Different Blossoming Schedules Have Kept Rhododendron Species from Driving Each Other Extinct
Published:07 Nov.2022    Source:Field Museum

The flower-covered meadows of China's Hengduan mountains were an evolutionary mystery -- there are dozens of species of closely-relatedrhododendrons that all live in harmony. To figure out why, scientists spent a summer carefully documenting the flowering patterns of 34 Rhododendron species. 

Rhododendrons are flowering shrubs. The Hengduan Mountains, adjacent to the Qinghai-Tibet Plateau, are what biologists call a biodiversity hotspot: an ecologically fragile place with unusually high numbers of different species. The Rhododendron diversity in this area is caused in part by speciation, which is when new species diverge from a common ancestor. That means that the closely-related rhododendrons in the Hengduan Mountains should be even likelier to compete with each other for resources.
When plants are in competition with each other, there are lots of ways they can adapt so that they can co-exist. They can become very different in terms of their preferences for soil, light, and moisture, very basic physiological functional traits. They can also evolve differences to reduce this potential for cross pollination or competing for pollinators. That would be manifested through differences in flower shape, size, or color, or could be manifested in when they make their flowers available for pollinators. By partitioning that timeline, they can reduce their chances of wasting their pollen and the resources that go into reproduction.