Climate change exacerbates abiotic stressors like drought and reshapes the timing and compatibility of plant–pollinator interactions. Flower color polymorphisms across environmental clines can offer insights into plant responses to such changes. Anemone coronaria, a widespread geophyte in Israel, exhibits red-only populations in arid regions and both red-only and color-polymorphic populations in mesic Mediterranean habitats.
To explore drought resilience across flower-color morphs, we grew corms from arid and Mediterranean origins under high and low irrigation in a common garden. The red morph showed greater relative corm growth under low irrigation. It also flowered later than non-red, regardless of irrigation treatment. Corm size was tightly linked to flowering time: larger corms flowered earlier and for a longer duration, regardless of color. Red anemones from arid origins, which had tiny corms, were therefore the last to flower.
To connect these patterns to pollination interactions, we monitored insect visits to experimental flower arrays in three field sites over two flowering seasons. Bees and flies visited non-red morphs in early season at Mediterranean sites, while glaphyrid beetles preferred red morphs later in the season at an arid site.
Our findings suggest that under drought, red morphs gain a physiological edge and postpone flowering – potentially enhancing encounters with their late-season beetle pollinators. Low rainfall may also slow corm development in non-red morphs, delaying their earlier flowering and shortening their overlap with key early-season pollinators. Such phenological shifts could weaken pollination services in color-polymorphic populations and favor red-only populations under climate stress.
