Local Adaptation Drives Leaf Thermoregulation in Tropical Rainforest Trees
Middleby, Kali B., Jordan, Rebecca, Cheesman, Alexander W., Rossetto, Maurizio, Breed, Martin F., Crayn, Darren M., and Cernusak, Lucas A. (2025) Local Adaptation Drives Leaf Thermoregulation in Tropical Rainforest Trees. Global Change Biology, 31 (9). e70461.
|
PDF (Published Version)
- Published Version
Available under License Creative Commons Attribution Non-commercial. Download (5MB) | Preview |
Abstract
Tropical forests play a critical role in biodiversity, carbon sequestration, and climate regulation, but are increasingly affected by heatwaves and droughts. Vulnerability to warming may vary within and between species because of phenotypic divergence. Leaf trait variation can affect leaf operating temperatures—a phenomenon termed ‘limited homeothermy’ when it helps avoid heat damage in warmer conditions. However, evidence for this capacity and the relative roles of acclimation or adaptation remain limited. We measured photosynthetic heat tolerance and leaf thermal traits of three co-occurring rainforest tree species across a thermal gradient in the Australian Wet Tropics. Using a leaf energy balance model parameterised with field-measured traits, we predicted variation in leaf-to-air temperature differences (∆Ttrait) and resulting thermal safety margins. We combined this with individual-based genome-wide data to detect signals of adaptive divergence and validated findings in a glasshouse trial with provenances grown under contrasting temperature and humidity conditions. Intraspecific trait variation reduced ∆Ttrait and increased heat tolerance in warmer sites for Darlingia darlingiana and Elaeocarpus grandis, but not Cardwellia sublimis. As a result, thermal safety margins declined less steeply with increasing growth temperature in species capable of increased heat tolerance and avoidance, indicating these strategies can effectively buffer warming. All species showed genomic signals of selection, with associations to temperature and moisture variables. In E. grandis, glasshouse results confirmed a negative cline in ∆Ttrait with temperature of origin. Although contrasting growth temperature and humidity lead to acclimation of individual traits, their coordination maintained ∆Ttrait across the conditions imposed. Our findings provide evidence of limited homeothermy and suggest climate gradients have selected for trait combinations that reduce leaf temperatures at warmer sites in some but not all species. Given the rapid pace of climate change, those species with limited capacity to adjust their thermal safety margins through acclimation or adaptation may be at greater risk of local extinction.
| Item ID: | 89088 |
|---|---|
| Item Type: | Article (Research - C1) |
| ISSN: | 1354-1013 |
| Keywords: | functional traits, intraspecific trait variation, leaf energy balance,leaf temperature, leaf thermoregulation, limited homeothermy, local adaptation, population genomics, thermal tolerance, tropical rainforest |
| Related URLs: | |
| Copyright Information: | © 2025 The Author(s). Global Change Biology published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in anymedium, provided the original work is properly cited and is not used for commercial purposes. |
| Funders: | Australian Research Council (ARC) |
| Projects and Grants: | ARC LP190100484, ARC DP210103186 |
| Date Deposited: | 07 Oct 2025 22:13 |
| More Statistics |
Actions (Repository Staff Only)
 |
Item Control Page |