Haplotype affinities resolve a major component of goat (Capra hircus) MtDNA D-loop diversity and reveal specific features of the Sardinian stock

Variations in Casein Genes Are Associated with Milk Protein and Fat Contents in Sarda Goats (Capra hircus), with an Important Role of CSN1S2 for Milk Yield

This work aimed to assess the variability of casein genes in a population of 153 bucks and 825 lactating does of the Sarda breed, and to perform association analysis between polymorphic sites and milk yield and composition traits. To genotype the casein genes, we chose an SNP panel including 44 SNPs mapping to the four casein genes CSN1S1, CSN2, CSN1S2, and CSN3. Genotyping (made by KASP™ genotyping assay, based on competitive allele-specific PCR) revealed the high variability of the Sarda goat, and haplotype analysis revealed linkage disequilibrium (LD) between CSN1S1 and CSN2 genes, in addition to two LD blocks within the CSN1S2 and two LD blocks within the CSN3 gene, in bucks and does. Association analysis revealed that variability at all four casein genes was associated with milk protein content, total solids, and milk energy. The three Ca-sensitive casein genes were associated with lipid content, and CSN1S2 showed a unique pattern, with intron variants associated with milk yield, in addition to milk pH, NaCl, and SCS (Somatic Cell Score). This information might prove useful in selection schemes and in future investigations aiming to better understand the biology of lactation, and the direct link between genotype and phenotype.

Ecogroups and maternal haplogroups reveal the ancestral origin of native Chinese goat populations based on the variation of mtDNA D-loop sequences

China is rich in goat breeding resources. Officially recognized local goat breeds are mainly distributed in agro-ecological regions. The population structure and matrilineal origin of native Chinese goats can be used to formulate protection and utilization strategies for these genetic resources. In this study, the genetic structure and maternal origin of native Chinese goats were investigated using mtDNA D-loop sequences. A total of 329 goat samples from 25 Chinese indigenous goat populations and five introduced goat breeds from abroad were collected; these populations were distributed in four ecogroups designated as Southwest, South-central, the North China Plain, and Foreign-ecogroup. A larger average number of nucleotide differences and richer nucleotide diversity were observed in South-central and Foreign-ecogroup, whereas these were lower in Southwest. The 216 haplotypes divided into several haplogroups, of which HapA contained 99 haplotypes distributed in Southwest, the North China Plain, and Foreign-ecogroup with high frequency (0.53-0.77), whereas the frequency of HapA in South-central was <0.09. HapB was mostly found in South-central (0.5538) and was distributed to the North China Plain (0.2667), while it was rare in Southwest (<0.08) and Foreign-ecogroup (<0.07). According to the estimation of kinship and ancestry, HapA had five ancestors (A2, A3, A5, A10, and A12), HapB had a single maternal ancestor (A8), and HapC had two maternal ancestors (A1 and A4). This study showed that native Chinese goat breeds were mainly divided into three haplogroups (HapA, HapB, and HapC) and goat populations have expanded in the ecological regions.

Assessing the Diversity and Population Substructure of Sarda Breed Bucks by Using Mtdna and Y-Chromosome Markers

A sample of 146 Sarda bucks from eight subregions of Sardinia, Italy (Nuorese, Barbagia, Baronia, Ogliastra, Sarrabus, Guspinese, Iglesiente, Sulcis) were characterized for Y-chromosome and mtDNA markers to assess the levels of population substructure. Five polymorphic loci (SRY, AMELY, ZFY, and DDX3Y) on the Y-chromosome were genotyped. The control region of mtDNA was sequenced as a source of complementary information. Analysis of Y-chromosome data revealed the segregation of 5 haplotypes: Y1A (66.43%), Y2 (28.57%), Y1C (3.57%), Y1B1 (0.71%), and Y1B2 (0.71%). High levels of Y-chromosome diversity were observed in populations from Southwest Sardinia. The FST values based on Y-chromosome and mtDNA data were low, although a paternal genetic differentiation was observed when comparing the Nuorese and Barbagia populations (Central Sardinia) with the Sulcis, Iglesiente, and Sarrabus populations (Southern Sardinia). AMOVA analysis supported the lack of population substructure. These results suggest the occurrence of a historical and extensive gene flow between Sarda goat populations from different locations of Sardinia, despite the fact that this island is covered by several large mountain ranges. Introgression with foreign caprine breeds in order to improve milk production might have also contributed to avoiding the genetic differentiation amongst Sarda populations.

Maternal Origins and Haplotype Diversity of Seven Russian Goat Populations Based on the D-loop Sequence Variability

Simple Summary

Russia has diverse specifically selected and multipurpose goat resources. However, the origin of the local goats is still enigmatic. In this study, we sequenced and analyzed mitochondrial DNA (mtDNA) fragments of seven Russian local goat populations to provide the first insight into their maternal lineage.

Abstract

The territory of modern Russia lies on the crossroads of East and West and covers various geographical environments where diverse groups of local goats originated. In this work, we present the first study on the maternal origin of Russian local goats, including Altai Mountain (n = 9), Dagestan Downy (n = 18), Dagestan Local (n = 12), Dagestan Milk (n = 15), Karachaev (n = 21), Orenburg (n = 10), and Soviet Mohair (n = 7) breeds, based on 715 bp D-loop mitochondrial DNA (mtDNA) sequences. Saanen goats (n = 5) were used for comparison. Our findings reveal a high haplotype (HD = 0.843–1.000) and nucleotide diversity (π = 0.0112–0.0261). A total of 59 haplotypes were determined in the Russian goat breeds, in which all differed from the haplotypes of the Saanen goats. The haplotypes identified in Altai Mountain, Orenburg, Soviet Mohair, and Saanen goats were breed specific. Most haplotypes (56 of 59) were clustered together with samples belonging to haplogroup A, which was in accordance with the global genetic pattern of maternal origin seen in most goats worldwide. The haplotypes that were grouped together with rare haplogroups D and G were found in the Altai Mountain breed and haplogroup C was detected in the Soviet Mohair breed. Thus, our findings revealed that local goats might have been brought to Russia via various migration routes. In addition, haplotype sharing was found in aboriginal goat populations from overlapping regions, which might be useful information for their official recognition status.

Polymorphisms, differentiation, and phylogeny of 10 Tibetan goat populations inferred from mitochondrial D-loop sequences

China has abundant population of Tibetan goats, but available information regarding genetic structure and phylogenetic status remains limited. Here, 130 mitochondrial D-loop sequences of individuals from 10 Tibetan goat populations located in distinct plateau areas were analyzed. Eighty-six haplotypes were defined, among which 97.7% were group-specific haplotypes. Haplotype and nucleotide diversity indices were 0.990 ± 0.003 and 0.0145 ± 0.0013, respectively. The pairwise Wright's F-statistics ranged from -0.028 to 0.385, and over half of them were greater than 0.05, indicating apparent genetic differentiation among the populations. AMOVA analysis (F_ST = 0.0858) manifested that the genetic structure has become weak. Phylogenetic trees revealed four haplogroups (A, B, C, and D), suggesting that Tibetan goats had four origins. Mismatch distribution analyses and neutrality tests indicated that at least one population expansion event occurred during the demographic history of Tibetan goat. These results will provide a more complete understanding of Tibetan goat genetic resources.

Mitochondrial D-loop sequences reveal a mixture of endemism and immigration in Egyptian goat populations

The mitochondrial D-loop region was used to investigate genetic diversity within and between populations of Egyptian goats, to elucidate processes that explain present patterns of diversity and differentiation and to characterize Egyptian goats relative to international breeds. A total of 120 animals from six populations were sampled. Results confirm the main trend from previous studies of mtDNA diversity in goats, with high levels of diversity within populations, but with a comparative lack of genetic structure supporting geographic distribution. Haplotype diversity varied in a narrow range whereas nucleotide diversity values were more informative in showing differences between populations. The majority of goats analyzed (93.2%) displayed haplotypes that group with Haplogroup A, the most common type found in global goat populations. The remaining animals grouped with the less common Haplogroup G. Population differentiation analysis showed some uniqueness in the Aswan and Sharkawi populations from the South and East of Egypt. Overall, the structure of the Egyptian goat population is characterized by a high degree of homogeneity among populations from the north-western coastal region, the Nile Delta and the upper and middle regions of the Nile valley, but with possible introgression of rarer haplotypes into populations at the southern and eastern extremities of the country.

Whole mitochondrial genomes unveil the impact of domestication on goat matrilineal variability

Background

The current extensive use of the domestic goat (Capra hircus) is the result of its medium size and high adaptability as multiple breeds. The extent to which its genetic variability was influenced by early domestication practices is largely unknown. A common standard by which to analyze maternally-inherited variability of livestock species is through complete sequencing of the entire mitogenome (mitochondrial DNA, mtDNA).

Results

We present the first extensive survey of goat mitogenomic variability based on 84 complete sequences selected from an initial collection of 758 samples that represent 60 different breeds of C. hircus, as well as its wild sister species, bezoar (Capra aegagrus) from Iran. Our phylogenetic analyses dated the most recent common ancestor of C. hircus to ~460,000 years (ka) ago and identified five distinctive domestic haplogroups (A, B1, C1a, D1 and G). More than 90 % of goats examined were in haplogroup A. These domestic lineages are predominantly nested within C. aegagrus branches, diverged concomitantly at the interface between the Epipaleolithic and early Neolithic periods, and underwent a dramatic expansion starting from ~12–10 ka ago.

Conclusions

Domestic goat mitogenomes descended from a small number of founding haplotypes that underwent domestication after surviving the last glacial maximum in the Near Eastern refuges. All modern haplotypes A probably descended from a single (or at most a few closely related) female C. aegagrus. Zooarchaelogical data indicate that domestication first occurred in Southeastern Anatolia. Goats accompanying the first Neolithic migration waves into the Mediterranean were already characterized by two ancestral A and C variants. The ancient separation of the C branch (~130 ka ago) suggests a genetically distinct population that could have been involved in a second event of domestication. The novel diagnostic mutational motifs defined here, which distinguish wild and domestic haplogroups, could be used to understand phylogenetic relationships among modern breeds and ancient remains and to evaluate whether selection differentially affected mitochondrial genome variants during the development of economically important breeds.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2342-2) contains supplementary material, which is available to authorized users.

Phylogeny and patterns of diversity of goat mtDNA haplogroup A revealed by resequencing complete mitogenomes

We sequenced to near completion the entire mtDNA of 28 Sardinian goats, selected to represent the widest possible diversity of the most widespread mitochondrial evolutionary lineage, haplogroup (Hg) A. These specimens were reporters of the diversity in the island but also elsewhere, as inferred from their affiliation to each of 11 clades defined by D-loop variation. Two reference sequences completed the dataset. Overall, 206 variations were found in the full set of 30 sequences, of which 23 were protein-coding non-synonymous single nucleotide substitutions. Many polymorphic sites within Hg A were informative for the reconstruction of its internal phylogeny. Bayesian and network clustering revealed a general similarity over the entire molecule of sequences previously assigned to the same D-loop clade, indicating evolutionarily meaningful lineages. Two major sister groupings emerged within Hg A, which parallel distinct geographical distributions of D-loop clades in extant stocks. The pattern of variation in protein-coding genes revealed an overwhelming role of purifying selection, with the quota of surviving variants approaching neutrality. However, a simple model of relaxation of selection for the bulk of variants here reported should be rejected. Non-synonymous diversity of Hg's A, B and C denoted that a proportion of variants not greater than that allowed in the wild was given the opportunity to spread into domesticated stocks. Our results also confirmed that a remarkable proportion of pre-existing Hg A diversity became incorporated into domestic stocks. Our results confirm clade A11 as a well differentiated and ancient lineage peculiar of Sardinia.