Fertile Crescent | EPFL Graph Search

The Fertile Crescent (الهلال الخصيب, הסהר הפורה) is a crescent-shaped region in the Middle East, spanning modern-day Iraq, Syria, Lebanon, Israel, Palestine and Jordan, together with the northern region of Kuwait, southeastern region of Turkey and the western portion of Iran. Some authors also include Cyprus and Northern Egypt. The Fertile Crescent is believed to be the very first region where settled farming emerged as people started the process of clearance and modification of natural vegetation to grow newly domesticated plants as crops. Early human civilizations such as Sumer in Mesopotamia flourished as a result. Technological advances in the region include the development of agriculture and the use of irrigation, of writing, the wheel, and glass, most emerging first in Mesopotamia. Terminology The term "Fertile Crescent" was popularized by archaeologist James Henry Breasted in Outlines of European History (1914) and Ancient Times, A History of the Early World (191

Nutrient limitations induced by drought affect forage N and P differently in two permanent grasslands

Alexandre Buttler, Claire Emilie Deléglise, Pierre Rémi Mariotte, Amarante Vitra

Drought events can strongly affect ecosystem functioning by modifying relationship between plants, microbes and soil chemistry, with consequent impacts on nutrient cycling. However, the potential impacts of a soil moisture reduction on the nitrogen (N) and phosphorus (P) cycling in grasslands remain poorly understood, especially in regard to. forage production. To fill this knowledge gap, a drought experiment was carried out using rainout shelters in two permanent grasslands, characterized by similar vegetation communities but contrasted soil nutrient limitations. Drought treatments were applied during two months, either when plant growth was highest (Early-season drought) or after the peak of biomass production (Late-season drought). Dry matter production, forage N status (NNI) and P content as well as N and P contents in microbial biomass and soil were determined. Both early and late-season drought significantly reduced soil moisture during the vegetation growth period. Forage yield was also reduced by drought, but only when it occurred late in the season. Using a structural equation model, we showed that soil moisture reduction had a direct effect on forage N status, suggesting that water shortage induced lower transpiration and water fluxes. Soil moisture reduction also affected forage P by reducing the availability of soil P. However, other mechanisms played a larger role and were site-specific. At the more fertile site, reduction in soil moisture directly impaired forage P, suggesting that water stress mainly resulted in lower diffusion rates to roots, while at the less fertile site, an indirect reduction of forage P through a pathway implying microbes (decrease in microbial P) was detected. Our results suggest that the two grasslands suffered mainly from water shortage per se, but also from drought induced nutrient deficiency (mainly P), which amplified yield losses and further decreased forage quality. Overall, our findings emphasize the need for further research on the plant-soil-microbe system functioning, in order to secure a sustainable and resilient forage production in the context of climate change.

ELSEVIER2019

Convergent genomic signatures of domestication in sheep and goats

Stéphane Joost, Pierre Taberlet

The evolutionary basis of domestication has been a longstanding question and its genetic architecture is becoming more tractable as more domestic species become genome-enabled. Before becoming established worldwide, sheep and goats were domesticated in the fertile crescent 10,500 years before present (YBP) where their wild relatives remain. Here we sequence the genomes of wild Asiatic mouflon and Bezoar ibex in the sheep and goat domestication center and compare their genomes with that of domestics from local, traditional, and improved breeds. Among the genomic regions carrying selective sweeps differentiating domestic breeds from wild populations, which are associated among others to genes involved in nervous system, immunity and productivity traits, 20 are common to Capra and Ovis. The patterns of selection vary between species, suggesting that while common targets of selection related to domestication and improvement exist, different solutions have arisen to achieve similar phenotypic end-points within these closely related livestock species.

Nature Publishing Group2018

Genome-wide SNP profiling of worldwide goat populations reveals strong partitioning of diversity and highlights post-domestication migration routes

Stéphane Joost, Estelle Rochat, Elia Vajana

Background: Goat populations that are characterized within the AdaptMap project cover a large part of the worldwide distribution of this species and provide the opportunity to assess their diversity at a global scale. We analysed genome-wide 50K single nucleotide polymorphism (SNP) data from 144 populations to describe the global patterns of molecular variation, compare them to those observed in other livestock species, and identify the drivers that led to the current distribution of goats. Results: A high degree of genetic variability exists among the goat populations studied. Our results highlight a strong partitioning of molecular diversity between and within continents. Three major gene pools correspond to goats from Europe, Africa and West Asia. Dissection of sub-structures disclosed regional gene pools, which reflect the main post-domestication migration routes. We also identified several exchanges, mainly in African populations, and which often involve admixed and cosmopolitan breeds. Extensive gene flow has taken place within specific areas (e.g., south Europe, Morocco and Mali-Burkina Faso-Nigeria), whereas elsewhere isolation due to geographical barriers (e.g., seas or mountains) or human management has decreased local gene flows. Conclusions: After domestication in the Fertile Crescent in the early Neolithic era (ca. 12,000 YBP), domestic goats that already carried differentiated gene pools spread to Europe, Africa and Asia. The spread of these populations determined the major genomic background of the continental populations, which currently have a more marked subdivision than that observed in other ruminant livestock species. Subsequently, further diversification occurred at the regional level due to geographical and reproductive isolation, which was accompanied by additional migrations and/or importations, the traces of which are still detectable today. The effects of breed formation were clearly detected, particularly in Central and North Europe. Overall, our results highlight a remarkable diversity that occurs at the global scale and is locally partitioned and often affected by introgression from cosmopolitan breeds. These findings support the importance of long-term preservation of goat diversity, and provide a useful framework for investigating adaptive introgression, directing genetic improvement and choosing breeding targets.

BMC2018