Dhaka September 16, 2014. In an article entitled, ‘Genetic erosion in maize’s center of origin’ published in September 2, 2014, issue of PNAS (doi:10.1073/pnas.1407033111), the lead author George A. Dyer with three other associates from five different research institutes have reported that the diversity of maize varieties grown on farms across Mexico has declined in recent years and this phenomenon may threaten crop yields in the face of the climate change. The practice of saving seed on farms and passing the seed to succeeding generations exposes crops to natural selection and allows them to adapt and remain productive with a varietal diversity improving a crop’s chances of successful adaptation. They measured the diversity of maize varieties grown in 1,725 farms across Mexico between 2002 and 2007 to assess the degree of farm-based conservation of crop varieties. According to direct measurements, maize diversity decreased from 1.43 to 1.22 varieties in five years. In contrast, indirect estimates from case studies showed an increase in varietal diversity, indicating that the indirect method may overestimate maize diversity and conceal loss of varieties. Furthermore, direct measurements of varietal loss yielded similar results across regions and altitudes, even among the farmers who grow maize continuously, suggesting that the phenomenon of decreasing diversity is widespread and enduring. According to the authors, decreasing diversity of actively grown maize varieties may limit crop adaptation to climate change, potentially resulting in reduced yields, farm abandonment, and further loss of crop diversity. Failure to conserve crop diversity in the face of climate change may also jeopardize food security efforts around the world. [summarized by Samsad Razzaque – a DU graduate student in pbtlabdu.net.