Chromosome Research

, Volume 7, Issue 4, pp 289-295

First online:

Comparative Painting Reveals Strong Chromosome Homology Over 80 Million Years of Bird Evolution

  • Swathi ShettyAffiliated withDepartment of Biochemistry and Genetics, La Trobe University
  • , Darren K. GriffinAffiliated withDepartment of Biological Sciences, Brunel University
  • , Jennifer A. Marshall GravesAffiliated withDepartment of Biochemistry and Genetics, La Trobe University Email author 

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Chickens and the great flightless emu belong to two distantly related orders of birds in the carinate and ratite subclasses that diverged at least 80 million years ago. In the first ZOO-FISH study between bird species, we hybridized single chromosome paints from the chicken (Gallus domesticus) onto the emu chromosomes. We found that the nine macrochromosomes show remarkable homology between the two species, indicating strong conservation of karyotype through evolution. One chicken macrochromosome (4) was represented by a macro- and a microchromosome in the emu, suggesting that microchromosomes and macrochromosomes are interconvertible. The chicken Z chromosome paint hybridized to the emu Z and most of the W, confirming that ratite sex chromosomes are largely homologous; the centromeric region of the W which hybridized weakly may represent the location of the sex determining gene(s).

chicken emu microchromosomes sex chromosomes ZOO-FISH