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A guinea fowl genome assembly provides new evidence on evolution following domestication and selection in galliformes.

ABSTRACT: The helmeted guinea fowl Numida meleagris belongs to the order Galliformes. Its natural range includes a large part of sub-Saharan Africa, from Senegal to Eritrea and from Chad to South Africa. Archaeozoological and artistic evidence suggest domestication of this species may have occurred about 2,000 years BP in Mali and Sudan primarily as a food resource, although villagers also benefit from its capacity to give loud alarm calls in case of danger, of its ability to consume parasites such as ticks and to hunt snakes, thus suggesting its domestication may have resulted from a commensal association process. Today, it is still farmed in Africa, mainly as a traditional village poultry, and is also bred more intensively in other countries, mainly France and Italy. The lack of available molecular genetic markers has limited the genetic studies conducted to date on guinea fowl. We present here a first-generation whole-genome sequence draft assembly used as a reference for a study by a Pool-seq approach of wild and domestic populations from Europe and Africa. We show that the domestic populations share a higher genetic similarity between each other than they do to wild populations living in the same geographical area. Several genomic regions showing selection signatures putatively related to domestication or importation to Europe were detected, containing candidate genes, most notably EDNRB2, possibly explaining losses in plumage coloration phenotypes in domesticated populations.

SUBMITTER: Vignal A

PROVIDER: S-EPMC6579635 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND: Domestication of chicken is believed to have occurred in Southeast Asia, especially in Indus valley. However, non-inclusion of Indian red jungle fowl (RJF), Gallus gallus murghi in previous studies has left a big gap in understanding the relationship of this major group of birds. In the present study, we addressed this issue by analyzing 76 Indian birds that included 56 G. g. murghi (RJF), 16 G. g. domesticus (domestic chicken) and 4 G. sonneratii (Grey JF) using both microsatellite markers and mitochondrial D-loop sequences. We also compared the D-loop sequences of Indian birds with those of 779 birds obtained from GenBank. RESULTS: Microsatellite marker analyses of Indian birds indicated an average FST of 0.126 within G. g. murghi, and 0.154 within G. g. domesticus while it was more than 0.2 between the two groups. The microsatellite-based phylogenetic trees showed a clear separation of G. g. domesticus from G. g. murghi, and G. sonneratii. Mitochondrial DNA based mismatch distribution analyses showed a lower Harpending's raggedness index in both G. g. murghi (0.001515) and in Indian G. g. domesticus (0.0149) birds indicating population expansion. When meta analysis of global populations of 855 birds was carried out using median joining haplotype network, 43 Indian birds of G. g. domesticus (19 haplotypes) were distributed throughout the network sharing haplotypes with the RJFs of different origins. CONCLUSION: Our results suggest that the domestication of chicken has occurred independently in different locations of Asia including India. We found evidence for domestication of Indian birds from G. g. spadiceus and G. g. gallus as well as from G. g. murghi, corroborating multiple domestication of Indian and other domestic chicken. In contrast to the commonly held view that RJF and domestic birds hybridize in nature, the present study shows that G. g. murghi is relatively pure. Further, the study also suggested that the chicken populations have undergone population expansion, especially in the Indus valley.

Project description:BackgroundPolymorphism in the pfcrt gene underlies Plasmodium falciparum chloroquine resistance (CQR), as sensitive strains consistently carry lysine (K), while CQR strains carry threonine (T) at the codon 76. Previous studies have shown that microsatellite (MS) haplotype variation can be used to study the evolution of CQR polymorphism and to characterize intra- and inter-population dispersal of CQR in Papua New Guinea (PNG).MethodsHere, following identification of new polymorphic MS in introns 2 and 3 within the pfcrt gene (msint2 and msint3, respectively), locus-by-locus and haplotype heterozygosity (H) analyses were performed to determine the distribution of this intronic polymorphism among pfcrt chloroquine-sensitive and CQR alleles.ResultsFor MS flanking the pfcrt CQR allele, H ranged from 0.07 (B5M77, -18 kb) to 0.094 (9B12, +2 kb) suggesting that CQ selection pressure was responsible for strong homogenisation of this gene locus. In a survey of 206 pfcrt-SVMNT allele-containing field samples from malaria-endemic regions of PNG, H for msint2 was 0.201. This observation suggests that pfcrt msint2 exhibits a higher level of diversity than what is expected from the analyses of pfcrt flanking MS. Further analyses showed that one of the three haplotypes present in the early 1980's samples has become the predominant haplotype (frequency = 0.901) in CQR parasite populations collected after 1995 from three PNG sites, when CQR had spread throughout malaria-endemic regions of PNG. Apparent localized diversification of pfcrt haplotypes at each site was also observed among samples collected after 1995, where minor CQR-associated haplotypes were found to be unique to each site.ConclusionIn this study, a higher level of diversity at MS loci within the pfcrt gene was observed when compared with the level of diversity at pfcrt flanking MS. While pfcrt (K76T) and its immediate flanking region indicate homogenisation in PNG CQR parasite populations, pfcrt intronic MS variation provides evidence that the locus is still evolving. Further studies are needed to determine whether these intronic MS introduce the underlying genetic mechanisms that may generate pfcrt allelic diversity.

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Project description:BACKGROUND: During the Neolithic revolution, early farmers altered plant development to domesticate crops. Similar traits were often selected independently in different wild species; yet the genetic basis of this parallel phenotypic evolution remains elusive. Plant architecture ranks among these target traits composing the domestication syndrome. We focused on the reduction of branching which occurred in several cereals, an adaptation known to rely on the major gene Teosinte-branched1 (Tb1) in maize. We investigate the role of the Tb1 orthologue (Pgtb1) in the domestication of pearl millet (Pennisetum glaucum), an African outcrossing cereal. METHODOLOGY/PRINCIPAL FINDINGS: Gene cloning, expression profiling, QTL mapping and molecular evolution analysis were combined in a comparative approach between pearl millet and maize. Our results in pearl millet support a role for PgTb1 in domestication despite important differences in the genetic basis of branching adaptation in that species compared to maize (e.g. weaker effects of PgTb1). Genetic maps suggest this pattern to be consistent in other cereals with reduced branching (e.g. sorghum, foxtail millet). Moreover, although the adaptive sites underlying domestication were not formerly identified, signatures of selection pointed to putative regulatory regions upstream of both Tb1 orthologues in maize and pearl millet. However, the signature of human selection in the pearl millet Tb1 is much weaker in pearl millet than in maize. CONCLUSIONS/SIGNIFICANCE: Our results suggest that some level of parallel evolution involved at least regions directly upstream of Tb1 for the domestication of pearl millet and maize. This was unanticipated given the multigenic basis of domestication traits and the divergence of wild progenitor species for over 30 million years prior to human selection. We also hypothesized that regular introgression of domestic pearl millet phenotypes by genes from the wild gene pool could explain why the selective sweep in pearl millet is softer than in maize.

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A guinea fowl genome assembly provides new evidence on evolution following domestication and selection in galliformes.

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