Population divergence in the plasticity of the response of Quercus coccifera to the light environment

Abstract

Summary Quercus coccifera, a slow‐growing, evergreen oak, grows in contrasting environments in the Mediterranean Basin. Habitat‐based selection may have promoted divergence between populations with respect to phenotypic plasticity and genetic variability. We tested the hypothesis that populations of the Q. coccifera originating from a rock outcrop, a continental garrigue formation and an oceanic forest would differ in their plastic response to light intensity. Plants from these populations were grown from acorns in a common garden at 100% and 20% full sunlight. Light response analysis was based on photochemical efficiency, xanthophyll pool, nutrient allocation, growth, crown architecture and light absorption. Light‐responsive characters ranged from the subcellular to the whole‐plant level. The greatest divergences between sun and shade phenotypes were observed in leaf size, leaf angle and leaf area ratio. However, plasticity in these traits depended on plant provenance. Regardless of the level of organization, populations were invariably ranked in the same order of plasticity when averaged over light‐responsive features, with plants originating from the rock outcrop showing the least plasticity and those from the forest the largest. The forest population also had the greatest genetic variability with respect to the isoperoxidase polymorphism. Among populations, plants originating from the phosphorus‐deficient rock outcrop contained 30% more P per unit dry weight. Plants from the forest population had 5% more photoprotective xanthophylls, 30% larger total leaf area, with less lobed and larger leaves and a differential plasticity in leaf azimuth. Differences among populations suggested ecotypic differentiation towards less phenotypic plasticity in the most homogeneous light environments. The ecological breadth of the species seemed to be derived not only from its tolerance of Mediterranean conditions but also from the specialization of its populations in contrasting habitats.

Light acclimation of leaf gas exchange in two Tunisian cork oak populations from contrasting environmental conditions

“…The results found in this study show that the ecological origin of the populations determined their capacity for light acclimation. Blaguer et al (2001) also found that populations of Q. coccifera, an evergreen oak originating from different localities in the Mediterranean, differ in their plastic response to light intensity. They concluded that differences among populations suggested an ecotypic differentiation towards less phenotypic plasticity in the most homogeneous light environments (Blaguer et al 2001).…”

“…Blaguer et al (2001) also found that populations of Q. coccifera, an evergreen oak originating from different localities in the Mediterranean, differ in their plastic response to light intensity. They concluded that differences among populations suggested an ecotypic differentiation towards less phenotypic plasticity in the most homogeneous light environments (Blaguer et al 2001). More recently, Aranda et al (2005) found differences in cold tolerance among populations of cork oak.…”

“…Our findings indicate a divergence in the plasticity of Q. suber populations in response to the light environment. In this species, a change in plasticity may be a consequence of habitat-based selection, as proposed by Blaguer et al (2001).…”

“…Long-term selection can lead to the development of morphological and physiological adaptations to the local environment, giving rise to ecotypic differentiation (Blaguer et al 2001, Magri et al 2006, 2007. Plant species can cope with this environmental variability by enhancing phenotypic plasticity and adapting to local climates (Sultan 2003).…”

Adjustment of photosynthetic carbon assimilation to higher growth irradiance in three-year-old seedlings of two Tunisian provenances of Cork Oak (Quercus suber L.)

“…Different studies showed a possible intraspecific variability and phenotypic plasticity in Cork oak as an adaptation to contrasting regional climate conditions (Balaguer et al 2001, Aranda et al 2005, Staudt et al 2008, Ramirez-Valiente et al 2010, Matesanz & Valladares 2014, Gratani 2014. Investigating the influence of full-sun on seedling hardiness, Calzavara et al (2015) suggested that the acclimation process can induce changes in physiological, anatomical, and morphological traits of plants, favoring their establishment after transplantation to the field.…”