Linkage disequilibrium between the pseudoautosomal PEPB-1 locus and the sex-determining region of chinook salmon.
Allele frequency differences between sexes and an excess of heterozygotes in males had suggested that the PEPB-1 locus is sex-linked in chinook salmon (Oncorhynchus tshawytscha). We here estimate less than 1% recombination between PEPB-1 and a growth hormone pseudogene known to be in the sex-determining region (SEX) in 374 progeny from eight experimental matings. We present modified maximum likelihood methods for estimating haplotype frequencies from population samples at a sex-linked locus in which functional alleles occur on both the X and Y chromosomes (pseudoautosomal loci). We find nearly complete linkage disequilibrium between PEPB-1 and SEX in 20 population samples from the Puget Sound region of Washington and southern British Columbia. However, allele frequencies at PEPB-1 were similar in males and females in 35 population samples from the coast of Washington and the Columbia River basin. Pseudoautosomal regions have been described in a broad taxonomic array of vertebrates and invertebrates, and they are likely candidate regions to find genes associated with differences in life history, morphology, or behavior between males and females.
Marshall
A R
AR
Washington Department of Fish & Wildlife, 600 Capitol Way N., Olympia, WA 98501, USA.
Knudsen
K L
KL
Allendorf
F W
FW
D000818:Animals; D005260:Female; D005787:Gene Frequency; D005828:Genetics, Population; D005843:Geography; D006239:Haplotypes; D016013:Likelihood Functions; D015810:Linkage Disequilibrium; D008297:Male; D011544:Pseudogenes; D011995:Recombination, Genetic; D012474:Salmon / Q000235:genetics*; D013045:Species Specificity; D014960:X Chromosome; D014998:Y Chromosome