Origins,timing and introgression of domestic geese revealed by whole genome data

Background Geese are among the most important poultry species in the world.The current generally accepted hypothesis is that the European domestic geese originated from greylag geese(Anser anser),and Chinese domestic geese have two origins,most of which originated from swan geese(Anser cygnoides),and the Yili goose originated from greylag geese.To explain the origin and demographic history of geese,we selected 14 goose breeds from Europe and China and wild populations of swan and greylag geese,and whole genome sequencing data were obtained for 74 samples.Results Population structure analysis and phylogenetic trees showed that the wild ancestor of Chinese domestic geese,except for Yili,is the swan geese,and the wild ancestor of Chinese Yili and European domestic geese is greylag geese.Analysis of the demographic history suggests that the domestication of Chinese geese occurred~3499 years ago and that of the European geese occurred~7552 years ago.Furthermore,gene flow was observed between domestic geese and their wild ancestors.Analysis of introgression showed that Yili geese had been introgressed by Chinese domestic geese,and the body size of Yili geese may be influenced by introgression events of some growthrelated genes,including IGF-1.Conclusions Our study provides evidence for the origin of geese at the genome-wide level and advances the understanding of the history of goose domestication and the traits affected by introgression events.

Dynamic tensile properties and microstructural evolution of extruded EW75 magnesium alloy at high strain rates

The dynamic tensile properties and microstructural evolution of an extruded EW75 magnesium alloy deformed at ambient temperature and different high strain rates(from 1000 to 3000 s^(-1))along extrusion direction(ED)were investigated by Split Hopkinson Tension Bar(SHTB).The corresponding deformation mechanisms,texture evolution and microstructure changes were analyzed by optical microscope(OM),electron backscatter diffraction(EBSD)and transmission electron microscope(TEM).The results show that the extruded EW75 magnesium alloy along ED exhibits a conventional positive strain rate sensitivity that the dynamic flow stresses increase with in creasing strain rate.Texture measurements show that after dynamic tension,the initial weak texture of extruded EW75 magnesium alloy tansforms to a relatively strong<10-10>//ED texture with increasing strain rates.The microstructural analysis demonstrates that dislocation motion are main deformatin mode to accommodate dynamic tensile deformation at high strain rates.In addition,the interactions of dislocation-dislocation and dislocation-second phase lead to the in crease of flow stress and strain hardening with increasing strain rate.

Pottery lipid analysis at the Shangzhai site,Beijing,and its implication for subsistence strategy

As the crossroads of prehistoric cultures,the Beijing region is an important area for studying the exchange of prehistoric culture and the spread of millet agriculture.Although millet remains have been found in the Donghulin site during the Early Neolithic Age,there is little millet remains during the Middle and Late Neolithic Age,so there is a gap of approximately2,000 years since the time of the Donghulin site.The Shangzhai site is located in the Pinggu Basin in eastern Beijing,and it has a large time span with sequential strata;however,there are few large animals and plant remains found at this site,thus the subsistence strategy of ancient people remains unclear.In this study,the absorbed lipids of pottery sherds unearthed in the Neolithic cultural layer of the Shangzhai site were extracted and analysed.The results show that these potteries were used to process millet,the meat of terrestrial non-ruminants and wild ruminants,and dairy of wild ruminants,providing new insights for the subsistence strategy and the development of millet agriculture in the Middle and Late Neolithic Age of Beijing.In addition,the food processing in pottery may be an internal heating method,such as stone boiling.

Starch grain evidence reveals early pottery function cooking plant foods in North China

Early pottery sherds excavated in northern China date back to more than 11,000 cal a BP,and are presumed to have been used as cooking vessels.There has been,however,no direct evidence to demonstrate this function.Here we report ancient starch grains recovered from carbonized residues adhering to the bases of flatbottomed vessels excavated from the Zhuannian site dating more than 10,000 cal a BP in the North China Plain.This evidence demonstrates that early pottery was being used to cook cereal grains,particularly millets,and acorns.Because millets were in the process of domestication at thistime,we propose that pottery invention in northern China may have been related to early farming activities.