Our geographical genomic survey of gene expression variation in southern Morocco has highlighted two parallel and for the most part non-overlapping insights. On the one hand, it is evident that as much as half of the transcriptome is influenced by the environment in a highly coordinated manner such that where a person lives explains up to a quarter of the variation for a substantial fraction of the transcripts. The environmental influences are likely a combination of biotic and abiotic factors, as well as cultural and behavioral ones, while genetic differences between the two North African ethnicities are relatively minor. On the other hand, the genome is littered with strong genetic associations, mainly in cis, that explain between 15 and 60 percent of the variance of 5% of the transcripts. Impressive as these associations are, particularly since they are discovered in a sample of just under 200 individuals, they have essentially no bearing on the vast majority of the transcriptional variation, and are not informative of the genetic basis of the environmental response.
