Comment on "precipitation drives global variation in natural selectio"

Abstract

Siepielski et al. (Reports,3March 2017, p. 959) claimthat "precipitation drives global variation in natural selection." This conclusion is based on a meta-analysis of the relationship between climate variables and natural selection measured in wild populations of invertebrates, plants, and vertebrates.Three aspects of this analysis cause concern: (i) lack of within-year climate variables, (ii) low and variable estimates of covariance relationships across taxa, and (iii) a lack of mechanistic explanations for the patterns observed; association is not causation.