title: Adaptive differentiation of traits related to resource use in a desert annual along a resource gradient.
abstract: • Plant resource-use traits are generally hypothesized to be adaptively differentiated for populations distributed along resource gradients. Although nutrient limitations are expected to select for resource-conservative strategies, water limitations may select for either resource-conservative or -acquisitive strategies. We test whether population differentiation reflects local adaptation for traits associated with resource-use strategies in a desert annual (Helianthus anomalus) distributed along a gradient of positively covarying water and nutrient availability. • We compared quantitative trait variation (Q(ST)) with neutral genetic differentiation (F(ST)), in a common garden glasshouse study, for leaf economics spectrum (LES) and related traits: photosynthesis (A(mass), A(area)), leaf nitrogen (N(mass), N(area)), leaf lifetime (LL), leaf mass per area (LMA), leaf water content (LWC), water-use efficiency (WUE, estimated as δ(13)C) and days to first flower (DFF). • Q(ST)-F(ST) differences support adaptive differentiation for Amass , N(mass), N(area), LWC and DFF. The trait combinations associated with drier and lower fertility sites represent correlated trait evolution consistent with the more resource-acquisitive end of the LES. There was no evidence for adaptive differentiation for A(area), LMA and WUE. • These results demonstrate that hot dry environments can selectively favor correlated evolution of traits contributing to a resource-acquisitive and earlier reproduction 'escape' strategy, despite lower fertility.
authors: Department of Plant Biology, University of Georgia, 2502 Miller Plant Sciences, Athens, GA, 30602, USA.
authors: Larry C
authors: LC
authors: Brouillette
authors: Department of Plant Biology, University of Georgia, 2502 Miller Plant Sciences, Athens, GA, 30602, USA.
authors: Chase M
authors: CM
authors: Mason
authors: Department of Plant Biology, University of Georgia, 2502 Miller Plant Sciences, Athens, GA, 30602, USA.
authors: Rebecca Y
authors: RY
authors: Shirk
authors: Department of Plant Biology, University of Georgia, 2502 Miller Plant Sciences, Athens, GA, 30602, USA.
authors: Lisa A
authors: LA
authors: Donovan
mesh_terms: D003889:Desert Climate; D005819:Genetic Markers; D014644:Genetic Variation; D005843:Geography; D006368:Helianthus / Q000235:genetics* / Q000254:growth & development; D018895:Microsatellite Repeats / Q000235:genetics; D019655:Quantitative Trait, Heritable
chemical_list: D005819:Genetic Markers
keywords: Helianthus; adaptation; drought; selection; soil fertility; sunflower; water limitation