Tolerance assessment of Cistus ladanifer to serpentine soils by developmental stability analysis

Developmental instability is the result of random environmental perturbatio ns during development. Its absence (developmental stability) depends on an organism's ability to buffer environmental disturbances. Both genotype and environment influence the phenotypic expression of developmental instabilit y and it is susceptible to selection pressure. We studied developmental ins tability (as indicated by increased within-individual asymmetry of repeated traits) in vegetative and reproductive structures of three populations of Cistus ladanifer L. living in different soil substrates (serpentine, silice ous and contact zone) to detect tolerance to serpentine soils. Serpentine s oils, characterized by high concentrations of heavy metals (Ni, Cr, and Co) , low levels of Ca/Mg ratio and high water deficit, can adversely affect pl ant performance. In this study we demonstrated that asymmetry and within-pl ant variance were higher in the contact zone population than either the sil ica or serpentine populations, proving the adaptation of C. ladanifer to se rpentine soils. Within-population estimates of developmental instability we re concordant for both vegetative and reproductive traits. There was little or no within-individual correlation among estimates of developmental insta bility based on different structures, i.e., plants that had highly asymmetr ic leaves always had high developmental instability in translational symmet ry. Radial asymmetry of petals was negatively correlated with petal size, e specially in silica soil plants, providing evidence of selection for symmet ric and large petals. While leaf size was positively correlated with absolu te fluctuating asymmetry, suggesting selection for small or intermediate si ze leaves. Serpentine soils presented the largest foliar and floral traits, as well as shoot elongation, while silica soil plants had the smallest sco res. On the contrary, aboveground plant biomass was larger in silica soil p lants, while the contact zone plants had the lowest biomass.