Climate-related variability in carbon and oxygen stable isotopes among populations of Aleppo pine grown in common-garden tests

Abstract

The Aleppo pine (Pinus halepensis Mill.) is found in the Mediterranean under a broad range of moisture and thermal conditions. Differences in severity and duration of water stress among native habitats may act as selective forces shaping the populations' genetic make-up in terms of contrasting drought strategies. We hypothesised that these strategies should translate into intraspecific variation in carbon isotope composition (d 13 C, surrogate of intrinsic water-use efficiency, WUE i ) of wood holocellulose, and such variation might be linked to changes in oxygen isotope composition (d 18 O, proxy of stomatal conductance) and to some climatic features at origin. Thus, we evaluated d 13 C, d 18 O, growth and survival for 25 Aleppo pine populations covering its geographic range and grown in two common-garden tests. We found intraspecific variability for d 13 C and growth, with high-WUE i populations (which showed 18 O-enriched holocellulose) having low growth. These results suggest stomatal regulation as common control for d 13 C and productivity. We also detected sizeable relationships between d 13 C and climate factors related to the magnitude and timing of drought such as the ratio of summer to annual rainfall. The main climate variable associated with d 18 O was minimum temperature, but only in the coldest trial, suggesting differences in growth rhythms among sources. Overall, slow growing populations from highly-seasonal dry areas of the western Mediterranean exhibited a conservative water-use, as opposed to fast growing sources from the northernmost distribution range. The particular behaviour of the Mediterranean Aleppo pine as compared with other conifers demonstrates different selective roles of climate variables in determining intraspecific fitness.

Phenotypic plasticity in Pinus pinaster δ13C: environment modulates genetic variation

“…IIB), which suggests that the WUE was affected by both, external and internal factors, like water availability and gas exchange performance, or by their interaction. Higher δ 13 C variability in the drier trial site was also observed by Voltas et al (2008) in Pinus halepensis populations.…”

Ecological and association genetics in two Mediterranean pine species

“…As reviewed by Warren et al (2001) C from P. halepensis wood as a proxy for WUE estimation has been previously confirmed by (Ferrio et al 2003;Voltas et al 2008Voltas et al , 2015.…”

“…is a long-lived conifer, widely distributed across the Mediterranean Basin, where it can be found across environments encompassing a broad range of moisture and thermal conditions. It has also remarkable capacity to cope with dry and low-fertility environments (Voltas et al 2008;Santos-del-Blanco et al 2013). Previous studies suggest that Aleppo pine populations expanded westwards all around the Mediterranean basin from some refugia located in the southern part of the Balkan Peninsula (Grivet et al 2009).…”

Ecología evolutiva de la reproducción en dos pinos mediterráneos: Pinus pinaster Ait. y Pinus halepensis Mill.

“…Also, studies that integrate a comprehensive set of fitness-related traits will provide a more realistic picture of adaptive strategies (Pigliucci, 2004). An integrated analysis of further traits such as constitutive and induced defences (Sampedro et al, 2011), drought resistance (Voltas et al, 2008), cold tolerance (Climent et al, 2009), phenology (Salmela et al, 2013, serotiny (Hernández-Serrano et al in prep), stem architecture (Sierra-de-Grado et al, 1999), ontogenetic heteroblasty , bark thickness and seed size and dispersal ability (Santos-del-Blanco & Climent, 2011) will be highly valuable.…”

“…Los caracteres más comúnmente estudiados en pinos mediterráneos en ensayos de ambiente común han sido por un lado el crecimiento (ALÍA et al 1995, CHAMBEL et al 2007) y por otro, caracteres fisiológicos de valor adaptativo, como la resistencia al frío (CLIMENT et al 2009), a la sequía , VOLTAS et al 2008) o fenología (CODESIDO y FERNANDEZ-LOPEZ 2009). Desde un punto de vista evolutivo, un carácter se considera adaptativo si tiene una influencia positiva en el número de descendientes producidos por un organismo.…”