RT Journal
A1 Chase, Kevin
A1 Carrier, David R.
A1 Adler, Frederick R.
A1 Ostrander, Elaine A.
A1 Lark, Karl G.
T1 Interaction between the X chromosome and an autosome regulates size sexual dimorphism in Portuguese Water Dogs
JF Genome Research 
JO Genome Research 
YR 2005 
FD December 01 
VO 15 
IS 12 
SP 1820 
OP 1824 
DO 10.1101/gr.3712705 
UL http://genome.cshlp.org/content/15/12/1820.abstract 
AB Size sexual dimorphism occurs in almost all mammals. In Portuguese Water Dogs, much of the difference in skeletal size between females and males is due to the interaction between a Quantitative Trait Locus (QTL) on the X-chromosome and a QTL linked to Insulin-like Growth Factor 1 (IGF-1) on the CFA 15 autosome. In females, the haplotype of CFA 15 resulting in small size is dominant. In males, the haplotype for large size is dominant. Females, homozygous at the CHM marker on the X chromosome and homozygous for the large size CFA 15 haplotype are, on average, as large as large males. However, all females that are heterozygous at the CHM marker are small, regardless of their CFA 15 genotype. This interaction suggests a genetic mechanism that in turn leads to a scenario for the evolution of size sexual dimorphism consistent with a proposal of Lande that sexual dimorphism can evolve because females secondarily become smaller than males as a consequence of natural selection for optimal size. Our results also can explain Rensch's Rule, which states that size is often positively correlated with the level of size sexual dimorphism.