Phenotypic selection on leaf ecophysiological traits in Helianthus.
Habitats that differ in soil resource availability are expected to differ for selection on resource-related plant traits. Here, we examined spatial and temporal variation in phenotypic selection on leaf ecophysiological traits for 10 Helianthus populations, including two species of hybrid origin, Helianthus anomalus and Helianthus deserticola, and artificial hybrids of their ancestral parents. Leaf traits assessed were leaf size, succulence, nitrogen (N) concentration and water-use efficiency (WUE). Biomass and leaf traits of artificial hybrids indicate that the actively moving dune habitat of H. anomalus was more growth limiting, with lower N availability but higher relative water availability than the stabilized dune habitat of H. deserticola. Habitats differed for direct selection on leaf N and WUE, but not size or succulence, for the artificial hybrids. However, within the H. anomalus habitat, direct selection on WUE also differed among populations. Across years, direct selection on leaf traits did not differ. Leaf N was the only trait for which direct selection differed between habitats but not within the H. anomalus habitat, suggesting that nutrient limitation is an important selective force driving adaptation of H. anomalus to the active dune habitat.
Donovan
L A
LA
Department of Plant Biology, University of Georgia, Athens GA 30606, USA.
Ludwig
F
F
Department of Plant Biology, University of Georgia, Athens GA 30606, USA.
Rosenthal
D M
DM
Department of Plant Biology, University of Georgia, Athens GA 30606, USA.
Rieseberg
L H
LH
Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
Dudley
S A
SA
Department of Biology, McMaster University, Hamilton, Ontario, L8S 4K1, Canada.
D018533:Biomass; D017753:Ecosystem; D006368:Helianthus / Q000235:genetics* / Q000502:physiology*; D006824:Hybridization, Genetic; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics* / Q000502:physiology*; D011157:Population Dynamics; D019655:Quantitative Trait, Heritable; D012641:Selection, Genetic; D013997:Time Factors