inheritance of brain size (interpretation of diallel crosses)

Guy F. Barbato gfb1 at psu.edu
Wed May 17 11:17:29 EST 1995

We are currently analyzing a series of experiments intended to elucidate the 
genetic architecture of brain size in chickens.  The data sets are comprised 
of 4 diallel crosses made up of related and unrelated 
populations of chickens (3, 4 and 5 parental stocks with brain and body 
weights measured at hatch through 84 days of age in both sexes).

During analysis of the data, using both the Griffing and Eberhart and Gardner 
models (similar to Gene Eisen's work in mice), we also performed the 
'traditional' Hayman's analysis (similar to Norm Henderson's work, also in 
mice).  We have found evidence for significant dominance for brain size using 
both types of analysis.

Curiously, we have observed that the expression of dominance differs between 
males and females.  females tend to exhibit sig. dominance variation at early 
ages which diminishes over time, while males exhibit increasing dominance at 
later ages.

Does anyone have any thoughts regarding possible genetic or evolutionary 
explanations of differential expression of dominance between the sexes??
please respond to me or to Gillian Leach (grl104 at email.psu.edu)

 ////         G. F. Barbato                Phone: (814)-865-4481
< * )         Dept. Poultry Science        FAX:   (814)-865-5691
  \ \__///    Penn State University        Lab:   (814)-865-3189
  ( --- )     University Park, PA 16802    Email: gfb1 at psu.edu
   \/ \/        **** URL: http://ps235.cas.psu.edu/ ****
     A non-secular nanosecond of thought:
            " Education is what survives when
                 what was learnt has been forgotten."
                                 --------  B.F. Skinner

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