Reproductive isolation between wild and domesticated chaya (Cnidoscolus aconitifolius) in sympatry

• Reproductive isolation is a necessary condition for plant domestication in their domestication centre where crops co‐occur with their wild progenitors. However, the identification of reproductive barriers and their relative contribution to reproductive isolation have been overlooked in plants under domestication.
• We assessed pre‐ and post‐pollination reproductive barriers and their relative contribution to reproductive isolation between wild and domesticated chaya (Cnidoscolus aconitifolius) in its domestication centre.
• We found that wild and domesticated chaya both exhibit a high degree of reproductive isolation. However, the reproductive isolation barriers exhibited some asymmetry: while pre‐pollination barriers (differential pollen production and pollinator specificity) were only detected in wild plants, post‐pollination barriers (pollen–pistil incompatibility and/or failure to set fruit) were observed in both wild and domesticated plants.
• We conclude that complete reproductive isolation has evolved in sympatry in co‐occurring domesticated and wild chaya.