Polyploids increase overall diversity despite higher turnover than diploids in the Brassicaceae.

Although polyploidy is widespread across the plant Tree of Life, its long-term evolutionary significance is still poorly understood. Here, we examine the effects of polyploidy in explaining the large-scale evolutionary patterns within angiosperms by focusing on a single family exhibiting extensive interspecific variation in chromosome numbers. We inferred ploidy from haploid chromosome numbers for 80% of species in the most comprehensive species-level chronogram for the Brassicaceae. After evaluating a total of 94 phylogenetic models of diversification, we found that ploidy influences diversification rates across the Brassicaceae. We also found that despite diversifying at a similar rate to diploids, polyploids have played a significant role in driving present-day differences in species richness among clades. Overall, in addition to highlighting the complexity in the evolutionary consequences of polyploidy, our results suggest that rare successful polyploids persist while significantly contributing to the long-term evolution of clades. Our findings further indicate that polyploidy has played a major role in driving the long-term evolution of the Brassicaceae and highlight the potential of polyploidy in shaping present-day diversity patterns across the plant Tree of Life.

Autopolyploid lineage shows climatic niche expansion but not divergence in Arabidopsis arenosa.

PREMISE OF THE STUDY: Successful establishment of neopolyploids, and therefore polyploid speciation, is thought to be contingent on environmental niche shifts from their progenitors. We explore this niche shift hypothesis in the obligate outcrosser Arabidopsis arenosa complex, which includes diploid and recently formed autotetraploid populations. METHODS: To characterize the climatic niches for both cytotypes in Arabidopsis arenosa, we first gathered climatic data from localities with known ploidy types. We then estimated the climatic niches for diploids and autotetraploids and calculated niche overlap. Using this niche overlap statistic, we tested for niche equivalency and similarity. We explored differences in niches by estimating and comparing niche optimum and breadth and then calculated indices of niche expansion and unfilling. KEY RESULTS: Climatic niche overlap between diploids and autotetraploids is substantial. Although the two niche models are not significantly divergent, they are not identical as they differ in both optimum and breadth along two environmental gradients. Autotetraploids fill nearly the entire niche space of diploids and have expanded into novel environments. CONCLUSIONS: We find climatic niche expansion but not divergence, together with a moderate change in the niche optimum, in the autotetraploid lineage of Arabidopsis arenosa. These results indicate that the climatic niche shift hypothesis alone cannot explain the coexistence of tetraploid and diploid cytotypes.

Genomic Signatures of Reinforcement.

Reinforcement is the process by which selection against hybridization increases reproductive isolation between taxa. Much research has focused on demonstrating the existence of reinforcement, yet relatively little is known about the genetic basis of reinforcement or the evolutionary conditions under which reinforcement can occur. Inspired by reinforcement's characteristic phenotypic pattern of reproductive trait divergence in sympatry but not in allopatry, we discuss whether reinforcement also leaves a distinct genomic pattern. First, we describe three patterns of genetic variation we expect as a consequence of reinforcement. Then, we discuss a set of alternative processes and complicating factors that may make the identification of reinforcement at the genomic level difficult. Finally, we consider how genomic analyses can be leveraged to inform if and to what extent reinforcement evolved in the face of gene flow between sympatric lineages and between allopatric and sympatric populations of the same lineage. Our major goals are to understand if genome scans for particular patterns of genetic variation could identify reinforcement, isolate the genetic basis of reinforcement, or infer the conditions under which reinforcement evolved.

[Hypolipidemic agents drug interactions: approach to establish and assess its clinical significance. Structured review]. / Interacciones medicamentosas de agentes hipolipemiantes: aproximación para establecer y valorar su relevancia clínica. Revisión estructurada.

OBJECTIVE: To carry out a structures review of drug interactions of hypolipidemic drugs and to assess their clinical relevance. METHOD: Structured review of drug interactions of hypolipidemic drugs in humans through PubMed/Medline of published articles, without language restrictions and with full text access until June 30th of 2012. The following Mesh terms were used: Drug Interactions, Lipid Regulating Agents, Herb-Drug Interactions, Food-Drug Interactions y Hypolipidemic Agents (Pharmacological Action). The information was completed with those articles considered to be relevant. Finally, a method was used to assess the clinical relevance of the interaction, based on the likelihood of occurrence and the severity of the effect of the interaction. RESULTS: 849 publications were gathered, of which 243 references were selected, among which 189 interactions were identified. Thirty-three of them were considered of very high risk (level 1) and 42 of high risk (level 2), basically associated to increased risk for rhabdomyolisis. Enzymatic inhibition of CYP450 was the most common mechanism for these interactions. CONCLUSIONS: Of the interactions identified in patients on hypolipidemic drugs, 60.3% (128/189) are clinically relevant (very high or high risk), mainly associated to the occurrence of rhabdomyolisis. Most of these interactions are attributed to simultaneous use of CYP3A4 inhibitors. Therefore, statins metabolized through CYP3A4 (simvastatin, lovastatin and atorvastatin) are the ones with the highest number of clinically relevant interactions.

Objetivo: Realizar una revisión estructurada sobre interacciones medicamentosas de los hipolipemiantes y valorar su relevancia clínica. Método: Revisión estructurada de interacciones medicamentosas con hipolipemiantes en humanos, en PubMed/Medline de artículos publicados sin restricción de idioma, con acceso a texto completo hasta junio 30 de 2012. La búsqueda se realizó con los siguientes terminos Mesh: Drug Interactions, Lipid Regulating Agents, Herb-Drug Interactions, Food-Drug Interactions y Hypolipidemic Agents (Pharmacological Action). La información se complementó con artículos considerados importantes. Por último, se utilizó un método para evaluar la relevancia clínica de la interacción, basado en la probabilidad de ocurrencia y en la gravedad del efecto de la interacción. Resultados: Se obtuvieron 849 publicaciones, de las cuales se seleccionaron 243 referencias, en las los que se identificaron 189 interacciones. De ellas 33 fueron valoradas como de riesgo muy alto (nivel 1) y 42 de riesgo alto (nivel 2), asociadas fundamentalmente al aumento del riesgo de rabdomiólisis. La inhibición enzimática de la CYP450 fue el mecanismo más común de las interacciones. Conclusiones. En los pacientes en tratamiento con hipolipemiantes, de las interacciones identificadas 60,3% (128/189) son clínicamente relevantes (riesgo muy alto o alto), asociadas principalmente a la aparición de rabdomiólisis. La mayoría de dichas interacciones son atribuidas al uso simultáneo de reconocidos inhibidores de la CYP3A4. Por ello, las estatinas metabolizadas por la CYP3A4 (simvastatina, lovastatina y atorvastatina) son las que más interacciones de relevancia clínica presentan.