Genetic Diversity and Population Structure of Three Strains of Indigenous Tswana Chickens and Commercial Broiler Using Single Nucleotide Polymormophic (SNP) Markers

The Tswana chicken is native to Botswana and comprises strains such as the naked neck, normal, dwarf, frizzled, and rumples. The origins of the different strains of Tswana chicken remain unknown and it is not yet clear if the different strains represent distinct breeds within the large Tswana chicken population. Genetic characterization of different strains of Tswana chickens using SNP arrays can elucidate their genetic relationships and ascertain if the strains represent distinct breeds of Tswana chicken population. The aim of this study was therefore to investigate population structure and diversity and to estimate genetic distances/identity between the naked neck, normal and dwarf strains of Tswana chickens. A total of 96 chickens (normal strain (n = 39), naked neck strain (n = 32), dwarf strain (n = 13) and commercial broiler (n = 12)) were used in the study. SNP genotyping was carried out using the Illumina chicken iSelect SNP 60 Bead chip using the Infinium assay compatible with the Illumina HiScan SQ genotyping platform. The observed heterozygosity (Ho) values were 0.610 ± 0.012, 0.611 ± 0.014, 0.613 ± 0.0006 for normal, naked neck and dwarf strains of Tswana chickens respectively and averaged 0.611 ± 0.016 across the three strains of Tswana chickens compared to Ho of 0.347 ± 0.023 in commercial broiler chicken. The expected heterozygosity (He) values were 0.613 ± 0.00012, 0.614 ± 0.00013, 0.608 ± 0.00021 for normal, naked neck and dwarf strains of Tswana chickens respectively and averaged 0.612 ± 0.00015 across the three strains of Tswana chickens compared to He of 0.577 ± 0.00022 in commercial broiler chicken. Principal component analysis (PCA) was used to get an insight into the population structure of indigenous Tswana chickens. The first two principal components revealed a set of three clusters. The normal strain of Tswana chicken and commercial broiler clustered together in one group. The dwarf strain clustered separately in one group and the naked neck and normal strains clustered together in the last group. The separate clustering of the dwarf strain from the rest of Tswana chicken strains suggests significant genetic uniqueness of the dwarf strain and very close genetic similarities between the normal and naked neck strains. The clustering pattern was confirmed by less genetic differentiation and less genetic distances between the naked neck and normal strains of Tswana chicken than between the two strains and the dwarf strain of Tswana chicken.

非洲习惯法学的开创者:评沙佩拉的法律人类学

艾萨克·沙佩拉出生于南非的犹太家庭,师从于英国人类学功能主义学派,先后任教于南非金山大学、开普敦大学以及英国伦敦政治经济学院。由于偶然的原因,他开启了对贝专纳保护国境内的茨瓦纳人的野调查,并持续了数年的时间。在法律人类学领域,他出版了两部专著以及近二十篇关涉茨瓦纳人习惯法的论文。在代表作《茨瓦纳人法律与习惯手册》中,他主张大而全的行文结构,区分法律与习惯,呈现习惯法的复杂性,并超越了功能主义视角。沙佩拉全面开创了法律人类学的非洲研究,其作品对于今天的博茨瓦纳依然有着重要影响,他是法律人类学领域一位承前启后的重要学者。