陕北高原蝗虫资源调查及区系分析

经调查，陕北高原共计蝗虫2总科8科14亚科27属51种(亚种)，其中对陕北地区农牧业危害严重的属有小车蝗属、星翅蝗属、负蝗属、尖翅蝗属、疣蝗属、稻蝗属等；对陕北高原蝗虫区系进行分析，结果表明：古北种为43种，占84．31％；东洋种1种，占1．96％；广布种为7种，占13．73％。标本保存于河北大学博物馆。     

The effects of human population structure on large genetic association studies

Large-scale association studies hold substantial promise for unraveling the genetic basis of common human diseases. A well-known problem with such studies is the presence of undetected population structure, which can lead to both false positive results and failures to detect genuine associations. Here we examine approximately 15,000 genome-wide single-nucleotide polymorphisms typed in three population groups to assess the consequences of population structure on the coming generation of association studies. The consequences of population structure on association outcomes increase markedly with sample size. For the size of study needed to detect typical genetic effects in common diseases, even the modest levels of population structure within population groups cannot safely be ignored. We also examine one method for correcting for population structure (Genomic Control). Although it often performs well, it may not correct for structure if too few loci are used and may overcorrect in other settings, leading to substantial loss of power. The results of our analysis can guide the design of large-scale association studies.