A Preliminary Study On Genetic Differentiation Among The Budgerigars During Their Domestication

Eight microsatellite primers developed for chickens have good abilities to cross-species amplification and polymorphisms among Budgerigars (Melopsittacus undulatus) at the first time. The results of genetic diversities indicated that a suite of microsatellite primers (MCW0085, lei0066, adl0166, mcw0145, mcw0032 and LEI0094) have strong universal application between chicken and budgerigars and can be used to assess various types of population-level analysis among domesticated commercial budgerigar populations. There was no relationship among success of amplification, phylogenetic distance and polymorphisms.Samples of studied domesticated budgerigars were divided into four plumage coloration patterns: green (POP1), yellow (POP2), sky-blue (POP3) and white (POP4). Using a set of 8-microsatellite primers, genetic variation was examined within and among budgerigars at the first time. Polymorphisms of overall 8-microsatellite loci were low to high. The allele numbers detected over loci was 3-8 and mean value was 4.8800; the expected heterozygosity ranged from 0.5350 to 0.7930 and mean value was 0.6616; the polymorphism information content (PIC) ranged from 0.4320 to 0.7590 and mean value was 0.6070. For overall loci per population, polymorphism information content (ranged from 0.5020(POP1) to 0.5760(POP2)), the observed heterozygosity(ranged from 0.4875(POP4) to 0.5667(POP2)) and the expected heterozygosity (ranged from 0.5607(POP1) to 0.6368 (POP4)).For polymorphism across all loci among populations, PIC was 0.5016(POP1) to 0.5761(POP4); the expected heterozygosity was 0.5607(POP1) to 0.6368(POP4) suggesting each locus has sufficient polymorphisms and can reflect the genetic structure within and relationship among populations, which exhibit powerful tools for examination of population genetics.Seven of 8 microsatellite primer sets except LEI0094 showed highly significant departure from Hardy-Weinberg equilibrium (p<0.01) among budgerigar populations. Significant deficiency of heterozygotes was shown within and among populations, which resulted in deviation from Hardy-Weinberg equilibrium in parts of loci. In addition, the design of primers cannot be performed directly through microsatellite flanking sequences of budgerigars and deficiency of heterozygotes needs to be studied further. Twenty-one of 32 population-locus combinations exhibited highly significant deviation from Hardy-Weinberg equilibrium (p<0.01). The results from Brookfield (1996) aquation estimates indicated that null allele frequency across loci which showed that heterozygote deficiency varied between 0.0495 (LEI0094) and 0.4595 (LEI0066), but MCW0032 exhibited little. The different degrees of disequilibrium were examined across each locus pair per population: maximum numbers of loci pairs was 3(POP1) and minimum was 2(POP4). For overall populations, genotypic combination of 14 loci pairs showed departure from Hardy-Weinberg equilibrium (p<0.01). Seven of 14 loci pairs was significant (p<0.05) and 4 highly significant (p<0.01) suggesting studied populations were not from mixed populations but genetically-isolated populations.Pairwise populations showed significant differentiation among four plumage coloration populations. Allele frequency differences between pairwise populations showed highly significant (p <0.01). Genotypic differentiation across all loci among four populations was highly significant (p<0.01); and further indicated that studiedpopulations were from non-mixture populations but genetically-isolated populations suggesting genetic differentiation mainly resulted from differences of genotypic frequencies of MCW0145 and MCW0032. FSt-value across each locus showed genetic differentiation among populations resulted from the genotypic difference of MCW0145, MCW0032. For all the populations, overall FsT-value across all loci was 0.122 (p<0.01) and indicated that differentiation of domesticated budgerigars is moderate (compared with spatial differentiation index Fst=0.0680~0.3740). Pairwise FsT-value among populations was 0.0744-0.1590 (p<0.01) and g...