Phylogenetic conservatism in flowering phenology in eastern Tibet Plateau
Flowering phenology is affected by many factors but most important are: local climatic, biotic interactions and phylogenetic conservatism. Phylogenetic conservatism implies that more closely related species tend to flower at similar times. Though this hypothesis has been supported in previous studies, little work has been done with using fully resolved phylogenies and examining community wide flowering using long-term data. Here we collected phenology data (flowering peak day: FPD, first flower budding: FFB, first flowering day: FFD, first fruiting day: FFR) from alpine meadow and swap meadow for five years in 50 permanent plots. We obtained well-resolved phylogenetic trees through the plastid region sequences (rbcL, matK) and incompletely resolved phylogenetic tree by using Phylomatic software. We used four different methods to explore phylogenetic constraint on flowering phenology, and were able to test how microclimate and community context influenced flowering time.
Perhaps, it is not surprise that our results suggested a phylogenetic conservatism in phenological events consistently across the communities and methods but they were still quite exciting. We found some interesting phenomenon in our results: incompletely resolved phylogenetic trees will inflate estimates of phylogenetic conservatism with Blomberg’s K which may be the most popular calculation method to evaluate phylogenetic conservatism. Our results also revealed that phylogenetic conservatism in FPD tends to be weaker with the increase of spatial scale. That means when we try to test phylogenetic hypothesis in plant phenology, we should consider the spatial scales for the influence of external clues. In summary, we found strong evidence supporting the importance of phylogenetic conservatism in flowering phenology.