Asymmetric introgression and thermal advantage jointly drive climate-mediated lineage turnover in a mixed-ploidy reed.

Asymmetric introgression and thermal tolerance give the octoploid FEAU lineage a climate-driven advantage, leading to potential replacement of cold-adapted lineages in China.

• Why it matters: Understanding intraspecific genetic variation is crucial for accurate climate impact predictions, yet it is often overlooked in species distribution models, risking incomplete forecasts of lineage shifts.
• What they did: The study combined population genomics of 495 individuals, common-garden experiments at four sites, and distribution modeling of 837 records across three lineages of Phragmites australis, revealing differences in heat tolerance and gene flow patterns.
• The result: Findings show FEAU's thermal advantage and asymmetric gene flow promote its expansion under climate change, emphasizing the need to incorporate genetic and evolutionary factors into ecological forecasts.