classical example is, of course, that of Oenothera, reviewed by Cleland (1972).…”

Section: Introductionmentioning

confidence: 99%

A model for the evolution of translocation heterozygosity

Malefijt

Charlesworth

1979

Heredity

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SUMMARYThis paper uses algebraic analysis and computer simulation to examine the contribution of homozygote disadvantage created by mutational load to selection for translocation heterozygosity in selfing populations. It is shown first that in structurally homozygous populations mutation pressure can lead to the accumulation of deleterious mutations, as opposed to the establishment of a stable equilibrium between mutational input and selective elimination. The speed of accumulation depends on the mutation rate and inversely on the selection coefficients against deleterious alleles, the population size and the amount of recombination. It is also shown that translocations can be selected, given a sufficiently high rate of mutation per chromosome and provided that crossing-over is suppressed in structural heterozygotes. Incomplete dominance of deleterious mutations lowers the strength of selection for translocations, compared with the case of complete recessivity. In all cases when translocations are selected there is accumulation of deleterious genes in structural heterozygotes, so that the final population consists entirely of structural heterozygotes, the homozygotes behaving effectively as recessive lethals.The model is discussed in relation to what is known about translocation heterozygosity in natural populations, and about mutation rates and selection coefficients for deleterious genes. It is concluded that an unrealistically high mutation rate is probably needed for this mechanism to be the sole factor involved in initiating the evolution of complex heterozygosity in largely selffertilising plants. It may, however, be an important contributary factor, and we show that it is likely to be more important, the larger the number of interchanges already established in the population.

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Distribution of Structural Hybrids in Paeonia Californica

Cited by 35 publications

References 13 publications

Interchange heterozygotes versus homozygotes

Interchange heterozygotes versus homozygotes

Cytogenetics of Tropical Bulbous Ornamentals

A model for the evolution of translocation heterozygosity

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