Extreme chromosomal differentiation in the Goodeid fish genus Ilyodon

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.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Zoology

Department dc:contributor.department

Zoology

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1982

Author dc:creator

• Worrell, Robert Andrew

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/80196

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/80196