Tim is a postdoc at the University of British Columbia, Canada. He is an ecophysiologist interested in how plants respond to differences in climate. Here, he shares his recent research on how phylogeny and climate predict little variation in plant heat tolerance responses.
Author Timothy Perez, some bromeliads, aroids, and a rainbow eucalyptus tree at Fairchild Tropical Botanic Garden
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Institute. University of Miami; University of British Columbia
Academic life stage. Postdoc
Major research themes. Plant physiological ecology, thermal ecology, climate change, evolution conservation biology
Recent paper in JBI. Perez, TM, Feeley, KJ. Weak phylogenetic and climatic signals in plant heat tolerance. J. Biogeogr. 2021; 48: 91– 100. https://doi.org/10.1111/jbi.13984
Motivation behind this paper. The motivation behind our paper was trying to understand if physiological tolerances influence patterns in species’ climatic distributions. More specifically, we wanted to know if hot climates act as environmental filters on community assembly. Physiological tolerances, like the heat tolerances of photosystem II (PSII) photochemistry, are thought to exert strong constraints on carbon assimilation, and by extension plant growth, survival and reproduction. Therefore, heat tolerances of PSII (hereafter heat tolerance) may reveal information about the kinds of species that can exist in hot climates. This information could be useful for predicting which species are most vulnerable to climate change and understanding how ecosystem processes may change in future climates.
Key methodologies. In our study, we took advantage of museum collections – specifically, the living plant collections of Fairchild Tropical Botanic Garden. Botanic gardens are great places to conduct ecophysiological research because plants with different ecologies and evolutionary histories are all growing together in a common garden-like environment. In other words, there is a lot of plant diversity, which can be harnessed to investigate different aspects of plant physiology. In our project, this common garden environment allowed us to sample many different species and understand how phylogenetic relatedness may influence variation in plant heat tolerance.
Sunrise over the botanical garden
Any challenges you and your co-authors faced along the way? Since I was working in a botanical garden, my study species were very easy to locate because the location of each plant (within the garden) that I wanted to sample had been mapped by garden curators. This is in contrast to most tropical fieldwork that requires hours of searching for your species of interest. This study was not my first campaign sampling plant traits or heat tolerances, which is another reason why data collection went fairly smoothly for this project. Luckily, there were no hurricanes during the sampling campaign, which have caused interruptions in my previous studies. I’m happy (and lucky!) that the project went as smoothly as it did.
Major results. Two important findings of our study were that species’ climatic distributions and heat tolerances are poorly coordinated, and that phylogeny explains little of the variation in plant heat tolerance. These results mean that hot climates are unlikely to influence patterns of community assembly based on heat tolerance alone, and that closely related species are not expected to exhibit similar tolerances. However, our results do point towards the importance of leaf thermoregulatory traits as a potential way forward for understanding variation in heat tolerance and how it may influence plant ecology. Thermoregulatory traits can cause leaves to experience different temperatures than ambient air temperatures. Therefore, leaf temperatures may be important for explaining variation in thermal tolerance and species’ distributions (see: https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2435.13658).
Species in the study were also sampled from the University of Miami’s Gifford Arboretum
Next steps in this research. Plant heat tolerances have been studied extensively, but we lack a coherent understanding of how variation in heat tolerance is linked to abiotic conditions. It is also unclear how heat tolerance integrates with carbon assimilation or aspects of plant productivity (see: https://onlinelibrary.wiley.com/doi/10.1111/pce.13990). I think these topics are important areas of future plant heat tolerance research.
If you could study any organisms on Earth, what would it be? I study plants because I think they are the coolest organisms on Earth! Plants dominate Earth’s biosphere, provide humans with essential ecosystem services, and are vital for mitigating climate change. There are endless practical reasons for why I study plants, including the fact that they are found just about everywhere, and the opportunities to study them are endless. However, I also just find plants and all of their strange forms and functions marvellously beautiful.