Accuracy Assessment of Multi-Source Gridded Population Distribution Datasets in China

Population is one of the core elements of sustainable development. Quantifying the estimation accuracy of population spatial distribution has been recognized as a critical and challenging task. This study aims to evaluate the data accuracy of four population datasets in China, including three global gridded population datasets, the Gridded Population of the World (GPW), Global Rural and Urban Mapping Project (GRUMP), and WorldPop project (WorldPop), and a Chinese regional gridded population dataset, the China 1 km Gridded Population (CnPop) dataset. These datasets are assessed using a specific method based on a GIS-linked 2000 census dataset at the township level in China. The results indicate that WorldPop had the highest estimation accuracy, estimating about 60% of the total population. CnPop accurately estimated about half of the total population, showing a good mapping performance. The GPW had an acceptable estimation accuracy in a few plain and basin areas, accounting for about 30% of the total population. Compared to the GPW, GRUMP accurately estimated about 40% of the total population. The relative estimation error analysis discovered the disadvantages of the generation strategies of these datasets. The conclusions are expected to serve as a quality reference for potential dataset users and producers, and promote accuracy assessment for population datasets in other regions and globally

A selfish genetic element confers non-Mendelian inheritance in rice

Selfish genetic elements are pervasive in eukaryote genomes, but their role remains controversial. We show that qHMSZ a major quantitative genetic locus for hybrid male sterility between wild rice (Oryza meridionalis) and Asian cultivated rice (O. sativa), contains two tightly linked genes [Open Reading Frame 2 (ORF2) and ORF3]. ORF2 encodes a toxic genetic element that aborts pollen in a sporophytic manner, whereas ORF3 encodes an antidote that protects pollen in a gametophytic manner. Pollens lacking ORF3 are selectively eliminated, leading to segregation distortion in the progeny. Analysis of the genetic sequence suggests that ORF3 arose first, followed by gradual functionalization of ORF2. Furthermore, this toxin-antidote system may have promoted the differentiation and/or maintained the genome stability of wild and cultivated rice