Dataset Information

Genomic scan of selective sweeps in Djallonke (West African Dwarf) sheep shed light on adaptation to harsh environments.

ABSTRACT: The Djallonké (West African Dwarf) sheep is a small-sized haired sheep resulting from a costly evolutionary process of natural adaptation to the harsh environment of West Africa including trypanosome challenge. However, genomic studies carried out in this sheep are scant. In this research, genomic data of 184 Djallonké sheep (and 12 Burkina-Sahel sheep as an outgroup) generated using medium-density SNP Chips were analyzed. Three different statistics (iHS, XP-EHH and nSL) were applied to identify candidate selection sweep regions spanning genes putatively associated with adaptation of sheep to the West African environment. A total of 207 candidate selection sweep regions were defined. Gene-annotation enrichment and functional annotation analyses allowed to identify three statistically significant functional clusters involving 12 candidate genes. Genes included in Functional Clusters associated to selection signatures were mainly related to metabolic response to stress, including regulation of oxidative and metabolic stress and thermotolerance. The bovine chromosomal areas carrying QTLs for cattle trypanotolerance were compared with the regions on which the orthologous functional candidate cattle genes were located. The importance of cattle BTA4 for trypanotolerant response might have been conserved between species. The current research provides new insights on the genomic basis for adaptation and highlights the importance of obtaining information from non-cosmopolite livestock populations managed in harsh environments.

SUBMITTER: Alvarez I

PROVIDER: S-EPMC7028950 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Genomic scan of selective sweeps in Djallonké (West African Dwarf) sheep shed light on adaptation to harsh environments.

Álvarez Isabel I Fernández Iván I Traoré Amadou A Pérez-Pardal Lucía L Menéndez-Arias Nuria A NA Goyache Félix F

Scientific reports 20200218 1

The Djallonké (West African Dwarf) sheep is a small-sized haired sheep resulting from a costly evolutionary process of natural adaptation to the harsh environment of West Africa including trypanosome challenge. However, genomic studies carried out in this sheep are scant. In this research, genomic data of 184 Djallonké sheep (and 12 Burkina-Sahel sheep as an outgroup) generated using medium-density SNP Chips were analyzed. Three different statistics (iHS, XP-EHH and nSL) were applied to identify ...[more]

PMID: 32071365

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Project description:BackgroundThe present study aimed at characterizing the Djallonké Sheep (DS), the only local sheep breed raised in Guinea-Bissau. A total of 200 animals were sampled from four regions (Bafatá, Gabú, Oio and Cacheu) and described using 7 visual criteria and 8 measurements. These parameters have been studied by principal components analysis. The genetic diversity and population structure of 92 unrelated animals were studied using 12 microsatellite markers.ResultsThe values of quantitative characters in the Bafatá region were significantly higher than those obtained in the other three regions. A phenotypic diversity of the DS population was observed and three genetic types distinguished: animals with "large traits" in the region of Bafatá, animals with "intermediate traits" in the regions of Gabú and Oio and animals with "small traits" in the Cacheu region. The hair coat colors are dominated by the white color, the shape of the facial head profile is mainly convex and the ears "erected horizontally". Most of the morphobiometric characteristics were significantly influenced by the "region" and "sex of animals". The average Polymorphism Information Content (PIC) of 0.65 ± 0.11 supports the use of markers in genetic characterization. Gabú subpopulation had the highest genetic diversity measures (He = 0.716 ± 0.089) while Cacheu DS subpopulation presented the smallest (He = 0.651 ± 0.157). Only Gabú and Bafatá subpopulations presented significant heterozygote deficiency across all loci indicating possible significant inbreeding. Mean values for FIT, FST, FIS and GST statistics across all loci were 0.09, 0.029, 0.063 and 0.043 respectively. The overall genetic differentiation observed between the four DS subpopulations studied was low. Bafatá and Gabú are the most closely related subpopulations (DS = 0.04, genetic identity = 0.96) while Bafatá and Cacheu were the most genetically distant subpopulations (DS = 0.14, genetic identity = 0.87). Using Bayesian approach, the number of K groups that best fit the data is detected between 2 and 3, which is consistent with the morphological analysis and the factorial analysis of correspondence.ConclusionsThe molecular results on DS population of Guinea-Bissau confirmed the ones obtained with morphological analysis. The three genetic types observed phenotypically might be due to a combination of the agro-ecological differences and the management of breeding rather than genetic factors.

Project description:BackgroundAdaptive evolution is one of the crucial mechanisms for organisms to survive and thrive in new environments. Recent studies suggest that adaptive evolution could rapidly occur in species to respond to novel environments or environmental challenges during range expansion. However, for environmental adaptation, many studies successfully detected phenotypic features associated with local environments, but did not provide ample genetic evidence on microevolutionary dynamics. It is therefore crucial to thoroughly investigate the genetic basis of rapid microevolution in response to environmental changes, in particular on what genes and associated variation are responsible for environmental challenges. Here, we genotyped genome-wide gene-associated microsatellites to detect genetic signatures of rapid microevolution of a marine tunicate invader, Ciona robusta, during recent range expansion to the harsh environment in the Red Sea.ResultsThe Red Sea population was significantly differentiated from the other global populations. The genome-wide scan, as well as multiple analytical methods, successfully identified a set of adaptive genes. Interestingly, the allele frequency largely varied at several adaptive loci in the Red Sea population, and we found significant correlations between allele frequency and local environmental factors at these adaptive loci. Furthermore, a set of genes were annotated to get involved in local temperature and salinity adaptation, and the identified adaptive genes may largely contribute to the invasion success to harsh environments.ConclusionsAll the evidence obtained in this study clearly showed that environment-driven selection had left detectable signatures in the genome of Ciona robusta within a few generations. Such a rapid microevolutionary process is largely responsible for the harsh environmental adaptation and therefore contributes to invasion success in different aquatic ecosystems with largely varied environmental factors.

Dataset Information

Genomic scan of selective sweeps in Djallonke (West African Dwarf) sheep shed light on adaptation to harsh environments.

Publications

Genomic scan of selective sweeps in Djallonké (West African Dwarf) sheep shed light on adaptation to harsh environments.

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