Intraspecific variation of leaf pubescence and drought response in Encelia farinosa associated with contrasting desert environments

Abstract

SUMMARYTraits associated with leaf energy balance are especially important for desert plants because decoupling leaf and ambient temperatures can be critical for maximizing productivity and survival in these hot, dry regions. Deserts are also one of the most climatically unpredictable and heterogeneous biomes; thus, variation of energy balance characters due either to plasticity or genetic differentiation might also be crucial to the success of desert plant species. In a common garden environment we examined variation in the traits associated with energy balance and productivity in Encelia farinosa A. Gray (brittlebush) plants. Comparing two populations from contrasting rainfall and drought climates, we found that plants from the wetter site (Superior, Arizona) always maintained higher leaf absorptances than plants from the more xeric region (Oatman, Arizona) when at similar water potentials. Superior plants also increased stomatal conductance and photosynthesis in response to mid-spring rainfall, whereas Oatman plants did not. Oatman plants, however, tended to have greater leaf areas and continuous spring growth, which made them larger than Superior plants, yet both populations produced the same number of flower heads. The differences for these traits, and the associations among them, agree with predictions based on the contrasting drought and rainfall environments of these two populations. Our results suggest that the differences might represent alternative suites of characters of selective importance for maximizing carbon gain over the climatically variable range of this widespread species. Furthermore, these differences, detected in common environment conditions, might have a genetic basis, which might contribute to a greater potential for local adaptation in this species.

The Evolution of Plant Functional Variation: Traits, Spectra, and Strategies

“…Across broad environmental gradients, increasing numbers of broad interspecific Fonseca et al 2000;Shipley and Lechowicz 2000;Wright et al 2001;Ackerly 2003) and narrow intragenus or intraspecific studies (Sandquist and Ehleringer 1997;Oleksyn et al 1998Oleksyn et al , 2003Ackerly and Donoghue 1998;Cavender-Bares and Holbrook 2001;Miller et al 2001) have shown strong evidence for a genetic basis for variation among populations or species that is at the very least consistent with general hypotheses about the adaptive value of the trait(s) in question and/or the trade-offs between traits (and hence the selection process). However, most of these studies lack any other genetic information and do not directly assess whether the trait or traits in question actually enhance any fitness component.…”

Leaf anatomy of Qualea parviflora (Vochysiaceae) in three phytophysiognomies of the Mato Grosso State, Brazil

“…It corroborates Lin and Ehleringer (1983), who stated that the non-glandular trichomes work in light reflection. Additionally, Sandquist and Ehleringer (1997) state that the non-glandular trichomes reduce the transpiration rate, either by the increase in solar radiation reflection, which reduces the temperature, or by the thickness of the air layer trapped above the leaf, which works as barrier to water loss. Manetas (2003) also proved that the trichomes might protect the tissues against damages caused by UV-B rays.…”

Pérdida de pubescencia foliar y sus efectos fisiológicos en Espeletia paipana (Asterales, Asteraceae), en el departamento de Boyacá-Colombia

“…En hojas sanas, la pubescencia abundante aumenta la capa límite, reduciendo el choque térmico con el ambiente y permitiendo la apertura estomática y la difusión de gases durante el día (Meinzer & Golstein, 1985;Gates, 1980). Se ha visto que con el incremento de la altitud, la pubescencia foliar sirve para asegurar el desacople térmico de la temperatura ambiente y reflejar un mayor porcentaje de radiación, así esto implique una menor fijación de carbono (Sandquist & Ehleringer, 1997).…”