2005/03/09 by PETER STOLL, Peter Stoll, ELKE BERGIUS · 6 citations
Agricultural and Biological Sciences · Environmental Science · #Plant and animal studies #Ecology and Vegetation Dynamics Studies #Plant Parasitism and Resistance
paper · doi:10.1111/j.0022-0477.2005.00989.x
Summary We used simulated and experimental plant populations to analyse mortality‐driven pattern formation under size‐dependent competition. Larger plants had an advantage under size‐asymmetric but not under symmetric competition. Initial patterns were random or clumped. The simulations were individual‐based and spatially explicit. Size‐dependent competition was modelled with different rules to partition overlapping zones of influence. The experiment used genotypes of Arabidopsis thaliana with different morphological plasticity and hence size‐dependent competition. Compared with wild types, transgenic individuals over‐expressed phytochrome A and had decreased plasticity because of disabled phytochrome‐mediated shade avoidance. Therefore, competition among transgenics was more asymmetric compared with wild‐types. Density‐dependent mortality under symmetric competition did not substantially change the initial spatial pattern. Conversely, simulations under asymmetric competition and experimental patterns of transgenic over‐expressors showed patterns of survivors that deviated substantially from random mortality independent of initial patterns. Small‐scale initial patterns of wild types were regular rather than random or clumped. We hypothesize that this small‐scale regularity may be explained by early shade avoidance of seedlings in their cotyledon stage. Our experimental results support predictions from an individual‐based simulation model and support the conclusion that regular spatial patterns of surviving individuals should be interpreted as evidence for strong, asymmetric competitive interactions and subsequent density‐dependent mortality.