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. 1989 Sep;86(17):6666–6670. doi: 10.1073/pnas.86.17.6666

Exceptional chromosomal mutations in a rodent population are not strongly underdominant.

M W Nachman 1, P Myers 1
PMCID: PMC297906  PMID: 2771951

Abstract

The observation of karyotypic uniformity in most species has led to the widespread belief that selection limits chromosomal change. We report an unprecedented amount of chromosomal variation in a natural population of the South American marsh rat Holochilus brasiliensis. This variation consists of four distinct classes of chromosomal rearrangements: whole-arm translocations, pericentric inversions, variation in the amount of euchromatin, and variation in number and kind of supernumerary (B) chromosomes. Twenty-six karyotypes are present among 42 animals. Observations of the natural population over a 7-year period and breeding experiments with captive animals indicate that heterozygous individuals suffer no detectable reduction in fitness. This is at odds with a central assumption in current models of chromosomal speciation and provides a firm rejection of the view that selection necessarily restricts chromosomal change.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Capanna E. Robertsonian numerical variation in animal speciation: Mus musculus, an emblematic model. Prog Clin Biol Res. 1982;96:155–177. [PubMed] [Google Scholar]
  2. Davisson M. T., Akeson E. C. An improved method for preparing G-banded chromosomes from mouse peripheral blood. Cytogenet Cell Genet. 1987;45(2):70–74. doi: 10.1159/000132432. [DOI] [PubMed] [Google Scholar]
  3. EVANS E. P., BRECKON G., FORD C. E. AN AIR-DRYING METHOD FOR MEIOTIC PREPARATIONS FROM MAMMALIAN TESTES. Cytogenetics. 1964;3:289–294. doi: 10.1159/000129818. [DOI] [PubMed] [Google Scholar]
  4. King M. Chromosomal rearrangements, speciation and the theoretical approach. Heredity (Edinb) 1987 Aug;59(Pt 1):1–6. doi: 10.1038/hdy.1987.90. [DOI] [PubMed] [Google Scholar]
  5. Koop B. F., Baker R. J., Genoways H. H. Numerous chromosomal polymorphisms in a natural population of rice rats (Oryzomys, Cricetidae). Cytogenet Cell Genet. 1983;35(2):131–135. doi: 10.1159/000131854. [DOI] [PubMed] [Google Scholar]
  6. Patton J. L. Chromosome studies of certain pocket mice, genus Perognathus (Rodentia: heteromyidae). J Mammal. 1967 Feb;48(1):27–37. [PubMed] [Google Scholar]
  7. Searle J. B. Meiotic studies of Robertsonian heterozygotes from natural populations of the common shrew, Sorex araneus L. Cytogenet Cell Genet. 1986;41(3):154–162. doi: 10.1159/000132220. [DOI] [PubMed] [Google Scholar]
  8. Stewart-Scott I. A., Bruère A. N. Distribution of heterozygous translocations and aneuploid spermatocyte frequency in domestic sheep. J Hered. 1987 Jan-Feb;78(1):37–40. doi: 10.1093/oxfordjournals.jhered.a110304. [DOI] [PubMed] [Google Scholar]
  9. White M. J. Models of speciation. New concepts suggest that the classical sympatric and allopatric models are not the only alternatives. Science. 1968 Mar 8;159(3819):1065–1070. doi: 10.1126/science.159.3819.1065. [DOI] [PubMed] [Google Scholar]
  10. White M. J. Rectangularity, speciation, and chromosome architecture. Prog Clin Biol Res. 1982;96:75–103. [PubMed] [Google Scholar]

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