In natural ecosystems, the ability to disperse seeds and maintain dormancy are key survival and population maintenance strategies for plants. However, the interaction between these two mechanisms across different climatic regions, which determines maximum dispersal distance and species range size, remains poorly understood.

On April 19, a study published in Global Ecology and Biogeography by researchers from the Xishuangbanna Tropical Botanical Garden of the Chinese Academy of Sciences and their collaborators reveals that the relationship between seed dormancy and dispersal syndromes shapes seed dispersal distance and species range size in climate-specific ways.

To investigate these interactions, the researchers compiled data from 631 seed plant species across 118 families worldwide. They systematically tested how the trade-off between maximum seed dispersal distance and seed dormancy varies between animal-dispersed and non-animal-dispersed plants. They also examined the modifying role of climate and how these strategies affect range sizes in tropical and temperate regions.

According to the researchers, among seeds that rely on non-living forces such as wind or water (abiotic dispersal), non-dormant species achieve significantly greater dispersal distances than dormant species, reflecting a trade-off between dispersal capacity and persistence traits (dormancy). In contrast, animal-dispersed seeds travel equally long distances regardless of whether they are dormant or not.

Crucially, the influence of dormancy and dispersal on a species' final geographic range size was not the same everywhere. In the tropics, animal dispersal significantly promotes larger range sizes, while the effect of seed dormancy is comparatively weak. In temperate regions, neither dispersal syndrome nor dormancy alone has a strong direct effect on range size. However, maximum dispersal distance is positively correlated with range size, highlighting the importance of achieving long-distance dispersal in temperate floras.

This study provides a new framework for predicting plant migration in the context of climate change. As species attempt to track shifting climate envelopes, the ability to disperse over long distances and to persist through unfavorable years will be critical.

"You cannot look at dispersal or dormancy in isolation," said YANG Jie of XTBG. "To predict which plants will thrive and which will struggle, we need to know three things: Is the seed dormant? Is it dispersed by animals or the wind? And where in the world is it growing? All three factors jointly matter."