Morphometric variation in a rare endemic Aquilegia (Ranunculaceae) in the Carpathians

Abstract

To estimate the extent to which the allometric variability in Aquilegia nigricans ssp. subscaposa individuals is adaptive, we measured some morphometric traits of this rare endemic in a lowland grassland and oak – beech forest, and in a high plateau grassland. We expected light and elevation to be the main environmental factors responsible for the observed morphologic variation. Plant size was generally greater under shade conditions. The mean lengths of leaf petioles and basal leaflets were significantly greater, and the number of basal leaves significantly smaller in the forest understory. No morphometric traits differed significantly and solely between high and low elevation populations. Plant canopy development and fertility measures showed no clear responses to different light and altitudinal conditions. Significant differences in occurrence of the shapes of the first stem leaf were only detected between the populations in the most contrasting conditions: open montane grasslands and lowland forest understory. Aquilegias growing under forest canopy shade more frequently develop composed blades and/or lobed margins on stem leaves. Contrary to the initial hypothesis, the smallest within-population allometric variability was recorded in the most favourable habitat. The adaptive benefits that emerge from aquilegia's large morphometric variability are not enough for successful dispersion and colonization of new sites.

Key words:

• Adaptive allometric adjustments
• altitude difference
• leaf shape
• light availability
• plant size
• fertility
• within- and between-population variability

Acknowledgements

We are grateful to Dr Lee Miller, Prof Vasile Cristea and the reviewers for their valuable comments and suggestions. The fieldwork expenses were supported by a research grant (A52/2002 CNCSIS) provided by the Ministry of Education and Research (Bucharest, Romania).