Role of abiotic factors and evolutionary history on the reproductive phenology traits of Himalayan Rhododendrons
The study was carried out from 2013 to 2015 across an altitude gradient of 3400–4230 m a.s.l. The study generated dated phylogenetic hypotheses to test for phylogenetic signal in reproductive phenology events, and its durations across ten Rhododendron species and also among groups of species distributed at every 100 m altitude.
Comparative phylogenetic methods were used to explore the relationship between phenology traits and abiotic variables such as daylength and temperature. The early phenology events such as budding, flowering, and initial fruiting, which occurred during the favorable month of the year, exhibited strong phylogenetic signal and were mainly associated with daylength and temperature. In contrast, the later events such as immature fruiting, mature fruiting, and fruit dehiscence, which occurred during the later months of the year, showed a weak phylogenetic signal and were mostly associated with daylength.
With the increase in altitude, the study found a decreasing trend of phylogenetic signal for the early phenology events and later events did not show a significant trend. The results suggest that only early events are constrained by evolutionary history; thus, the closely related species share the similar timing of the early phenology events. Also, the role of shared evolutionary history in phenological trait sensitivity to the abiotic factors reduces from early to the late phenology events. This approach can be extended to other representative plant families of the Himalayan region to better understand the response of reproductive traits to abiotic factors in deep evolutionary time.
For more information click on the link