Seed dormancy in space and time: global distribution, paleo- and present climatic drivers and evolutionary adaptations ($) (New Phytol.)

Seed dormancy is widely recognized as a key mechanism to ensure that germination takes place under the most suitable conditions. Such is its importance that multiple studies have described the morphological, physiological, and genetic mechanisms behind it, yet its global distribution and the past and current environmental drivers behind it have seldom been addressed. Based on a database of more than 12,400 species, Zhang, Liu, Sun, and colleagues found that the lowest proportion of species with dormant seeds is found in the Arctic and the tropical rainforests near the Equator, whereas the middle-latitudes host the highest proportion, and areas with seasonal climates and wide diurnal temperature ranges have a high proportion of species with dormant seeds. The authors also found that this proportion has gradually decreased since the Cenozoic –the era between 65 million years ago and the present– potentially due to increasing temperatures that favor the absence of dormancy. However, all these global patterns varied between herbaceous and woody species, implying that the adaptive value of seed dormancy depends on plant growth form. This research provides fascinating insights into the biogeography and evolution of seed dormancy. (Summary by Carlos A. Ordóñez-Parra @caordonezparra) New Phytol. 10.1111/nph.18099