Abstract
Local competitive interactions strongly influence plant community dynamics. To maintain their performance under competition, clonal plants may plastically modify their network architecture to grow in the direction of least interference. The adaptive value of this plastic avoidance response may depend, however, on traits linked with the plant’s structural blueprint and ontogeny. We tested this hypothesis using virtual populations. We used an Individual Based Model to simulate competitive interactions among clones within a plant population. Clonal growth was studied under three competition intensities in plastic and non-plastic individuals. Plasticity buffered the negative impacts of competition at intermediate densities of competitors by promoting clone clumping. Success despite competition was promoted by traits linked with (1) the plant’s structural blueprint (weak apical dominance and sympodial growth) and (2) ontogenetic processes, with an increasing or a decreasing dependence of the elongation process on the branch generation level or length along the competition intensity gradient respectively. The adaptive value of the plastic avoidance response depended on the same traits. This response only modulated their importance for clone success. Our results show that structural blueprint and ontogeny can be primary filters of plasticity and can have strong implications for evolutionary ecology, as they may explain why clonal plants have developed many species-specific plastic avoidance behaviours.
Highlights
Local interactions such as competition are one of the principal drivers of plant community assemblages and determine plant spatial and temporal dynamics (Rees et al 1996; Gibson 1999; Warren et al 2002; Wilson 2007)
Experimental or field studies that compare plant architecture in the presence or absence of competitors report a large range of effective responses to competition or intensities in these responses (Cheplick and Gutierrez 2000; Markuvitz and Turkington 2000; Novoplansky 2009; Bittebiere et al 2012a; Oborny et al 2012). We argue that this gap between expected and observed architectures should be explained by the interaction between plasticity and two other processes defining the architecture: the structural blueprint and ontogeny (Huber et al 1999)
We aimed to determine (i) under which conditions of competition intensity plastic avoidance was adaptive and (ii) which traits linked with the structural blueprint and with ontogeny promoted the adaptive value of plasticity
Summary
Local interactions such as competition are one of the principal drivers of plant community assemblages and determine plant spatial and temporal dynamics (Rees et al 1996; Gibson 1999; Warren et al 2002; Wilson 2007). Many studies have demonstrated that plants can actively modify their architecture (Weijschedé et al 2008; Herben and Novoplansky 2010; Bittebiere et al 2012a), based on environmental signals in order to limit the effects of the presence of competitors on their performance (Sultan, 1995; Novoplansky 2009). The nature of these architectural modifications (e.g., internode elongation or shortening) can strongly influence the outcome of competitive interactions (Bittebiere et al 2012b). Experimental or field studies that compare plant architecture in the presence or absence of competitors report a large range of effective (i.e., observed) responses to competition (e.g., either an increase or a decrease in the inter-ramet distance or branching frequency) or intensities in these responses (from low to high variation in these traits) (Cheplick and Gutierrez 2000; Markuvitz and Turkington 2000; Novoplansky 2009; Bittebiere et al 2012a; Oborny et al 2012)
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