Why this self-pollinating plant's flowers shrink at the edges of its range
Sartori K, Mestre CF, Hossain MJ, Estarague A, Gaignon E, Moulin P, Lasky JR, Vile D, Vasseur F, Violle C, Sicard A.
Climate Adaptation
If you've ever noticed that the same wildflower species looks different from one hillside to the next, this shows environment alone, not just bees and butterflies, can rewrite a plant's flower size over generations.
Arabidopsis thaliana pollinates itself, so scientists expected it to eventually settle on one 'best' flower size since it doesn't need to impress any pollinators. Instead, they found flower size varies a lot across its range, and the pattern tracks climate: in tough, marginal habitats only small flowers survive, but in comfortable habitats both small and large flowers stick around. It's a reminder that flowers aren't shaped by pollinators alone; soil, weather, and stress leave their own fingerprints on plant form.
Key Findings
Flower size in Arabidopsis thaliana is controlled by many genes (polygenic), with different alleles independently pushing petal size up or down, some showing signs of positive selection.
Purifying selection favors small flowers specifically at the species' climatic range margins, where resources are more limited.
In more favorable, less stressful habitats, selection relaxes, letting both small- and large-flowered variants coexist and persist.
chevron_right Technical Summary
Scientists studying Arabidopsis thaliana, a small self-pollinating plant, found that flower size across its range isn't shaped by pollinators but by local climate: harsh, marginal habitats push evolution toward smaller flowers, while milder regions allow both big and small flowers to persist.
Abstract Preview
Original paper
Local Trade-Offs Shape Flower Size Evolution Across Arabidopsis thaliana Distribution.
The remarkable variation in floral form and size is thought to have driven the evolutionary radiation of angiosperms and has traditionally been attributed to pollinator-mediated selection on floral...
open_in_new Read full abstractAbstract copyright held by the original publisher.
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