A study of how different rainfall levels affect the fitness of different Arabidopsis thaliana lines suggests that climate change is driving natural selection in the model plant's genome, according to a report in Nature this week. The researchers used the extensive genomic data available on the plant to examine how the amount of rainfall affected the fitness of 517 natural Arabidopsis lines grown in Spain and Germany in order to directly infer selection along the genome. They find that natural selection was particularly strong in the hot and dry location in Spain, where 63 percent of lines were killed and where natural selection substantially changed the frequency of approximately 5 percent of all genome-wide variants. Field-validated predictions across the species range, meanwhile, indicated that Mediterranean and western Siberian Arabidopsis populations — which live at the environmental limits of the species — currently experience the strongest climate-driven selection. "Our experiments provide a proof-of-concept of the use of genome-wide environment selection models for evolution-aware predictions of climate-change-associated risks for biodiversity," the study's authors write.
Individuals with low or moderate genetic predisposition for dementia may reduce their risk for the condition with health and lifestyle changes, according to a study appearing in Nature Medicine this week. Scientists analyzed long-term data on both genetic and modifiable risk factors from 6,352 individuals aged 55 years and older in the population-based Rotterdam Study. They find that individuals with a low or intermediate dementia risk who had a favorable lifestyle score — based on factors such as regular exercise and limited alcohol consumption — were less likely to develop dementia than those with a similar genetic risk profile but unfavorable lifestyle score. Notably, lifestyle score did not appear to influence the development of dementia in those at high genetic risk. "These results may inform clinical-trial design because dementia prevention trials increasingly recruit individuals genetically predisposed to dementia," the researchers note.