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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Extreme chromosomal differentiation in the Goodeid fish genus Ilyodon

Worrell, Robert Andrew January 1982 (has links)
The llyodon of the Rio Coahuayana river system (Colima and Jalisco, Mexico) have undergone extensive chromosomal differentiation without associated morphological differentiation. Two cytotypes differing by at least 6 fixed pericentric inversions were found. Hybrids between the two cytotypes produced in the laboratory were found to be fertile, indicating there is little or no heterozygote disadvantage associated with these inversions. Models depending primarily on drift and inbreeding to fix rearrangements were rejected because the apparent population structure makes them unlikely and the lack of a heterozygote disadvantage makes them unnecessary. Instead, it is concluded that selection differences operated to fix these inversions. / Master of Science

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