California State University Dominguez Hills, United States
Abstract: Climate change can influence evolutionary and ecological processes in plants by causing a mismatch between the activity of plants and pollinators, leading to decreased pollination and increased inbreeding. However, the breeding system of the plant can minimize inbreeding if a plant is self-incompatible. Our previous research found variability in the breeding systems across Oenothera (Onagraceae), which grow in extreme environments already heavily influenced by climactic variation. The pale evening primrose, Oenothera pallida ssp. pallida is commonly found on exposed sand dunes from Washington to Utah and is primarily pollinated by hawkmoths. This is important because as the climate changes, the pollinators will become less reliable, increasing mating with close relatives. Therefore, it is vital to understand the diversity of breeding systems as it impacts the plant's distribution and fitness. We obtained seeds from 14 populations of Oenothera pallida ssp. pallida from across its home range. After germination, we assessed the breeding system using hand pollination.
We found variation in the breeding system across the populations, although some populations had very low flower production. We used a mixed-effect linear regression to determine the impact of pollination treatment, maternal and paternal plants, and the population on fruit production. Overall, our outcrossed flowers, which received pollen from another plant, had more successful fruit production than self-crossed flowers (P < 0.001). Additionally, we found that the maternal plant had a significant effect on fruit production (P < 0.001). Our results suggest that outcross plants have a higher success rate of fruit production, promoting genetic diversity and strengthening their ability to survive and resist changes in climate. However, we had success in multiple populations with self-crossed flowers producing fruits, indicating that the self-incompatibility system isn’t infallible. In conclusion, Oenothera pallida ssp. pallida comes from an extreme environment that makes it a valuable species in examining breeding systems and climate change.
