Natural selection favours drought escape and an acquisitive resource‐use strategy in semi‐arid Mediterranean shrubs

Natural selection is the major force driving adaptive evolution in natural populations, varying in strength, direction, and form through space and time, especially in highly variable environments such as Mediterranean ecosystems. Although a conservative resource-use strategy has been hypothesized to be adaptive in Mediterranean taxa, patterns of selection at the intraspecific level, i.e., the suite of traits determining individual fitness, are largely unknown.
Using a phenotypic selection experiment in natural semiarid conditions, we measured direct and indirect selection acting through two different fitness components (survival and reproduction), to assess the adaptive value of 20 ecophysiological traits on individuals of two gypsum endemic species, Centaurea hyssopifolia and Helianthemum squamatum, dwelling in environments with contrasting abiotic conditions (south- and north-facing slopes) during two climatically contrasting years (dry and mesic). This allowed quantifying the magnit..., ,