Fluctuating asymmetry indicates levels of competition in an even-aged poplar clone

Fluctuating asymmetries are small random deviations from perfect bilateral symmetry that result from imperfect regulation of development. Recently, fluctuating asymmetry has been suggested as a tool for monitoring levels of ecological stress within and between populations. Unfortunately, such comparisons of fluctuating asymmetry may be confounded by genetic or age differences among environments. In this study we use a genetically controlled field experiment to determine differences in fluctuating asymmetry due solely to different competitive regimes. We determined fluctuating asymmetry in poplar leaf shape for leaves taken from an even-aged clone grown in six different competitive regimes. We show that increases in intra- and interspecific competition increase fluctuating asymmetry in the leaves of this clone. This supports the use of fluctuating asymmetry as a tool for detecting common environmental stresses such as competition.