Abstract Detail

Ecophysiology

Navarro, Jocelyn [1], Powers, John [2], Paul, Ayaka [3], Campbell, Diane [4].

Phenotypic plasticity and selection on leaf traits in response to snowmelt timing and summer precipitation.

In addition to being shaped over generations by natural selection, vegetative traits of plants can respond directly to changes in the environment, such as those occurring under climate change. That phenotypic plasticity often involves tradeoffs between growth and water conservation and could be adaptive, maladaptive, or neutral. Adaptive plasticity aids plant population persistence during rapid environmental shifts by favoring individuals that respond morphologically or physiologically to the new conditions in a way that maintains fitness. In cold ecosystems, anthropogenic climate change is hastening snowmelt and disrupting precipitation, but plant responses through vegetative trait plasticity, and the resulting fitness consequences, are poorly understood. In an experiment in the Colorado Rocky Mountains, we manipulated the timing of spring snowmelt and amount of summer precipitation in factorial combination and examined responses of specific leaf area (SLA), trichome density, leaf water content (LWC), photosynthetic rate, stomatal conductance, and intrinsic water-use efficiency (iWUE) in the subalpine herb Ipomopsis aggregata. The experiment was repeated in three years differing in natural timing of snowmelt. To examine natural selection, we used survival, relative growth rate, and flowering as fitness indices. A 50% reduction in summer precipitation reduced stomatal conductance and increased iWUE, and doubled precipitation increased LWC. Combining natural and experimental variation, earlier snowmelt reduced soil moisture, photosynthetic rate and stomatal conductance, and increased trichome density and iWUE. Precipitation reduction reversed the mortality selection favoring high stomatal conductance under normal and doubled precipitation, and higher LWC improved growth. We conclude that earlier snowmelt is a strong signal of climate change and can change expression of leaf morphology and gas exchange traits, just as reduced precipitation can. Two water-saving traits, stomatal conductance and SLA, showed adaptive plasticity under some conditions. In the face of more frequent extreme drought, selection for plants that shift to trait values that improve fitness could aid population persistence, depending on the levels of genetic variation in plasticity and in the traits.

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New Phytologist article

1 - University Of Arizona, 1041 E Lowell St, Biosciences West Room 310, Tucson, AZ, 85721, United States
2 - University of California, Irvine, Ecology and Evolutionary Biology, 321 Steinhaus Hall, Irvine, CA, 92697, USA
3 - Colorado State University, Biology, 1878 Campus Delivery, Fort Collins, CO, 80523, USA
4 - University Of California, Irvine, Department Of Ecology And Evolutionary Biology, 321 Steinhaus Hall, Irvine, CA, 92697, United States

Keywords:
adaptive plasticity
Ipomopsis aggregata
vegetative traits
Phenotypic plasticity
precipitation
snowmelt
stomatal conductance
water use efficiency.

Presentation Type: Oral Paper
Number: EPH2008
Abstract ID:499
Candidate for Awards:None