CONICET | Buscador de Institutos y Recursos Humanos

Steep climatic gradients boost morphological and physiological adjustments in plants,with consequences on performance. The three principal woody species of the SierrasGrandes Mountains of central Argentina have marked differences in sapling performancealong their altitudinal distribution. We hypothesize that the steep gradient ofclimatic conditions across the species? altitudinal distribution promotes trait differencesbetween populations of different altitudes that are inherited by the followinggeneration.Seeds from different altitudes were exposed to three temperature regimes to assess differentialgermination responses. Saplings were then transplanted to a greenhouse toassess possible variations in attributes and performance after 18 months.The three species showed differences in germination responses to temperature amongaltitudes and/or in sapling attributes and performance. In Maytenus boaria and Escalloniacordobensis, germination success was higher under high temperatures for thehighest-altitude, whereas lower temperatures boosted germination of the lowest altitudes.Polylepis australis showed no differences in germination among temperaturetreatments. In the greenhouse, saplings of the three species from intermediate altitudesshowed high performance, whereas the upper and lower populations seemed to beadjusted to tolerating more stressful conditions (i.e., lower temperatures at the upperend and water stress at the lower end), showing lower performance toward both altitudinallimits.These patterns agree with those described for saplings growing under field conditions,suggesting adjustments in response to environmental changes undergone by populationsalong the altitudinal range. The marked adjustments of populations to the localenvironment suggest a potentially high impact of climatic change on species distribution.

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