Dataset Information

Genomic analysis of 10 years of artificial selection in community-based breeding programs in two Ethiopian indigenous sheep breeds.

ABSTRACT: In recent times, community-based breeding programs (CBBPs) have been advocated as the best strategy for genetic improvement of local breeds in smallholder farms in developing countries. Since 2009, CBBPs have been implemented for Ethiopian Bonga and Menz sheep to improve growth rates resulting in significant genetic gains in 6-month weights. With the hypothesis that selection could be impacting their genomes, we systematically screened for possible genome changes in the two breeds by analyzing 600K BeadChip genotype data of 151 individuals (with the highest breeding values for 6-month weights) from CBBP flocks against 98 individuals from non-CBBP flocks. We observed no differences in genetic diversity and demographic dynamics between CBBP and non-CBBP flocks. Selection signature analysis employing ROH, logistic regression genome-wide association study , F_ST , XP-EHH and iHS revealed 5 (Bonga) and 11 (Menz) overlapping regions under selection, that co-localized with QTLs for production (body size/weight, growth, milk yield), meat/milk quality, and health/parasite resistance, suggesting that the decade-long selection has likely started to impact their genomes. However, genome-wide genetic differentiation between the CBBP and non-CBBP flocks is not yet clearly evident.

SUBMITTER: Rekik E

PROVIDER: S-EPMC10138745 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Genomic analysis of 10 years of artificial selection in community-based breeding programs in two Ethiopian indigenous sheep breeds.

Rekik Emna E Ahbara Abulgasim M AM Abate Zelalem Z Goshme Shenkute S Getachew Tesfaye T Haile Aynalem A Rischkowsky Barbara B Mwacharo Joram M JM

Animal genetics 20220415 3

In recent times, community-based breeding programs (CBBPs) have been advocated as the best strategy for genetic improvement of local breeds in smallholder farms in developing countries. Since 2009, CBBPs have been implemented for Ethiopian Bonga and Menz sheep to improve growth rates resulting in significant genetic gains in 6-month weights. With the hypothesis that selection could be impacting their genomes, we systematically screened for possible genome changes in the two breeds by analyzing 6 ...[more]

PMID: 35428998

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Project description:Indigenous breeds develop their own genomic characteristics by adapting to local environments or cultures over long periods of time. Most of them are not particularly productive in commercial terms, but they have abilities to survive in harsh environments or tolerate to specific diseases. Their adaptive characteristics play an important role as genetic materials for improving commercial breeds. As a step toward this goal, we analyzed the genome of Korean indigenous goats within 10 goat breeds. We collected 136 goat individuals by sequencing 46 new goats and employing 90 publicly available goats. Our whole-genome data was comprised of three indigenous breeds (Korean indigenous goat, Iranian indigenous goat, and Moroccan indigenous goat; n = 29, 18, 20), six commercial breeds (Saanen, Boer, Anglo-Nubian, British Alpine, Alpine, and Korean crossbred; n = 16, 11, 5, 5, 2, 13), and their ancestral species (Capra aegagrus; n = 17). We identified that the Iranian indigenous goat and the Moroccan indigenous goat have relatively similar genomic characteristics within a large category of genomic diversity but found that the Korean indigenous goat has unique genomic characteristics distinguished from the other nine breeds. Through population analysis, we confirmed that these characteristics have resulted from a near-isolated environment with strong genetic drift. The Korean indigenous goat experienced a severe genetic bottleneck upon entering the Korean Peninsula about 2,000 years ago, and has subsequently rarely experienced genetic interactions with other goat breeds. From selection analysis and gene-set enrichment analysis, we revealed selection signals for Salmonella infection and cardiomyopathy in the genome of the Korean indigenous goat. These adaptive characteristics were further identified with genomic-based evidence. We uncovered genomic regions of selective sweeps in the LBP and BPI genes (Salmonella infection) and the TTN and ITGB6 genes (cardiomyopathy), among several candidate genes. Our research presents unique genomic characteristics and distinctive selection signals of the Korean indigenous goat based on the extensive comparison. Although the adaptive traits require further validation through biological experiments, our findings are expected to provide a direction for future biodiversity conservation strategies and to contribute another option to genomic-based breeding programmes for improving the viability of Capra hircus.

Project description:BackgroundOptimum contribution selection (OCS) is effective for increasing genetic gain, controlling the rate of inbreeding and enables maintenance of genetic diversity. However, this diversity may be caused by high migrant contributions (MC) in the population due to introgression of genetic material from other breeds, which can threaten the conservation of small local populations. Therefore, breeding objectives should not only focus on increasing genetic gains but also on maintaining genetic originality and diversity of native alleles. This study aimed at investigating whether OCS was improved by including MC and modified kinships that account for breed origin of alleles. Three objective functions were considered for minimizing kinship, minimizing MC and maximizing genetic gain in the offspring generation, and we investigated their effects on German Angler and Vorderwald cattle.ResultsIn most scenarios, the results were similar for Angler and Vorderwald cattle. A significant positive correlation between MC and estimated breeding values of the selection candidates was observed for both breeds, thus traditional OCS would increase MC. Optimization was performed under the condition that the rate of inbreeding did not exceed 1% and at least 30% of the maximum progress was achieved for all other criteria. Although traditional OCS provided the highest breeding values under restriction of classical kinship, the magnitude of MC in the progeny generation was not controlled. When MC were constrained or minimized, the kinship at native alleles increased compared to the reference scenario. Thus, in addition to constraining MC, constraining kinship at native alleles is required to ensure that native genetic diversity is maintained. When kinship at native alleles was constrained, the classical kinship was automatically lowered in most cases and more sires were selected. However, the average breeding value in the next generation was also lower than that obtained with traditional OCS.ConclusionsFor local breeds with historical introgressions, current breeding programs should focus on increasing genetic gain and controlling inbreeding, as well as maintaining the genetic originality of the breeds and the diversity of native alleles via the inclusion of MC and kinship at native alleles in the OCS process.

Project description:BackgroundIn Ethiopia, livestock contributes 45% of agricultural GDP. Despite the economic role played by the sector, there have been little efforts to genetically improve the indigenous cattle. Morphological characterization of selected Ethiopian indigenous cattle has been made for (Bonga, Jimma, and Kerayu) cattle types. But, the selected indigenous cattle were not characterized at molecular level (genetic diversity information). Hence, this work was initiated to detect and determine the genetic diversity and population structure of selected Ethiopian indigenous cattle ecotypes using microsatellite markers.ResultsDifferent alleles were identified (131) and thirty-three of these alleles were unique to specific ecotypes. All loci used were informative with PIC values ranging from 0.5 (TGLA126) to 0.84 (ETH10) with a mean of 0.70 per locus. The Shannon information index ranged from (I = 1.02) ILST006 to (I = 1.63) ETH10 with an average of 1.28 revealing there is genetic diversity. Moreover, analysis of molecular variance (AMOVA) revealed 84% genetic variation within a population and 13% variation among populations. The value of F-statistics (Fst) (0.129 = 13%) indicated that there was moderate genetic differentiation among ecotypes. The (UPGMA) revealed, Bonga and Jimma clustered together while Kerayu cattle were relatively distinct, Principal coordinates analysis (PCOA) and structure analysis grouped the individual into different clusters confirming the presence of ecotype admixture due to geographical origins and uncontrolled mating.ConclusionIn general, this study has successfully characterized the genetic diversity and population structure of Bonga, Jimma, and Kerayu cattle ecotypes using high polymorphic/informative microsatellite markers. According to this study, Kerayu cattle have high AR and PA when compared to Bonga and Jimma cattle populations. So, the Kerayu population is more diverse than others and it is the hotspot for genetic diversity study. The generated information is very relevant for breeder and genetic conservation.

Dataset Information

Genomic analysis of 10 years of artificial selection in community-based breeding programs in two Ethiopian indigenous sheep breeds.

Publications

Genomic analysis of 10 years of artificial selection in community-based breeding programs in two Ethiopian indigenous sheep breeds.

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