RESUMO
To determine the genetic diversity and paternal origin of Chinese cattle, 302 males from 16 Chinese native cattle breeds as well as 30 Holstein males and four Burma males as controls were analysed using four Y-SNPs and two Y-STRs. In Chinese bulls, the taurine Y1 and Y2 haplogroups and indicine Y3 haplogroup were detected in seven, 172 and 123 individuals respectively, and these frequencies varied among the Chinese cattle breeds examined. Y2 dominates in northern China (91.4%), and Y3 dominates in southern China (90.8%). Central China is an admixture zone, although Y2 predominates overall (72.0%). The geographical distributions of the Y2 and Y3 haplogroup frequencies revealed a pattern of male indicine introgression from south to north China. The three Y haplogroups were further classified into one Y1 haplotype, five Y2 haplotypes and one Y3 haplotype in Chinese native bulls. Due to the interplay between taurine and indicine types, Chinese cattle represent an extensive reservoir of genetic diversity. The Y haplotype distribution of Chinese cattle exhibited a clear geographical structure, which is consistent with mtDNA, historical and geographical information.
Assuntos
Bovinos/genética , Variação Genética , Repetições de Microssatélites/genética , Cromossomo Y/genética , Animais , Cruzamento , China , DNA Mitocondrial/química , DNA Mitocondrial/genética , Pai , Frequência do Gene , Geografia , Haplótipos , Masculino , Filogenia , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA/veterináriaRESUMO
Despite the Icelandic horse enjoying great popularity worldwide, the breed's gene pool is small. This is because of a millennium of isolation on Iceland, population crashes caused by natural disasters and selective breeding. Populations with small effective population sizes are considered to be more at risk of selection pressures such as disease and environmental change. By analysing historic and modern mitochondrial DNA sequences and nuclear coat colour genes, we examined real-time population dynamics in the Icelandic horse over the last 150 years. Despite the small gene pool of this breed, we found that the effective population size and genetic profile of the Icelandic horse have remained stable over the studied time period.
Assuntos
Cruzamento , Pool Gênico , Instabilidade Genômica , Cavalos/genética , Alelos , Animais , DNA Mitocondrial/genética , Meio Ambiente , Cavalos/classificação , Islândia , Densidade Demográfica , Dinâmica PopulacionalRESUMO
Previous mitochondrial DNA (mtDNA) D-loop and microsatellite studies have shown that Chinese horses have multiple maternal origins and high genetic diversity. To better characterize maternal genetic origins and diversity of Chinese domestic horses, we conducted a comprehensive analysis of 407 complete 1140 bp sequences of the horse mitochondrially encoded cytochrome b (CYTB) gene, including 323 horses from 13 Chinese indigenous breeds and 84 reference sequences from GenBank. A total of 114 haplotypes were identified, of which 73 appeared among the 13 Chinese horse breeds. The high mitochondrially encoded cytochrome b haplotypic diversity suggests multiple maternal origins in Chinese horses.
Assuntos
Citocromos b/genética , DNA Mitocondrial/genética , Cavalos/genética , Filogenia , Animais , Sequência de Bases , China , Feminino , Haplótipos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Polimorfismo Genético , Alinhamento de SequênciaRESUMO
The paternal origins of Thoroughbred racehorses trace back to a handful of Middle Eastern stallions, imported to the British Isles during the seventeenth century. Yet, few details of the foundation mares were recorded, in many cases not even their names (several different maternal lineages trace back to 'A Royal Mare'). This has fuelled intense speculation over their origins. We examined mitochondrial DNA from 1929 horses to determine the origin of Thoroughbred foundation mares. There is no evidence to support exclusive Arab maternal origins as some historical records have suggested, or a significant importation of Oriental mares (the term used in historic records to refer to Middle East and western Asian breeds including Arab, Akhal-Teke, Barb and Caspian). Instead, we show that Thoroughbred foundation mares had a cosmopolitan European heritage with a far greater contribution from British and Irish Native mares than previously recognized.
Assuntos
Cruzamento , Cavalos/genética , Linhagem , Animais , DNA Mitocondrial/química , Feminino , Frequência do Gene , Variação Genética , Haplótipos , Irlanda , Masculino , Oriente Médio , Reino UnidoRESUMO
The origins of the domestic water buffalo remain contentious. To better understand the origins of Chinese water buffalo, we sequenced the complete mitochondrial cytochrome b (MT-CYB) gene from 270 individuals representing 13 Chinese domestic swamp buffalo populations. We found genetic evidence of introgression of river buffalo into Chinese swamp buffalo herds. Swamp buffalo haplotypes can be divided into two highly divergent lineages (A and B), suggesting that Chinese native swamp buffalo have two maternal origins. We found that the AâG transition in the buffalo MT-CYB gene stop codon resulted in buffalo haplotypes being terminated by one of two stop codons: AGA or AGG. AGA is common to river buffalo and lineage A of swamp buffalo, while AGG is specific to lineage B of swamp buffalo. Lineage A appears to have been domesticated in China. Further genetic evidence is required to clarify the origins of lineage B.
Assuntos
Búfalos/genética , Grupo dos Citocromos b/genética , DNA Mitocondrial/genética , Variação Genética , Filogenia , Animais , Sequência de Bases , China , Análise por Conglomerados , Primers do DNA/genética , Haplótipos/genética , Modelos Genéticos , Dados de Sequência Molecular , Análise de Sequência de DNARESUMO
The clustering software Structure has been used extensively to infer population structure in natural populations from multilocus genotype data. Determining meaningful values of K, the assumed number of subpopulations is one of the primary challenges of making biological inferences from Structure data. The package CorrSieve summarizes Structure output and performs a number of tests, including both previously reported methods and novel ones, to help determine meaningful values of K.