Abstract Detail

Ecology

Zettlemoyer, Meredith [1], Conner, Rebecca [2], Seaver, Micaela [3], Waddle, Ellen [3], DeMarche, Megan [1].

Advancing phenology is adaptive but insufficient to maintain reproductive success under warmer climates.

Assessing whether plasticity in response to climate change is in an adaptive direction requires investigating the relationships among phenotype, fitness, and environmental drivers of selection. For plasticity to be adaptive there must be natural selection on mean phenotypes, and selection must favor trait change in the same direction as plasticity. Despite widely-documented advancements in phenology, we are rarely able to distinguish between adaptive and maladaptive plastic responses. Additionally, we lack empirical estimates of how selective landscapes shift with continuous climate drivers in wild populations. Finally, few studies investigate how individuals within a population may differ in plasticity despite potential consequences for fitness. Here, we leverage an unusual long-term dataset with repeated, individual measurements of flowering phenology and reproduction in a long-lived alpine plant, Silene acaulis (Caryophyllaceae). We conduct a rare quantitative assessment of plasticity and natural selection on phenology via continuous climate drivers (growing degree days and snowmelt timing), allowing us to test whether plasticity is adaptive. We find that nonlinear directional selection favors earlier flowering during colder climate conditions. Phenological plasticity enables populations to track optimal colder flowering conditions by flowering earlier during warmer or earlier melting years, suggesting that plasticity is adaptive. However, reproduction still declines with warming, even with early flowering, suggesting that even adaptive phenological plasticity is insufficient to maintain fitness in warming climates. Individuals differed in the magnitude of their phenological plasticity, resulting in greater variation in flowering time under warmer conditions. Our findings demonstrate a need to consider the limits of adaptive phenological plasticity in maintaining fitness under climate change.

1 - University of Georgia, Department of Plant Biology
2 - North Park University, Department of Biology
3 - University of Colorado Boulder, Department of Ecology and Evolutionary Biology

Keywords:
adaptive plasticity
climate change
fitness landscape
individual variability
phenology
selection
growing degree days
snowmelt
flowering
individual x environment interactions
fitness
phenological shifts
continuous environmental drivers.

Presentation Type: Oral Paper
Number: EC05001
Abstract ID:124
Candidate for Awards:None