Canadian Forest Service Publications
Decoupling of height growth and drought or pest resistance tradeoffs is revealed through multiple commongarden experiments of lodgepole pine. 2023. Liu, Y.; Erbilgin, N.; Cappa, E.P.; Chen, C.; Ratcliffe, B.; Wei, X.; Klutsch, J.G.; Ullah, A.; Azcona, J.S.; Thomas, B.R; El-Kassaby, Y.A. Evolution 77(3):893-906.
Issued by: Northern Forestry Centre
Catalog ID: 41035
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The environment could alter growth and resistance tradeoffs in plants by affecting the ratio of resource allocation to various competing traits. Yet, how and why functional tradeoffs change over time and space is poorly understood particularly in long-lived conifer species. By establishing four common-garden test sites for five lodgepole pine populations in western Canada, combined with genomic sequencing, we revealed the decoupling pattern and genetic underpinnings of tradeoffs between height growth, drought resistance based on δ13C and dendrochronology, and metrics of pest resistance based on pest suitability ratings. Height and δ13C correlation displayed a gradient change in magnitude and/or direction along warm-to-cold test sites. All cold test sites across populations showed a positive height and δ13C relationship. However, we did not observe such a clinal correlation pattern between height or δ13C and pest suitability. Further, we found that the study populations exhibiting functional tradeoffs or synergies to various degrees in test sites were driven by non-adaptive evolutionary processes rather than adaptive evolution or plasticity. Finally, we found positive genetic relationships between height and drought or pest resistance metrics and probed five loci showing potential genetic tradeoffs between northernmost and the other populations. Our findings have implications for deciphering the ecological, evolutionary, and genetic bases of the decoupling of functional tradeoffs due to environmental change
Plain Language Summary
The relationship between tree growth and resistance to pests and drought was investigated in lodgepole pine in Alberta. The chemical defenses pines produce against mountain pine beetle and the severity of western gall rust were used to estimate resistance. Stressful conditions caused by cold resulted in trees allocating relatively more resources to drought resistance at the expense of height growth. However, measures of mountain pine beetle and western gall rust resistance did not vary from cold to warm sites. Furthermore, there were positive genetic relationships among growth and drought and pest resistance. A gene was also identified that may impact these differing responses to stressful conditions. Information on what controls these growth and defense tradeoffs can inform tree breeding programs. The positive genetic relationships among important tree traits means foresters can breed for greater tree height and not have a decrease in potential resistance to pests. This research also has implications for understanding ecological, evolutionary, and genetic bases of how the environment and climate change impacts trees.