Romiguier et al. sequenced the transcriptomes of 2–10 individuals from each of 76 non-model animal species to quantify the population genetic diversity, followed by analyses of ecological, biological or geographical features that correlate with the level of diversity. They found that strong parental investment in raising offspring was the best predictor of low genetic diversity. Populations of these low-diversity species, including numerous invertebrates, might be the least able to recover following environmental perturbation.