Evolution of bow-tie architectures in biology Friedlander, Tamar Mayo, Avraham Tlusty, Tsvi Alon, Uri ddc:576 Bow-tie or hourglass structure is a common architectural feature found in many biological systems. A bow-tie in a multi-layered structure occurs when intermediate layers have much fewer components than the input and output layers. Examples include metabolism where a handful of building blocks mediate between multiple input nutrients and multiple output biomass components, and signaling networks where information from numerous receptor types passes through a small set of signaling pathways to regulate multiple output genes. Little is known, however, about how bow-tie architectures evolve. Here, we address the evolution of bow-tie architectures using simulations of multi-layered systems evolving to fulfill a given input-output goal. We find that bow-ties spontaneously evolve when the information in the evolutionary goal can be compressed. Mathematically speaking, bow-ties evolve when the rank of the input-output matrix describing the evolutionary goal is deficient. The maximal compression possible (the rank of the goal) determines the size of the narrowest part of the network—that is the bow-tie. A further requirement is that a process is active to reduce the number of links in the network, such as product-rule mutations, otherwise a non-bow-tie solution is found in the evolutionary simulations. This offers a mechanism to understand a common architectural principle of biological systems, and a way to quantitate the effective rank of the goals under which they evolved. Public Library of Science 2015 info:eu-repo/semantics/article doc-type:Article Article http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/1827 https://research-explorer.ista.ac.at/download/1827/5161 Friedlander T, Mayo A, Tlusty T, Alon U. Evolution of bow-tie architectures in biology. <i>PLoS Computational Biology</i>. 2015;11(3). doi:<a href="https://doi.org/10.1371/journal.pcbi.1004055">10.1371/journal.pcbi.1004055</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1371/journal.pcbi.1004055 info:eu-repo/semantics/altIdentifier/wos/000352195700006 https://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess