Origin and diversification dynamics of self-incompatibility haplotypes, pp. 625–636
Camille Elsa Gervais, Vincent Castric, Adrienne Ressayre, and Sylvain Billiard
Self-incompatibility is widespread, having evolved in several hermaphrodite plant species to avoid inbreeding. It is controlled by two completely linked genes at the highly multiallelic S-locus. How do new alleles of these genes evolve? The results presented in this article show that the conditions that allow diversification are less stringent when stochasticity is taken into account. This suggests that diversification is indeed possible in an unstructured population.
Genetic variation and the fate of beneficial mutations in asexual populations, pp. 647–661
Gregory I. Lang, David Botstein, and Michael M. Desai
Evolutionary adaptation occurs via new mutations and selection on standing genetic variation. Current thinking views these as distinct, but this article shows that standing genetic variation and new mutations are fundamentally intertwined in experimental yeast populations. Even in initial clonal populations many new mutations quickly add to background variation, despite the presence of selection. The fate of individual beneficial mutations is shown to be almost independent of the benefit the mutations themselves confer, instead being primarily determined by where the mutation falls within the background variation.
A key temporal delay in the circadian cycle of Drosophila is mediated by a nuclear localization signal in the Timeless protein, pp. 591–600
Lino Saez, Mary Derasmo, Pablo Meyer, J. Stieglitz, and Michael W. Young
Regulated nuclear entry of the Period (PER) and Timeless (TIM) proteins is at the heart of the circadian clock mechanism. PER and TIM move from the cytoplasm to the nucleus daily, and the length of time they reside in the cytoplasm determines the length of the circadian period. This article shows that TIM is required for the nuclear localization of PER and points to a key role for the TIM nuclear localization signal in the regulated nuclear accumulation of both proteins.
Overcoming redundancy: An RNAi enhancer screen for morphogenesis genes in Caenorhabditis elegans, pp. 549–564
Jacob M. Sawyer, Stephanie Glass, Trudy Li, Gidi Shemer, Noor D. White, Natalia G. Starostina, Edward T. Kipreos, Corbin D. Jones, and Bob Goldstein
Redundancy presents a serious challenge to geneticists. Genetic mechanisms of morphogenesis in animal development appear especially susceptible to redundancy. These investigators developed a screening strategy to tackle this challenge to find genes that play key roles in Caenorhabditis elegans gastrulation. Their solution is to use a doublysensitized genetic background, to seek subtle defects in gastrulation captured on film, rather than depend on terminal phenotypes. The results reveal a set of genes that function in gastrulation, and highlight some general strategies for facing the challenge of redundancy.
Do large effect QTLs fractionate? A case study at the maize domestication QTL teosinte branched1, pp. 673–681
Anthony J. Studer and John F. Doebley
Do single large effect QTLs represent single genes? These authors performed two experiments to address this question for the large effect QTL at the teosinte branched1 (tb1) gene of maize. Their experiments indicate that the QTL for plant architecture traits at tb1 corresponds to a single gene, but the QTL for ear morphology traits fractionates into multiple linked QTL (genes). Thus, a single QTL does not necessarily mean a single gene.
Extensive and heritable epigenetic remodeling and genetic stability accompany allohexaploidization of wheat, pp. 499–509
Na Zhao, Bo Zhu, Mingjiu Li, Li Wang, Liying Xu, Huakun Zhang, Shuangshuang Zheng, Bao Qi, Fangpu Han, and Bao Liu
Allopolyploidy has played a prominent role in organismal evolution. It is associated with rapid genomic changes, but to what extent do those changes influence speciation? This article shows that rampant genetic instability associated with nascent allohexaploidization in wheat is likely incidental to speciation. Instead, extensive and heritable epigenetic remodeling coupled with preponderant genetic stability is more likely a contributory factor to speciation event(s).
This Month in the American Journal of Human Genetics
Rare variant association testing for sequencing data using the sequence kernel association test (SKAT), Am. J. Hum. Genet. 89(1)
Michael C. Wu, Seunggeun Lee, Tianxi Cai, Yun Li, Michael Boehnke, and Xihong Lin
Genome-wide association studies (GWAS) increasingly rely on rare genetic variants because common variants often explain only a small proportion of trait heritability. But standard methods for testing association with common genetic variants are usually underpowered for rare variants. This article describes a computationally efficient regression approach to test for association between variants (both common and rare) and phenotype, while accounting for population stratification. The authors describe analytic tools to guide the design of new sequence association studies of rare variants using their analysis method.
- Copyright © 2011 by the Genetics Society of America