Evolutionary Developmental Biology (Evo-Devo)
Hearn, David .
Coevlutionary interactions among plant anatomical characters are modular, yet selection pressure for modularity remains elusive.
Modularity is pervasive throughout biological systems ranging from molecular to ecosystem scales. Despite the ubiquity of modularity, selection pressures responsible for the evolution of modularity are still debated. A consensus, however, is that modularity can improve system robustness in the face of a changing environment either by limiting the propagation of disturbances to within a module, or by focusing system change through one or a few network hubs. Plant anatomical features provide new light on the evolution of modularity. Previous ecological-anatomical studies illustrate a tight association between climate and anatomical morphology. Using an extensive dataset consisting of over 65,000 anatomical measurements from 52 species of Adenia (Passifloraceae), in conjunction with molecular phylogenetic analysis of these species, I tested for modular structure among evolutionary changes in anatomical state. Phylogenetically-informed analyses that took phylogenetic uncertainty into account reconstructed a weighted network of evolutionary interactions among 42 morphological characters. This network was more modular than randomized networks (P<0.001), implying that evolutionary cascades of morphological change are, themselves, modular. Next, associations between climate and morphology were analyzed using modified phylogenetically independent contrasts. Although several expected correlations between climate change and morphological evolution were detected, modules in the morphological network neither limited propagation of impacts of climate change, nor were effects of climate change on anatomical state focused through network hubs. This lack of association between modular structure and climate change suggests that underlying evolutionary pressures on modular structure may have more to do with pleiotropy or developmental constraint than to impacts of external environmental change.
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1 - Towson University, 8000 York Road, Towson, MD, 21252, USA
posterior predictive p-value
Presentation Type: Oral Paper:Papers for Topics
Location: Lindell D/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 11:30 AM