Phenotypic plasticity despite source-sink population dynamics in a long-lived perennial plant.
• Species that exhibit adaptive plasticity alter their phenotypes in response to environmental conditions, thereby maximizing fitness in heterogeneous landscapes. However, under demographic source-sink dynamics, selection should favor traits that enhance fitness in the source habitat at the expense of fitness in the marginal habitat. Consistent with source-sink dynamics, the perennial blueberry, Vaccinium elliottii (Ericaceae), shows substantially higher fitness and population sizes in dry upland forests than in flood-prone bottomland forests, and asymmetrical gene flow occurs from upland populations into bottomland populations. Here, we examined whether this species expresses plasticity to these distinct environments despite source-sink dynamics. • We assessed phenotypic responses to a complex environmental gradient in the field and to water stress in the glasshouse. • Contrary to expectations, V. elliottii exhibited a high degree of plasticity in foliar and root traits (specific leaf area, carbon isotope ratios, foliar nitrogen content, root : shoot ratio, root porosity and root architecture). • We propose that plasticity can be maintained in source-sink systems if it is favored within the source habitat and/or a phylogenetic artifact that is not costly. Additionally, plasticity could be advantageous if habitat-based differences in fitness result from incipient niche expansion. Our results illuminate the importance of evaluating phenotypic traits and fitness components across heterogeneous landscapes.
Anderson
Jill T
JT
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA. ja89@duke.edu
Sparks
Jed P
JP
Geber
Monica A
MA
D000220:Adaptation, Biological; D018533:Biomass; D017753:Ecosystem; D056084:Genetic Fitness; D010641:Phenotype; D018514:Plant Structures / Q000033:anatomy & histology / Q000502:physiology; D029796:Vaccinium / Q000033:anatomy & histology / Q000235:genetics* / Q000502:physiology