Biology is now entering the new era of systems biology and exerting a growing influence on the future development of various disciplines within life sciences. In early classical and molecular periods of Biology, the theoretical frames of classical and molecular quantitative genetics have been systematically established, respectively. With the new advent of systems biology, there is occurring a paradigm shift in the field of quantitative genetics. Where and how the quantitative genetics would develop after having undergone its classical and molecular periods? This is a difficult question to answer exactly. In this perspective article, the major effort was made to discuss the possible development of quantitative genetics in the systems biology era, and for which there is a high potentiality to develop towards "systems quantitative genetics". In our opinion, the systems quantitative genetics can be defined as a new discipline to address the generalized genetic laws of bioalleles controlling the heritable phenotypes of complex traits following a new dynamic network model. Other issues from quantitative genetic perspective relating to the genetical genomics, the updates of network model, and the future research prospects were also discussed.

The genetic diversities and relationships of 10 Chinese indigenous pig breeds and three exotic pig breeds have been evaluated using 26 microsatellites recommended by the Food and Agriculture Organization & the International Society of Animal Genetics (FAO-ISAG). The allele frequencies, genetic heterozygosity (H) and polymorphism information content (PIC) have been calculated. The results showed that genetic diversity of Chinese indigenous pig breeds is higher than that of the introduced pig breeds. The clustering of 10 breeds is generally consistent with their geographical distribution.

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Genetic diversity of four quail populations, including Korean quails (maroon quails), Peking white quails, Chinese yellow quails and Chinese black quails, were analyzed by microsatellite markers, aiming to provide scientific basis for new breeds of Chinese black quails for egg production as well as the assessment, protection and utilization of Chinese quail’s genetic resources. The results showed that 48 alleles were detected by nine microsatellite markers in the four quail populations, with the mean of 5.33 alleles in each locus. The average effective number of alleles marked by the nine microsatellite markers in Chinese black quails, Peking white quails, Chinese yellow quails and maroon quails were 3.5338, 3.6135, 4.0312 and 3.6508 respectively. The average heterozygosity of the four quail populations were 0.6952, 0.7046, 0.7353 and 0.7096 respectively. The average polymorphic information content of nine microsatellite loci in four quail populations were 0.6204, 0.6587, 0.6942 and 0.6639, respectively, all of which were greater than 0.5, indicating the four populations’ copious genetic diversity. In this study, the average genetic differentiation coefficient among populations was 0.0349, so the genetic variation among populations accounted for 3.49%, which demonstrated that genetic variation among populations was just a small proportion of the total population genetic variation, and there was little differentiation among the four populations. Cluster analysis indicated that Chinese black quails and Peking white quails were firstly clustered, and then Chinese yellow quails and maroon quails were clustered, and finally the two were clustered together.

Seventeen Chinese indigenous pig breeds and three introduced pig breeds had been carried out by means of vertical polyacrylamide gel electrophoresis (PAGE). According to the results, eight serum protein loci were highly polymorphic except Pi-2 and Cp. The polymorphism information content (PIC) of Hpx was the highest (0.5268), while that of Cp was the lowest (0.0257). The population genetic variation index showed that about 84% genetic variation existed in the population, and the rest of 16% distributed between the populations. The genetic variation of Yimeng black pig and Duroc were the highest and the lowest, respectively. The genetic variation of Chinese indigenous pig breeds was much more than that of exotic groups. Genetic distance results showed that Chinese indigenous pig breeds were classified into four groups with the three introduced pig breeds clustered into another group. The results also supported the geographic distribution of Chinese indigenous pig breeds in certain extent.