Research Summary

My work uses phylogenetic trees to address fundamental questions on the origin and distribution of biodiversity. In particular, I am interested in why some regions and some lineages contain more species than others. To date, approaches for studying these two patterns have been largely separate. Numerous studies have sought explanations for taxonomic imbalance, concentrating on the role of key biological traits, such as pollination syndrome or growth form, but in flowering plants (as in other groups) such traits apparently explain relatively little of the variation in species numbers. At the same time, ecological studies have explored the effects of environment on floristic richness within regions, but have not traditionally addressed evolutionary explanations. Phylogenetics offers a powerful means to combine both approaches. A better understanding of the processes shaping biodiversity patterns will also be critical if we wish to reduce current rates of biodiversity loss.

Plant Responses to Climate Change

Study Shows Experiments Underestimate Plant Responses to Climate Change
Experiments may dramatically underestimate how plants will respond to climate change in the future. That’s the conclusion of our analysis of 50 plant studies on four continents, published in the journal Nature, which found that shifts in the timing of flowering and leafing in plants due to global warming appear to be much greater than estimated by warming experiments.

Our study suggests that predicted ecosystem changes—including continuing advances in the start of spring across much of the globe—may be far greater than current estimates based on data from experiments. Up to now, it’s been assumed that experimental systems will respond the same as natural systems respond—but they don’t. Experiments predict that every degree rise Celsius would advance plants’ flowering and leafing from half a day to 1.6 days. But in looking at actual observations in nature, we found advances four times faster for leafing—and over eight times faster for flowering. These records consistently showed that phenological events are advancing, on average, about 5 to 6 days per degree Celsius.