Ecological constraints on the evolution of plasticity in plants. Evolutionary ecology

Abstract. Signal detection and response are fundamental to all aspects of phenotypic plasticity. This paper proposes a novel mechanism that may act as a general limit to the evolution of plasticity, based on how selection on signal detection and response is likely to interact with gene flow in a spatially autocorrelated environment. The factors promoting the evolution of plasticity are re-viewed, highlighting the crucial role of information acquisition and developmental lags, and of selection in spatially and temporally structured habitats. Classic studies of the evolution of plasticity include those on shade avoidance, on morphological plasticity in clonal plants, and on selection in spatially structured model populations. Comparative studies indicate that, among clonal plants, extensive plasticity in growth form is favored in patchy environments, as expected. However, among woody lineages from Madagascar, plasticity in photosynthetic pathway (CAM vs. C3) appears to confer competitive success in areas of intermediate drought stress, rather than allowing individually plastic species to expand their ranges, as has often been argued. The extent of phenotypic plasticity cannot only determine species distributions, it can also affect the sign and magnitude of interactions between species. There appears to be some relationship between developmental plasticity and evolutionary lability: traits that show relatively few transitions within and among plant lineage